Essay: Design and manufacturing of flexible fixture for different frame welding

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PROJECT REPORT

ON

‘Design and manufacturing of flexible fixture for different frame welding’

Mechanical Engineering

Submitted by

1) G Jxxxxxx
2) Z Pxxxxxxxxxxx
3) K Pxxxxx
4) R Nxxxx

1. INTRODUCTION

1.1 Jigs and fixture:-

The fixture is a special tool for holding a work piece in proper position during manufacturing operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in manufacturing process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages. To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators.

Jig: is a fixture with an additional feature of tool guidance

Fixture: fixture, being used in machine shop, are strong and rigid mechanical devices which enable easy, quick and consistently accurate locating. Supporting and clamping, blanks against cutting tools and result faster and accurate machining with consistent quality, functional ability and interchangeability.

1.2 Fixture in arc welding process:-

As the manufacturing costs of the metal-working industry are nowadays mainly determined by the costs of labor with accuracy, many industries are compelled to rationalize their manufacturing methods by partially and fully mechanized production processes. In the field of welding engineering where a consistently excellent quality with an optimum productivity is a must, automation aspects are consequently taken into account.

Fig.1.2 Manual metal arc welding process (MMAW)

Figure shows manual metal arc welding (MMAW), in this case manual electrode welding. The control of the electrode and/or the arc is carried out manually. The filler metal (the consumable electrode) is also fed manually to the welding point.
a) Role of flexible fixture in arc welding processes:-

‘ Hold the parts in correct position.’
‘ Assist and control the joining process.”
‘ Mechanically or Alignment of work pieces
o ‘
‘ Tooling for hot processes should withstand heat and accelerate or retard flow of heat’Hot fixtures should have thermal expansion coefficient so that it remains functional.

Advantages of fixture used in arc welding processes:-


‘ To assure high accuracy of welding parts.’

‘ Provide for interchangeability in assembly.

‘ Enable heavy and complex parts to be weld.’

‘ Reduce distortion.

‘ Saving in labor time and less kills require.’

‘ Use improve the safety and reduced accidents.’

‘ Produce Interchangeable and Quality parts
‘ Reduction cost of manufacturing”

1.3 Fundamental principles of Arc weld flexible Fixtures design:-

a) Locating points: Good facilities should be provided for locating the work. The article to be machined must be easily inserted and quickly taken out from the fixture so that no time is wasted in placing the work piece in position to perform operations. The position of work piece should be accurate with respect to tool guiding in the jig or setting elements in fixture.

b) fool proof: It can be defined as ‘the incorporation of design feature in the fixture that will make it possible to lead the work into fixture, in an improper position but will not interface with loading and unloading the work piece” there are many fool proofing device, such as fooling pegs, blocks or pins which clear correctly position parts but prevent incorrectly loaded parts from entering the fixture body.
c) Simplicity surface: machining on the work piece must be clearly visible to the worker. He should not be required to bend is neck for seeing the work piece or work surface.
d) Weight of weld fixtures: It should be easy to handle smaller in size and low cost in regard to amount of material used without sacrificing rigidity and stiffness.

e) Materials for jigs and fixtures: Usually made of hardened materials to avoid frequent damage and to resist wear.

Example- MS, Cast iron, Die steel, CS, HSS.

f) Clamping device: It should be as simple as possible without sacrificing effectiveness. The strength of clamp should be such that not only to hold the work piece firmly in place but also to take the Thermal stresses produced during welding, when designing the weld fixtures.

2. LITERATURE REVIEW

The fixture is a special tool for holding a work piece in proper position during Fabrication operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in Fabrication process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages.

To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators. Clamping has to be appropriately planned at the stage of machining fixture design. The design of a fixture is a highly complex and intuitive process, which require knowledge. Fabrication Fixture design plays an important role at the setup planning phase. Proper fixture design is crucial for developing product quality in different terms of accuracy, surface finish and precision of the machined parts in existing design the Fabrication fixture set up is done manually, so the aim of this project is to replace with Fabrication fixture to save time for loading and unloading of component. Fabrication fixture provides the manufacturer for flexibility in holding forces and to optimize design for Fabrication operation as well as process function ability.

2.1 Steps of Fabrication fixture design

Successful fixture designs begin with a logical and systematic plan. With a complete analysis of the

Fixture’s functional requirements, very few design problems occur. When they do, chances are some

Design requirements were forgotten or underestimated. The work piece, processing, tooling and

Available machine tools may affect the extent of planning needed. Preliminary analysis may take from

Few hours up to several days for more complicated fixture designs. Fixture design is a five-step

Problem-solving process. The following is a detailed analysis of each step.

Step 1: Define Requirements

To initiate the Fabrication fixture-design process, clearly state the problem to be solved or needs to be met. State these requirements as broadly as possible, but specifically enough to define the scope of the design project. The designer should ask some basic questions: Is the new tooling required for first-time production or to improve existing production

Step 2: Gather/Analyze Information

Collect all relevant data and assemble it for evaluation. The main sources of information are the part print process sheets. Make sure that part documents and records are current. For example, verify that the shop print is the current revision, and the processing information is up-to-date. Check with the design department for pending part revisions. An important part of the evaluation process is note taking. Complete, accurate notes allow designers to record important information. With these notes, they should be able to fill in all items on the “Checklist for Design Considerations.” All ideas, thoughts, observations, and any other data about the part or fixture are then available for later reference. It is always better to have too many ideas about a particular design than too few. Four categories of design considerations need to be taken into account at this time: work piece specifications, operation variables, availability of equipment, and personnel. These categories, while separately covered here, are actually

Step 3: Develop Several Options

This phase of the fixture-design process requires the most creativity. A typical work-piece can be located and clamped several different ways. The natural tendency is to think of one solution, then develop and refine it while blocking out other, perhaps better solutions. A designer should brainstorm for several good tooling alternatives, not just choose one path right away. During this phase, the designer’s goal should be adding options, not discarding them. In the interest of economy, alternative designs should be developed only far enough to make sure they are feasible and to do a cost estimate. The designer usually starts with at least three options: permanent, modular, and general-purpose work holding. Each of these options has many clamping and locating options of its own.

— Page 15
The more standard locating and clamping. Devices that a designer is familiar with, the more creative he can be. Devices that a designer is familiar with, the more creative he can be. Areas for locating a part include flat exterior surfaces (machined and machined), cylindrical and curved exterior surfaces. The exact procedure used to construct the preliminary design sketches is not as important as the items sketched. Generally, the preliminary sketch should start should start with the part to be fixtured. The required locating and supporting elements, including a base, should be the next items added. Then sketch the clamping devices. Finally, add the machine tool and cutting tools. Sketching these items together helps identify any problem areas in the design of the complete fixture.

Step 4: Choose the Best Option

The total cost to manufacture a part is the sum of per-piece run cost, setup cost, and tooling cost. Expressed as a These variables are described below with sample values from three tooling options: a modular fixture, a permanent fixture, and a hydraulically powered permanent fixture.

Step 5: Implement the Design

The final phase of the fixture-design process consists of turning the chosen design approach into reality. Final details are decided, final drawings are made, and the tooling is built and tested. The following guidelines should be considered during the final-design process to make the fixture less costly while improving its efficiency. These rules are a mix of practical considerations, sound design practices, and common sense

(I)Use standard components:

The economies of standard parts apply to tooling components as well as to manufactured products. Standard, readily available components include clamps, locators, supports, studs, nuts, pins and a host of other elements. Most designers would never think of having the shop make cap screws, bolts or nuts for a fixture. Likewise, no standard tooling components should be made in-house. The first rule of economic design is: Never build any component you can buy. Commercially available tooling components are manufactured in large quantities for much greater economy. In most cases, the
Cost of buying a component is less than 20% of the cost of making it.

— Page 16
(II)Use prefinished materials:

Prefinished and preformed materials should be used where possible to lower costs and simplify construction. These materials include precision-ground flat stock, drill rod, structural sections, cast tooling sections, precast tooling bodies, tooling plates, and other standard preformed materials. Including these materials in a design both reduces the design time and lowers the labor cost.

(III)Eliminate finishing operations:

Finishing operations should never be performed for cosmetic purposes. Making a Fabrication fixture look better often can double its cost. Here are a few suggestions to keep in mind with regard to finishing operations.

The most cost-effective tooling tolerance for a locator is approximately 30% to 50% of the work piece’s tolerance. Tighter tolerances normally add extra cost to the tooling with little benefit to the process. Where necessary, tighter tolerances can be used, but tighter tolerances do not necessarily result in a better fixture, only a more expensive one.

2.2 MEANING OF LOCATION

The location refers to the establishment of a desired relationship between the work piece and the jigs or fixture correctness of location directly influences the accuracy of the finished product. To position the work piece w.r.t. to tool, to ensure precision in machining. Dimensional and positional relationship between work piece and tool device to establish and maintain position of a part in a jig or fixture.
The jigs and fixtures are desired so that all undesirable movements of the work piece can be restricted. Determination of the locating points and clamping of the work piece serve to restrict movements of the component in any direction, while setting it in a particular pre-decided position relative to the jig. Before deciding the locating points it is advisable to find out the all possible degrees of freedom of the work piece. Then some of the degrees of freedom or all of them are restrained by making suitable arrangements. These arrangements are called locators. These are described in details in location principle.
— Page 17
2.2.1 Six pin (3-2-1) locating principle

A work piece free in space can move in an infinite number of directions. For analysis, this motion can be broken down into twelve directional movements, or “degrees of freedom.” All twelve degrees of freedom must be restricted to ensure proper referencing of a work piece.

Fig. 2.1. 3-2-1 locating principle
As shown in Figure 2.02, the twelve degrees of freedom all relate to the central axes of the work piece. Notice the six axial degrees of freedom and six radial degrees of freedom. The axial degrees of freedom permit straight-line movement in both directions along the three principal axes, shown as x, y, and z. The radial degrees of freedom permit rotational movement, in both clockwise and counter clockwise radial directions, around the same three axes. The devices that restrict a work piece’s movement are the locators. The locators, therefore, must be strong enough to maintain the position of the work piece and to resist the cutting forces. This fact also points out a crucial element in work holder design: locators, not clamps, must hold the work piece against the cutting forces. Locators provide a positive stop for the work piece. Placed against the stop, the work piece cannot move. Clamps, on the other hand, rely only upon friction between the clamp and the clamped surface to hold the work piece. Sufficient force could move the work piece. Clamps are only intended to hold the work piece against the locators.

6 translational degrees of freedom: +X, -X, +Y, -Y, +Z, -Z

6 rotational degrees of freedom:

— Page 18

You must fix all the 12 degrees of freedom except the three transitional degrees of freedom (-X, -Y and -Z) in order to locate the work piece in the fixture. So, 9 degrees of freedom of the work piece need to be fixed by using the 3-2-1 method.

Fig 2.2 fixture set up-(3-2-1 on principle)

— Page 19

2.3 CLAMPING

Once work piece is located, it is necessary to press it against locating surfaces and hold it there against the force acting upon it. The tool designer refers to this action as clamping and the mechanisms used for this action are known as clamps.

‘ Clamp should firmly hold the work piece without distorting it.
‘ Should overcome the maximum possible force exerted on work piece by using minimum clamping force
‘ Easy to operate
‘ Vibrations should tighten the cams and wedges in the clamp design (if any) and not loosen them

Fig 2.3 position of holding work piece

2.4Fixturing Functional Requirements

1) Stable resting,

2) Accurate localization.

3) support reinforcement,

4) stable clamping,

5) fore closure(or total restraint) and

6) Quality performance.

— Page 20

The functions have strong precede the first five functions are required at the fixturing stage, and sequentially. When a work piece is placed into a fixture, it must first assume a stable resting against the gravity. Then, the locators should provide accurate localization. Next, supports are moved in place, and finally clamps are activated for the part immobilization (force-closure). The part location must be maintained in the process of instantiating clamps without work piece lift-off. The performance of the fixture is ultimately defined as work piece geometric error during the manufacturing stage. The geometric error is mainly determined by the fixture localization accuracy and the work piece static and elastic deformation during manufacturing. There are additional constraints to be satisfied such as interference-free and easy loading and unloading.

2.4.1 Design Consideration in Fixtures

The main frame of fixture must be strong enough so that deflection of the fixture is as minimum as possible. This deflection of fixture is caused because of forces of cutting, clamping of the work piece or clamping to the machine table. The main frame of the fixture should have the mass to prevent vibration and chatter.
‘ Frames may be built from simple sections so that frames may be fastened with screws or welded whenever necessary. Those parts of the frame that remain permanently with the fixture may be welded. Those parts that need frequent changing may be held with the screws.

‘ In the situation, where the body of fixture has complex shape, it may be cast from good grade of cast iron. All locator’s clamps should be easily visible to the operator. ‘

‘ Clamping should be fast enough and require least amount of effort.’

‘ Clamps should be arranged so that they are readily available and may be easily removed.’

‘ Clamps should be supported with springs so that clamps are held against the bolt head wherever possible.’
‘ Permitted to swing as far as it is necessary for removal of the work piece.

— Page 21


PROBLEM DEFINATION:-

From literature it have been found that there is not any arc welding flexible fixtures available. It is planned to Design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

— Page 22

3. DESIGN ASPECTS

3.1 Individual Design of flexible fixture parts

This section covered different aspects of design of arc welding fixture with cutting action.

3.1.1 Design of supporting frame

Frame is consist of uniform member (of circular section, angle section, channel section, square section etc.) joined together at their ends by riveting or welding.in case of our project welding fixture, we need a support structure of all other member like square slotted pate, clamping device and work piece plate which is required to welded.so it is easy to fabricate a square section plate frame by welding. So we select the frame as a hollow square cross section plate from Indian standard.
Selection of material for frame
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993) Fe 470 W Steel with a minimum tensile strength of 470 N/mm and of guaranteed fusion welding quality in real application of fe470 in clutch and free wheel clutch.

‘ Specification of frame material i.e. Fe 470
‘ Indian standard designation = Fe 470

‘ Tensile strength ( minimum) = 580 N/mm”

‘ Yield strength (minimum) = 430 N/mm”

‘ Minimum percentage elongation = 21

‘ Bending strength = 230 N/mm”

— Page – 23

Fig 3.1 Drawing of supporting frame

Now, assume that the frame is a simply supported beam carrying Uniform Distributed Load (U.D.L) as 10,000 Newton on 1300 mm length. A little consideration show that a frame is subjected to bending as well as static load. As shown in table no.1 various value of F.O.S. for various material based on Indian standard.

Material Steady load Live load Shock load

Cast iron 5 to 6 8 to 12 16 to 20

Wrought iron 4 7 10 to 15

Steel 5 8 12 to 16

Soft material and 6 9 15
alloys

Leather 9 12 15

Timber 7 10 to 15 20

Table no. 1 various value of F.O.S. for various material

— Page 24

1) Frame subjecting to Static Load

Now assume factor of safety (F.O.S) = 5 (select from table no.1 for steel) Static Load (W) = 8000 N (Design load for fixture)

Design stress (”) = Yield strength / F.O.S

= 430/5

= 86 N/mm”

As per market evaluation we found standard cross section (50*50) for hollow square pipe.it capable for fixture as per loading condition.

So Area of cross section (A) = Hollow Square pipe

= 50*50

= 5 mm thick platen

Let we know that static stress

” = W/A

86 = 8000 /A
A = 8000/86

= 93.02 mm”

But, A= B”= 93.02

B = 9.64 mm > 50 mm hence safe in static loading.

2) Frame subjecting to bending Load

We know that the bending equation is given by

M/I = ”/Y = E/R

Where M = Bending moment acting at the given section

” = Bending stress

I = Moment of inertia of cross section about the neutral axis

Y = Distance from the neutral axis

— Page – 25

E = Young Modulus of elasticity of material

R = Radius of curvature of the beam

From above equation

Bending ” = M/I *Y

=M/Z

Where Z = section modulus = I / Y

Now assume that frame is a simply supported beam and also we know that Bending Moment of simply supported beam with U.D.L.

M = WL” / 8 (Equation for simply supported beam with U.D.L.)

Where W = U.D.L. on frame = 8,000N

L = Length of span (Frame) = 1300 mm

Hence M = 8,000*(1300)” ” 8

= 1690000000N*m

Now section modulus of square cross section

Z= (B4 – H4) ” 6B

= (504 – 404) ” 6*50

= 12300 mm”

Also bending ” = M”Z

= 1690000000 ” 12300

= 137.75 N/mm”

So bending stress ” = 137.75 N/mm” > 245 N/mm” (design bending stress) Hence it is prove that frame is safe in bending.

Final dimension of supporting frame

— Page – 26
Hollow square pipe cross section= 50*50 and 5mm thickness

Length of frame (L) = 1300 mm

Width of frame (W) = 400 mm

3.1.2 Design of vertical column

A machine part subjected to an axial compressive force is called strut. A strut may be horizontal, inclined, or even vertical. But a Vertical strut is known as a column. It has been observed that when a column is subjected to a compressive load and is gradually increased, a stage will reach when the column will be subjected to ultimate load. Beyond this, the column will fail by crushing and the load will be known as crushing load.

It has also been experienced, that sometimes, a compression member does not fail entirely by crushing, but also by bending i.e. buckling. If the load is gradually increased, the column will reach a stage, when it will start buckling. The load at which the column tends to buckle is called buckling load, critical load or crippling load and the column is said to have developed an elastic instability.

‘ Selection of material for vertical column
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993)We select the steel material Fe 330 as used for locomotive carriages and car structures, screw stock and other general engineering purpose.

Specification of vertical column material i.e. Fe 330
‘ Indian standard designation = Fe 330
‘ Tensile strength (minimum) = 330 N/mm”

‘ Yield strength (minimum) = 200 N/mm”

‘ Minimum percentage elongation = 26

‘ Crushing stress =330 N/mm”

‘ Young’s modulus = 0.21 * 106 N/mm”

‘ Area of cross section = 70*70 and 500 mm length

— Page – 27

Fig.3.2 drawing of vertical column

In actual practice, there are number of end condition for column. But in case our project parts as vertical column is a both ends fixed type square column.

‘ Maximum Crippling load capacity of column

Now we calculate maximum crippling load or buckling load by Rankine’s formula for column

Wc r= (”c * A) ” {1 + a (L/K)}

Where, Wcr= Crippling load

”c= Crushing stress

A = Cross sectional area of column

= 70 * 70

= 4900 mm”

a = Rankine’s constant = ”c/ (”*E)

= 1” 4500 (for mild steel)

L= Equivalent length of the column

— Page – 28
= l/2 (both ends fixed)

= 500/2

= 250

K=Least radius of gyration

=0.289 B (for square cross section) = 0.289 * 70 =20.23

Now,

Wcr= (330* 4900) ” {1 + (1” 4500 ) (250/20.23) }

= 1495215.823 N

= 1495.21 KN

So Maximum Crippling load capacity of column = 1495.21 KN

3.1.3Design of slotted plate

‘ Selection of slotted plate material

As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993). We select the steel material Fe 410 as used for specially used for High-strength Steel Plate.
‘ Specification of slotted plate material i.e. Fe 410

‘ Indian standard designation = Fe 410

‘ Tensile strength ( minimum) = 360 N/mm”

‘ Yield strength (minimum) = 225 N/mm”

‘ Minimum percentage elongation = 27

Area of cross section = 20*20 with 10 mm slot throughout length i.e. 750 mm and another plate is 1250 mm length

— Page – 29

Fig.3.3 drawing of slotted plate 1250 mm length

Fig.3.4 drawing of slotted plate 750 mm length

Now a slotted plate is design on its static strength so we assume that Factor of Safety (F.O.S) = 5 (select from table no.1 for steel)

”t = Tensile strength / F.O.S

= 360 / 5

= 72 N/mm2

— Page – 30
Also we know that ”t= W / A

72 = 8,000 / A
A = 8,000/ 72

= 111.11mm” But, A = B”

235.29= B”

B= 10.54 ~ 12 mm

Hence it is prove that frame is safe in static loading.

3.1.4 Design of shaft

A shaft is a rotating machine element which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and the resultant torque (or twisting moment) set up within the shaft permits the power to be transferred to various machines linked up to the shaft.

‘ Selection of shaft material

The material used for ordinary shaft is carbon steel of grades 40 C 8, 45 C 8, 50 C 4, 50 C 12. When a shaft of high strength is required, then an alloy steel such as nickel, nickel-chromium or chrome-vanadium steel is used. But as per our requirement is medium strength is needed, so we select ordinary steel of grade 50 C 4.

‘ Specification of shaft material i.e. 50 C 4.

‘ Indian standard designation = 50 C 4

‘ Ultimate tensile strength = 1080 N/mm”

‘ Yield strength =930 N/mm”

‘ Permissible tensile stress = 0.6”u

= 0.6 * 1080

— Page – 31

= 648 N/mm2

Permissible shear stress = 0.18”u

=0.18* 1080

= 194.4 N/mm2

As per market evaluation we found standard diameter (30 mm) for shaft. It capable for supporting frame as per loading condition.

Cross section of shaft = 30 mm diameter

= 100 mm length

A little consideration we show that in our project shaft is subjecting only twisting moment hence we design the shaft on the pure twisting moment equation.

Fig. 3.5 drawing of shaft

Maximum torque capacity of shaft

T = ” / 16 *”*d3

=” / 16*194.4*(30)3

= 1030599.47Nm

=1030.59 KNm

Hence Maximum torque capacity of shaft = 1030.59 KNm

— Page – 32

3.1.5 Design of Circular Indexing plate and Indexing pin

Main objective of indexing plate in flexible fixture is to rotate the frame at various angle i.e. Up to 180 degree of rotation and also fixed at a desired angle as per requirement of welder. A handle is provided on circular indexing plate it provide rotating movement of frame. By using an indexing pin (circular pin) frame can be fixed at required position. A hole provided on circumference of circular plate at regular interval i.e. (180/7) approximate 25 degree of each hole.by means of indexing pin attached in a Hole frame can be fixed as per requirement.

Fig. 3.6 drawing of circular indexing plate

— Page – 33

Fig.3.7 drawing of indexing pin

3.1.6 Design of clamping device and pin locator

‘ Make or buy decision for clamping device and pin locator

In case in fixture it’s required to fixed the work piece on the frame of fixture. This objective is done by using clamps and locating pin. In flexible fixture work piece i.e. plate are fixed by four clamping device and pin locator. But problems is that if clamps are make or buy from market.

If we make i.e. produced clamp in work shop so it is costly because we not produced in mass production. As well as it’s difficult to give accurate size of clamps. Also full facility of machining, casting and super finishing is not available in our work shop. As discussed above difficulty in making clamp and locating pin we purchase the required clamps and locating pin from market.

Fig.3.8 drawing of pin locator

— Page – 34

Fig.3.9 drawing of clamping device

— Page – 35

3.1.7 Summary of part design

As discussed above various parts of arc welding fixture as summarized in table no.2.

Sr. No. Name of Dimension No. of parts Material
part
1 Supporting L=1300 mm 1 Fe 470
frame W=400 mm
2 Vertical L = 500 mm 2 Fe 330
column 50*50square
cross section
3 Slotted plate 1 L= 1250 mm 2 Fe 410
4 Slotted plate 2 L= 750 mm 3 Fe 410
5 Shaft L= 100 mm 2 50 C4
D = 15 mm
6 Indexing plate D = 400 mm 1 Fe 290
t = 10 mm
with 7 hole
7 Clamp – 4 –
8 Locating pin – 4 –
Table no. 2 summary of parts for arc welding fixture

— Page – 36
3.2 Assembly of welding flexible fixture.

After all discussed above parts assemble and fabricate arc welding flexible fixture as shown fig. no 3.10

Fig.3.10 2D drawing of welding flexible fixture assembly

— Page – 37

Fig.3.11 3D drawing of welding flexible fixture assembly

— Page – 38

4. RESULTS AND CONCLUSION

Manufacture accurately interchangeable parts. Fixtures are specially designed so that large numbers of components can assembled identically, and to ensure interchangeability of components.

Facilitate economical production of engineering components.

The main functions of a welding fixture are:

Griping
A work piece in the predetermined manner of firmness and location.

Holding

Components rigid and prevent movement during welding in order to impart greater productivity and part accuracy.

Supporting and locating
Every component (part) to ensure that teach is welded within the specified limits.

Positioning

Components accurately and maintain relationship and alignment between the holder and the work piece correctly to perform on the work piece a welding operation.

Results:-

‘ welding with the help of arc welding fixtures reduced time for production of the component and also reduce the fatigue effect on worker due to ergonomically convenient for the operation

‘ with help of fixture effective clamping is done more accurate than the conventional method.

‘ the circular indexing plate gives rotational movement for the front side, topside weld more easier than the conventional method in which worker have to move the work piece as per the weld position.

— Page 39

‘ the hand cutter provide the facility to cut the frame or bar while the work piece clamped on the fixture

‘ in conventional method first worker to arrange accurately before weld of frame while in fixture with help of locator work piece automatically locating

‘ this fixtures increases the productivity, accuracy, reliability

Futures scope:-

In the above arc welding flexible fixtures various futures scope are as under

‘ Provide power driven or automatic movement of the circular indexing plate which reduces the worker fatigue.
‘ Here we only indexing up to the180 degree while with help of other clamping arrangement 360 degree indexing possible.
‘ The clamping surface are of the flat which only locate the flat work piece for provide V-shape at the end also possible for the circular work piece.
‘ To provide the scale on the slotted plate we adjust the clamp as per work piece size

— Page 40

5. REFERENCES:

Research paper:

‘ Design of Fixtures: A Review By Nisarg Parmar IJARIIE-ISSN(O)-2395-4396
http://www.ijariie.com
‘ A Review on Design of Fixtures by Shailesh S.Pachbhai & Laukik P.Raut International Journal of Engineering Research and General Science Volume 2, Issue 2, Feb-Mar 2014 ISSN 2091-2730
‘ Design of Welding Fixtures and Positiners
Prof. S.N.Shinde, Siddharth Kshirsagar, Aniruddha Patil, Tejas Parge, Ritesh Lomte
International Journal of Engineering Research and General Science Volume 2, Issue 5, August-September, 2014 ISSN 2091-2730

Books:

1) Text book of Machine Design by r.s khurmi and j.k gupta s chand publication

2) Text book of Production technology by r.k.jain Khanna publication

3) Production technology by p.c sharma s chand publication

4) Machine Tool Design by N. K. Mehta

— Page 41

A
PROJECT REPORT

ON

‘Design and manufacturing of flexible fixture for different frame welding’

Submitted by
1) Gurjar Jignesh (130210119047)
2) Zala Pushparajsinh (130210119125)
3) Katariya Piyush (140213119014)
4) Radhanpura Nadim (140213119021)

In fulfilment for the award of the degree

Of

BACHELOR OF ENGINEERING

In
Mechanical engineering

Government Engineering Collage, Bhavnagar
Gujarat Technology University, Ahmedabad

— Page 1

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Gurjar Jigneshkumar Maganbhai under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Radhanpura Nadim under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Zala Pushparajsinh, under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Katariya Piyush, under my guidance in fulfilment
Of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

ABSTRACT

In modern industrial work number of various material in different shape and size are required to develop various component for different application. Welding is one of the important fabrication process in product development work. Development of flexible fixtures for welding process is today’s requirement is reduce operation time, increase production and high quality of production.

It is planned to design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

Key words: – Welding, Flexible Fixture.

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ACKNOWLEDGEMENT

I am using this opportunity to express my gratitude to everyone who supported me throughout the course of this final year project. I am thankful for their aspiring guidance, invaluably constructive criticism and friendly advice during the project work. I am sincerely grateful to them for sharing their truthful and illuminating views on a number of issues related to the project.

I express my warm thanks to Prof. N.K Tank for their support and excellent guidance from starting to the end of our final year project at Government Engineering Collage, Bhavnagar. Also thankful to the Mechanical Department for their active cooperation and support whose encouragement, continuous guidance, helpful nature, new suggestion and ideas were invaluable for accomplishment of this work.

Thank you

Gurjar Jignesh

Zala Pushparajsinh

Katariya Piyush

Radhanpura Nadim

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LIST OF TABLES

Table No. Table Description Page No.
Table no.1 various value of F.O.S. for various material 24
Table no.2 Summary of part design 36

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LIST OF FIGURES

Figure No. Figure Description Page No.
Fig 1.1 (a) Jig (B) Fixture 10
Fig 1.2 Manual metal arc welding process 11
Fig 2.1 Principle of fixture (3-2-1) 18
Fig 2.2 Fixture set up-(3-2-1 on principle) 19
Fig 2.3 Holding work piece position 20
Fig 3.1 Drawing of supporting frame 24
Fig 3.2 Drawing of vertical column 28
Fig 3.3 Drawing of slotted plate 1250 mm 30
Fig 3.4 Drawing of slotted plate 750 mm 32
Fig 3.5 Drawing of shaft 33
Fig 3.6 Drawing of circular indexing plate 34
Fig 3.7 Drawing of indexing pin 35

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Figure No. Figure Description Page No.
Fig 3.8 Drawing of Pin locator 35
Fig 3.9 Drawing of Clamping device 35
Fig 3.10 2D drawing of welding flexible fixture assembly 37
Fig 3.11 3D drawing of welding flexible fixture assembly 38

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TABLE OF CONTENTS

Sr.no TITLE PAGE NO.
1 Abstract 3
2 Acknowledgement 4
3 List of Tables 5
4 List of Figures 6
INTRODUCTION 10
1.1 Jig and fixture
1.2 Fixture for arc welding process
a) Role of fixture in arc welding process
b) Advantages of fixture used in arc welding process
1.3 Fundamental principles of Arc weld Fixtures design
LITERATURE REVIEW 14
2.1 Steps of Fabrication fixture design
2.2 Location- Six pin (3-2-1) locating principle
2.3 Clamping
2.4 Fixturing Functional Requirements

— R Page 8
Sr.no DESIGN ASPECTS 23

3.1 Individual design of arc welding fixture
3.1.1 Design of supporting frame
3.1.2 Design of vertical column
3.1.3 Design of slotted plate
3.1.4 Design of shaft
3.1.5 Design of circular indexing plate and pin
3.1.6 Design of clamping device
3.1.7 Summary of part design
3.2 drawing and 3-D model of assembly

4. RESULTS & CONCLUSION 39

5. REFERENCES 41

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1. INTRODUCTION

1.1 Jigs and fixture:-

The fixture is a special tool for holding a work piece in proper position during manufacturing operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in manufacturing process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages. To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators.

Jig: is a fixture with an additional feature of tool guidance

Fixture: fixture, being used in machine shop, are strong and rigid mechanical devices which enable easy, quick and consistently accurate locating. Supporting and clamping, blanks against cutting tools and result faster and accurate machining with consistent quality, functional ability and interchangeability.

(A) Jig (B) Fixture

Fig. 1.1

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1.2 Fixture in arc welding process:-

As the manufacturing costs of the metal-working industry are nowadays mainly determined by the costs of labor with accuracy, many industries are compelled to rationalize their manufacturing methods by partially and fully mechanized production processes. In the field of welding engineering where a consistently excellent quality with an optimum productivity is a must, automation aspects are consequently taken into account.

Fig.1.2 Manual metal arc welding process (MMAW)

Figure shows manual metal arc welding (MMAW), in this case manual electrode welding. The control of the electrode and/or the arc is carried out manually. The filler metal (the consumable electrode) is also fed manually to the welding point.
a) Role of flexible fixture in arc welding processes:-

‘ Hold the parts in correct position.’
‘ Assist and control the joining process.”
‘ Mechanically or Alignment of work pieces
o ‘
‘ Tooling for hot processes should withstand heat and accelerate or retard flow of heat’Hot fixtures should have thermal expansion coefficient so that it remains functional.

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Advantages of fixture used in arc welding processes:-


‘ To assure high accuracy of welding parts.’

‘ Provide for interchangeability in assembly.

‘ Enable heavy and complex parts to be weld.’

‘ Reduce distortion.

‘ Saving in labor time and less kills require.’

‘ Use improve the safety and reduced accidents.’

‘ Produce Interchangeable and Quality parts
‘ Reduction cost of manufacturing”

1.3 Fundamental principles of Arc weld flexible Fixtures design:-

a) Locating points: Good facilities should be provided for locating the work. The article to be machined must be easily inserted and quickly taken out from the fixture so that no time is wasted in placing the work piece in position to perform operations. The position of work piece should be accurate with respect to tool guiding in the jig or setting elements in fixture.

b) fool proof: It can be defined as ‘the incorporation of design feature in the fixture that will make it possible to lead the work into fixture, in an improper position but will not interface with loading and unloading the work piece” there are many fool proofing device, such as fooling pegs, blocks or pins which clear correctly position parts but prevent incorrectly loaded parts from entering the fixture body.
c) Simplicity surface: machining on the work piece must be clearly visible to the worker. He should not be required to bend is neck for seeing the work piece or work surface.
d) Weight of weld fixtures: It should be easy to handle smaller in size and low cost in regard to amount of material used without sacrificing rigidity and stiffness.

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e) Materials for jigs and fixtures: Usually made of hardened materials to avoid frequent damage and to resist wear.

Example- MS, Cast iron, Die steel, CS, HSS.

f) Clamping device: It should be as simple as possible without sacrificing effectiveness. The strength of clamp should be such that not only to hold the work piece firmly in place but also to take the Thermal stresses produced during welding, when designing the weld fixtures.

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2. LITERATURE REVIEW

The fixture is a special tool for holding a work piece in proper position during Fabrication operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in Fabrication process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages.

To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators. Clamping has to be appropriately planned at the stage of machining fixture design. The design of a fixture is a highly complex and intuitive process, which require knowledge. Fabrication Fixture design plays an important role at the setup planning phase. Proper fixture design is crucial for developing product quality in different terms of accuracy, surface finish and precision of the machined parts in existing design the Fabrication fixture set up is done manually, so the aim of this project is to replace with Fabrication fixture to save time for loading and unloading of component. Fabrication fixture provides the manufacturer for flexibility in holding forces and to optimize design for Fabrication operation as well as process function ability.

2.1 Steps of Fabrication fixture design

Successful fixture designs begin with a logical and systematic plan. With a complete analysis of the

Fixture’s functional requirements, very few design problems occur. When they do, chances are some

Design requirements were forgotten or underestimated. The work piece, processing, tooling and

Available machine tools may affect the extent of planning needed. Preliminary analysis may take from

Few hours up to several days for more complicated fixture designs. Fixture design is a five-step

Problem-solving process. The following is a detailed analysis of each step.

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Step 1: Define Requirements

To initiate the Fabrication fixture-design process, clearly state the problem to be solved or needs to be met. State these requirements as broadly as possible, but specifically enough to define the scope of the design project. The designer should ask some basic questions: Is the new tooling required for first-time production or to improve existing production

Step 2: Gather/Analyze Information

Collect all relevant data and assemble it for evaluation. The main sources of information are the part print process sheets. Make sure that part documents and records are current. For example, verify that the shop print is the current revision, and the processing information is up-to-date. Check with the design department for pending part revisions. An important part of the evaluation process is note taking. Complete, accurate notes allow designers to record important information. With these notes, they should be able to fill in all items on the “Checklist for Design Considerations.” All ideas, thoughts, observations, and any other data about the part or fixture are then available for later reference. It is always better to have too many ideas about a particular design than too few. Four categories of design considerations need to be taken into account at this time: work piece specifications, operation variables, availability of equipment, and personnel. These categories, while separately covered here, are actually

Step 3: Develop Several Options

This phase of the fixture-design process requires the most creativity. A typical work-piece can be located and clamped several different ways. The natural tendency is to think of one solution, then develop and refine it while blocking out other, perhaps better solutions. A designer should brainstorm for several good tooling alternatives, not just choose one path right away. During this phase, the designer’s goal should be adding options, not discarding them. In the interest of economy, alternative designs should be developed only far enough to make sure they are feasible and to do a cost estimate. The designer usually starts with at least three options: permanent, modular, and general-purpose work holding. Each of these options has many clamping and locating options of its own.

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The more standard locating and clamping. Devices that a designer is familiar with, the more creative he can be. Devices that a designer is familiar with, the more creative he can be. Areas for locating a part include flat exterior surfaces (machined and machined), cylindrical and curved exterior surfaces. The exact procedure used to construct the preliminary design sketches is not as important as the items sketched. Generally, the preliminary sketch should start should start with the part to be fixtured. The required locating and supporting elements, including a base, should be the next items added. Then sketch the clamping devices. Finally, add the machine tool and cutting tools. Sketching these items together helps identify any problem areas in the design of the complete fixture.

Step 4: Choose the Best Option

The total cost to manufacture a part is the sum of per-piece run cost, setup cost, and tooling cost. Expressed as a These variables are described below with sample values from three tooling options: a modular fixture, a permanent fixture, and a hydraulically powered permanent fixture.

Step 5: Implement the Design

The final phase of the fixture-design process consists of turning the chosen design approach into reality. Final details are decided, final drawings are made, and the tooling is built and tested. The following guidelines should be considered during the final-design process to make the fixture less costly while improving its efficiency. These rules are a mix of practical considerations, sound design practices, and common sense

(I)Use standard components:

The economies of standard parts apply to tooling components as well as to manufactured products. Standard, readily available components include clamps, locators, supports, studs, nuts, pins and a host of other elements. Most designers would never think of having the shop make cap screws, bolts or nuts for a fixture. Likewise, no standard tooling components should be made in-house. The first rule of economic design is: Never build any component you can buy. Commercially available tooling components are manufactured in large quantities for much greater economy. In most cases, the
Cost of buying a component is less than 20% of the cost of making it.

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(II)Use prefinished materials:

Prefinished and preformed materials should be used where possible to lower costs and simplify construction. These materials include precision-ground flat stock, drill rod, structural sections, cast tooling sections, precast tooling bodies, tooling plates, and other standard preformed materials. Including these materials in a design both reduces the design time and lowers the labor cost.

(III)Eliminate finishing operations:

Finishing operations should never be performed for cosmetic purposes. Making a Fabrication fixture look better often can double its cost. Here are a few suggestions to keep in mind with regard to finishing operations.

The most cost-effective tooling tolerance for a locator is approximately 30% to 50% of the work piece’s tolerance. Tighter tolerances normally add extra cost to the tooling with little benefit to the process. Where necessary, tighter tolerances can be used, but tighter tolerances do not necessarily result in a better fixture, only a more expensive one.

2.2 MEANING OF LOCATION

The location refers to the establishment of a desired relationship between the work piece and the jigs or fixture correctness of location directly influences the accuracy of the finished product. To position the work piece w.r.t. to tool, to ensure precision in machining. Dimensional and positional relationship between work piece and tool device to establish and maintain position of a part in a jig or fixture.
The jigs and fixtures are desired so that all undesirable movements of the work piece can be restricted. Determination of the locating points and clamping of the work piece serve to restrict movements of the component in any direction, while setting it in a particular pre-decided position relative to the jig. Before deciding the locating points it is advisable to find out the all possible degrees of freedom of the work piece. Then some of the degrees of freedom or all of them are restrained by making suitable arrangements. These arrangements are called locators. These are described in details in location principle.
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2.2.1 Six pin (3-2-1) locating principle

A work piece free in space can move in an infinite number of directions. For analysis, this motion can be broken down into twelve directional movements, or “degrees of freedom.” All twelve degrees of freedom must be restricted to ensure proper referencing of a work piece.

Fig. 2.1. 3-2-1 locating principle
As shown in Figure 2.02, the twelve degrees of freedom all relate to the central axes of the work piece. Notice the six axial degrees of freedom and six radial degrees of freedom. The axial degrees of freedom permit straight-line movement in both directions along the three principal axes, shown as x, y, and z. The radial degrees of freedom permit rotational movement, in both clockwise and counter clockwise radial directions, around the same three axes. The devices that restrict a work piece’s movement are the locators. The locators, therefore, must be strong enough to maintain the position of the work piece and to resist the cutting forces. This fact also points out a crucial element in work holder design: locators, not clamps, must hold the work piece against the cutting forces. Locators provide a positive stop for the work piece. Placed against the stop, the work piece cannot move. Clamps, on the other hand, rely only upon friction between the clamp and the clamped surface to hold the work piece. Sufficient force could move the work piece. Clamps are only intended to hold the work piece against the locators.

6 translational degrees of freedom: +X, -X, +Y, -Y, +Z, -Z

6 rotational degrees of freedom:

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You must fix all the 12 degrees of freedom except the three transitional degrees of freedom (-X, -Y and -Z) in order to locate the work piece in the fixture. So, 9 degrees of freedom of the work piece need to be fixed by using the 3-2-1 method.

Fig 2.2 fixture set up-(3-2-1 on principle)

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2.3 CLAMPING

Once work piece is located, it is necessary to press it against locating surfaces and hold it there against the force acting upon it. The tool designer refers to this action as clamping and the mechanisms used for this action are known as clamps.

‘ Clamp should firmly hold the work piece without distorting it.
‘ Should overcome the maximum possible force exerted on work piece by using minimum clamping force
‘ Easy to operate
‘ Vibrations should tighten the cams and wedges in the clamp design (if any) and not loosen them

Fig 2.3 position of holding work piece

2.4Fixturing Functional Requirements

1) Stable resting,

2) Accurate localization.

3) support reinforcement,

4) stable clamping,

5) fore closure(or total restraint) and

6) Quality performance.

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The functions have strong precede the first five functions are required at the fixturing stage, and sequentially. When a work piece is placed into a fixture, it must first assume a stable resting against the gravity. Then, the locators should provide accurate localization. Next, supports are moved in place, and finally clamps are activated for the part immobilization (force-closure). The part location must be maintained in the process of instantiating clamps without work piece lift-off. The performance of the fixture is ultimately defined as work piece geometric error during the manufacturing stage. The geometric error is mainly determined by the fixture localization accuracy and the work piece static and elastic deformation during manufacturing. There are additional constraints to be satisfied such as interference-free and easy loading and unloading.

2.4.1 Design Consideration in Fixtures

The main frame of fixture must be strong enough so that deflection of the fixture is as minimum as possible. This deflection of fixture is caused because of forces of cutting, clamping of the work piece or clamping to the machine table. The main frame of the fixture should have the mass to prevent vibration and chatter.
‘ Frames may be built from simple sections so that frames may be fastened with screws or welded whenever necessary. Those parts of the frame that remain permanently with the fixture may be welded. Those parts that need frequent changing may be held with the screws.

‘ In the situation, where the body of fixture has complex shape, it may be cast from good grade of cast iron. All locator’s clamps should be easily visible to the operator. ‘

‘ Clamping should be fast enough and require least amount of effort.’

‘ Clamps should be arranged so that they are readily available and may be easily removed.’

‘ Clamps should be supported with springs so that clamps are held against the bolt head wherever possible.’
‘ Permitted to swing as far as it is necessary for removal of the work piece.

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PROBLEM DEFINATION:-

From literature it have been found that there is not any arc welding flexible fixtures available. It is planned to Design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

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3. DESIGN ASPECTS

3.1 Individual Design of flexible fixture parts

This section covered different aspects of design of arc welding fixture with cutting action.

3.1.1 Design of supporting frame

Frame is consist of uniform member (of circular section, angle section, channel section, square section etc.) joined together at their ends by riveting or welding.in case of our project welding fixture, we need a support structure of all other member like square slotted pate, clamping device and work piece plate which is required to welded.so it is easy to fabricate a square section plate frame by welding. So we select the frame as a hollow square cross section plate from Indian standard.
Selection of material for frame
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993) Fe 470 W Steel with a minimum tensile strength of 470 N/mm and of guaranteed fusion welding quality in real application of fe470 in clutch and free wheel clutch.

‘ Specification of frame material i.e. Fe 470
‘ Indian standard designation = Fe 470

‘ Tensile strength ( minimum) = 580 N/mm”

‘ Yield strength (minimum) = 430 N/mm”

‘ Minimum percentage elongation = 21

‘ Bending strength = 230 N/mm”

— Page – 23

Fig 3.1 Drawing of supporting frame

Now, assume that the frame is a simply supported beam carrying Uniform Distributed Load (U.D.L) as 10,000 Newton on 1300 mm length. A little consideration show that a frame is subjected to bending as well as static load. As shown in table no.1 various value of F.O.S. for various material based on Indian standard.

Material Steady load Live load Shock load

Cast iron 5 to 6 8 to 12 16 to 20

Wrought iron 4 7 10 to 15

Steel 5 8 12 to 16

Soft material and 6 9 15
alloys

Leather 9 12 15

Timber 7 10 to 15 20

Table no. 1 various value of F.O.S. for various material

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1) Frame subjecting to Static Load

Now assume factor of safety (F.O.S) = 5 (select from table no.1 for steel) Static Load (W) = 8000 N (Design load for fixture)

Design stress (”) = Yield strength / F.O.S

= 430/5

= 86 N/mm”

As per market evaluation we found standard cross section (50*50) for hollow square pipe.it capable for fixture as per loading condition.

So Area of cross section (A) = Hollow Square pipe

= 50*50

= 5 mm thick platen

Let we know that static stress

” = W/A

86 = 8000 /A
A = 8000/86

= 93.02 mm”

But, A= B”= 93.02

B = 9.64 mm > 50 mm hence safe in static loading.

2) Frame subjecting to bending Load

We know that the bending equation is given by

M/I = ”/Y = E/R

Where M = Bending moment acting at the given section

” = Bending stress

I = Moment of inertia of cross section about the neutral axis

Y = Distance from the neutral axis

— Page – 25

E = Young Modulus of elasticity of material

R = Radius of curvature of the beam

From above equation

Bending ” = M/I *Y

=M/Z

Where Z = section modulus = I / Y

Now assume that frame is a simply supported beam and also we know that Bending Moment of simply supported beam with U.D.L.

M = WL” / 8 (Equation for simply supported beam with U.D.L.)

Where W = U.D.L. on frame = 8,000N

L = Length of span (Frame) = 1300 mm

Hence M = 8,000*(1300)” ” 8

= 1690000000N*m

Now section modulus of square cross section

Z= (B4 – H4) ” 6B

= (504 – 404) ” 6*50

= 12300 mm”

Also bending ” = M”Z

= 1690000000 ” 12300

= 137.75 N/mm”

So bending stress ” = 137.75 N/mm” > 245 N/mm” (design bending stress) Hence it is prove that frame is safe in bending.

Final dimension of supporting frame

— Page – 26
Hollow square pipe cross section= 50*50 and 5mm thickness

Length of frame (L) = 1300 mm

Width of frame (W) = 400 mm

3.1.2 Design of vertical column

A machine part subjected to an axial compressive force is called strut. A strut may be horizontal, inclined, or even vertical. But a Vertical strut is known as a column. It has been observed that when a column is subjected to a compressive load and is gradually increased, a stage will reach when the column will be subjected to ultimate load. Beyond this, the column will fail by crushing and the load will be known as crushing load.

It has also been experienced, that sometimes, a compression member does not fail entirely by crushing, but also by bending i.e. buckling. If the load is gradually increased, the column will reach a stage, when it will start buckling. The load at which the column tends to buckle is called buckling load, critical load or crippling load and the column is said to have developed an elastic instability.

‘ Selection of material for vertical column
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993)We select the steel material Fe 330 as used for locomotive carriages and car structures, screw stock and other general engineering purpose.

Specification of vertical column material i.e. Fe 330
‘ Indian standard designation = Fe 330
‘ Tensile strength (minimum) = 330 N/mm”

‘ Yield strength (minimum) = 200 N/mm”

‘ Minimum percentage elongation = 26

‘ Crushing stress =330 N/mm”

‘ Young’s modulus = 0.21 * 106 N/mm”

‘ Area of cross section = 70*70 and 500 mm length

— Page – 27

Fig.3.2 drawing of vertical column

In actual practice, there are number of end condition for column. But in case our project parts as vertical column is a both ends fixed type square column.

‘ Maximum Crippling load capacity of column

Now we calculate maximum crippling load or buckling load by Rankine’s formula for column

Wc r= (”c * A) ” {1 + a (L/K)}

Where, Wcr= Crippling load

”c= Crushing stress

A = Cross sectional area of column

= 70 * 70

= 4900 mm”

a = Rankine’s constant = ”c/ (”*E)

= 1” 4500 (for mild steel)

L= Equivalent length of the column

— Page – 28
= l/2 (both ends fixed)

= 500/2

= 250

K=Least radius of gyration

=0.289 B (for square cross section) = 0.289 * 70 =20.23

Now,

Wcr= (330* 4900) ” {1 + (1” 4500 ) (250/20.23) }

= 1495215.823 N

= 1495.21 KN

So Maximum Crippling load capacity of column = 1495.21 KN

3.1.3Design of slotted plate

‘ Selection of slotted plate material

As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993). We select the steel material Fe 410 as used for specially used for High-strength Steel Plate.
‘ Specification of slotted plate material i.e. Fe 410

‘ Indian standard designation = Fe 410

‘ Tensile strength ( minimum) = 360 N/mm”

‘ Yield strength (minimum) = 225 N/mm”

‘ Minimum percentage elongation = 27

Area of cross section = 20*20 with 10 mm slot throughout length i.e. 750 mm and another plate is 1250 mm length

— Page – 29

Fig.3.3 drawing of slotted plate 1250 mm length

Fig.3.4 drawing of slotted plate 750 mm length

Now a slotted plate is design on its static strength so we assume that Factor of Safety (F.O.S) = 5 (select from table no.1 for steel)

”t = Tensile strength / F.O.S

= 360 / 5

= 72 N/mm2

— Page – 30
Also we know that ”t= W / A

72 = 8,000 / A
A = 8,000/ 72

= 111.11mm” But, A = B”

235.29= B”

B= 10.54 ~ 12 mm

Hence it is prove that frame is safe in static loading.

3.1.4 Design of shaft

A shaft is a rotating machine element which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and the resultant torque (or twisting moment) set up within the shaft permits the power to be transferred to various machines linked up to the shaft.

‘ Selection of shaft material

The material used for ordinary shaft is carbon steel of grades 40 C 8, 45 C 8, 50 C 4, 50 C 12. When a shaft of high strength is required, then an alloy steel such as nickel, nickel-chromium or chrome-vanadium steel is used. But as per our requirement is medium strength is needed, so we select ordinary steel of grade 50 C 4.

‘ Specification of shaft material i.e. 50 C 4.

‘ Indian standard designation = 50 C 4

‘ Ultimate tensile strength = 1080 N/mm”

‘ Yield strength =930 N/mm”

‘ Permissible tensile stress = 0.6”u

= 0.6 * 1080

— Page – 31

= 648 N/mm2

Permissible shear stress = 0.18”u

=0.18* 1080

= 194.4 N/mm2

As per market evaluation we found standard diameter (30 mm) for shaft. It capable for supporting frame as per loading condition.

Cross section of shaft = 30 mm diameter

= 100 mm length

A little consideration we show that in our project shaft is subjecting only twisting moment hence we design the shaft on the pure twisting moment equation.

Fig. 3.5 drawing of shaft

Maximum torque capacity of shaft

T = ” / 16 *”*d3

=” / 16*194.4*(30)3

= 1030599.47Nm

=1030.59 KNm

Hence Maximum torque capacity of shaft = 1030.59 KNm

— Page – 32

3.1.5 Design of Circular Indexing plate and Indexing pin

Main objective of indexing plate in flexible fixture is to rotate the frame at various angle i.e. Up to 180 degree of rotation and also fixed at a desired angle as per requirement of welder. A handle is provided on circular indexing plate it provide rotating movement of frame. By using an indexing pin (circular pin) frame can be fixed at required position. A hole provided on circumference of circular plate at regular interval i.e. (180/7) approximate 25 degree of each hole.by means of indexing pin attached in a Hole frame can be fixed as per requirement.

Fig. 3.6 drawing of circular indexing plate

— Page – 33

Fig.3.7 drawing of indexing pin

3.1.6 Design of clamping device and pin locator

‘ Make or buy decision for clamping device and pin locator

In case in fixture it’s required to fixed the work piece on the frame of fixture. This objective is done by using clamps and locating pin. In flexible fixture work piece i.e. plate are fixed by four clamping device and pin locator. But problems is that if clamps are make or buy from market.

If we make i.e. produced clamp in work shop so it is costly because we not produced in mass production. As well as it’s difficult to give accurate size of clamps. Also full facility of machining, casting and super finishing is not available in our work shop. As discussed above difficulty in making clamp and locating pin we purchase the required clamps and locating pin from market.

Fig.3.8 drawing of pin locator

— Page – 34

Fig.3.9 drawing of clamping device

— Page – 35

3.1.7 Summary of part design

As discussed above various parts of arc welding fixture as summarized in table no.2.

Sr. No. Name of Dimension No. of parts Material
part
1 Supporting L=1300 mm 1 Fe 470
frame W=400 mm
2 Vertical L = 500 mm 2 Fe 330
column 50*50square
cross section
3 Slotted plate 1 L= 1250 mm 2 Fe 410
4 Slotted plate 2 L= 750 mm 3 Fe 410
5 Shaft L= 100 mm 2 50 C4
D = 15 mm
6 Indexing plate D = 400 mm 1 Fe 290
t = 10 mm
with 7 hole
7 Clamp – 4 –
8 Locating pin – 4 –
Table no. 2 summary of parts for arc welding fixture

— Page – 36
3.2 Assembly of welding flexible fixture.

After all discussed above parts assemble and fabricate arc welding flexible fixture as shown fig. no 3.10

Fig.3.10 2D drawing of welding flexible fixture assembly

— Page – 37

Fig.3.11 3D drawing of welding flexible fixture assembly

— Page – 38

4. RESULTS AND CONCLUSION

Manufacture accurately interchangeable parts. Fixtures are specially designed so that large numbers of components can assembled identically, and to ensure interchangeability of components.

Facilitate economical production of engineering components.

The main functions of a welding fixture are:

Griping
A work piece in the predetermined manner of firmness and location.

Holding

Components rigid and prevent movement during welding in order to impart greater productivity and part accuracy.

Supporting and locating
Every component (part) to ensure that teach is welded within the specified limits.

Positioning

Components accurately and maintain relationship and alignment between the holder and the work piece correctly to perform on the work piece a welding operation.

Results:-

‘ welding with the help of arc welding fixtures reduced time for production of the component and also reduce the fatigue effect on worker due to ergonomically convenient for the operation

‘ with help of fixture effective clamping is done more accurate than the conventional method.

‘ the circular indexing plate gives rotational movement for the front side, topside weld more easier than the conventional method in which worker have to move the work piece as per the weld position.

— Page 39

‘ the hand cutter provide the facility to cut the frame or bar while the work piece clamped on the fixture

‘ in conventional method first worker to arrange accurately before weld of frame while in fixture with help of locator work piece automatically locating

‘ this fixtures increases the productivity, accuracy, reliability

Futures scope:-

In the above arc welding flexible fixtures various futures scope are as under

‘ Provide power driven or automatic movement of the circular indexing plate which reduces the worker fatigue.
‘ Here we only indexing up to the180 degree while with help of other clamping arrangement 360 degree indexing possible.
‘ The clamping surface are of the flat which only locate the flat work piece for provide V-shape at the end also possible for the circular work piece.
‘ To provide the scale on the slotted plate we adjust the clamp as per work piece size

— Page 40

5. REFERENCES:

Research paper:

‘ Design of Fixtures: A Review By Nisarg Parmar IJARIIE-ISSN(O)-2395-4396
http://www.ijariie.com
‘ A Review on Design of Fixtures by Shailesh S.Pachbhai & Laukik P.Raut International Journal of Engineering Research and General Science Volume 2, Issue 2, Feb-Mar 2014 ISSN 2091-2730
‘ Design of Welding Fixtures and Positiners
Prof. S.N.Shinde, Siddharth Kshirsagar, Aniruddha Patil, Tejas Parge, Ritesh Lomte
International Journal of Engineering Research and General Science Volume 2, Issue 5, August-September, 2014 ISSN 2091-2730

Books:

1) Text book of Machine Design by r.s khurmi and j.k gupta s chand publication

2) Text book of Production technology by r.k.jain Khanna publication

3) Production technology by p.c sharma s chand publication

4) Machine Tool Design by N. K. Mehta

— Page 41

A
PROJECT REPORT

ON

‘Design and manufacturing of flexible fixture for different frame welding’

Submitted by
1) Gurjar Jignesh (130210119047)
2) Zala Pushparajsinh (130210119125)
3) Katariya Piyush (140213119014)
4) Radhanpura Nadim (140213119021)

In fulfilment for the award of the degree

Of

BACHELOR OF ENGINEERING

In
Mechanical engineering

Government Engineering Collage, Bhavnagar
Gujarat Technology University, Ahmedabad

— Page 1

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Gurjar Jigneshkumar Maganbhai under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Radhanpura Nadim under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Zala Pushparajsinh, under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Katariya Piyush, under my guidance in fulfilment
Of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

ABSTRACT

In modern industrial work number of various material in different shape and size are required to develop various component for different application. Welding is one of the important fabrication process in product development work. Development of flexible fixtures for welding process is today’s requirement is reduce operation time, increase production and high quality of production.

It is planned to design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

Key words: – Welding, Flexible Fixture.

— Page 3

ACKNOWLEDGEMENT

I am using this opportunity to express my gratitude to everyone who supported me throughout the course of this final year project. I am thankful for their aspiring guidance, invaluably constructive criticism and friendly advice during the project work. I am sincerely grateful to them for sharing their truthful and illuminating views on a number of issues related to the project.

I express my warm thanks to Prof. N.K Tank for their support and excellent guidance from starting to the end of our final year project at Government Engineering Collage, Bhavnagar. Also thankful to the Mechanical Department for their active cooperation and support whose encouragement, continuous guidance, helpful nature, new suggestion and ideas were invaluable for accomplishment of this work.

Thank you

Gurjar Jignesh

Zala Pushparajsinh

Katariya Piyush

Radhanpura Nadim

— Page 4

LIST OF TABLES

Table No. Table Description Page No.
Table no.1 various value of F.O.S. for various material 24
Table no.2 Summary of part design 36

— PAGE 5

LIST OF FIGURES

Figure No. Figure Description Page No.
Fig 1.1 (a) Jig (B) Fixture 10
Fig 1.2 Manual metal arc welding process 11
Fig 2.1 Principle of fixture (3-2-1) 18
Fig 2.2 Fixture set up-(3-2-1 on principle) 19
Fig 2.3 Holding work piece position 20
Fig 3.1 Drawing of supporting frame 24
Fig 3.2 Drawing of vertical column 28
Fig 3.3 Drawing of slotted plate 1250 mm 30
Fig 3.4 Drawing of slotted plate 750 mm 32
Fig 3.5 Drawing of shaft 33
Fig 3.6 Drawing of circular indexing plate 34
Fig 3.7 Drawing of indexing pin 35

— Page 6

Figure No. Figure Description Page No.
Fig 3.8 Drawing of Pin locator 35
Fig 3.9 Drawing of Clamping device 35
Fig 3.10 2D drawing of welding flexible fixture assembly 37
Fig 3.11 3D drawing of welding flexible fixture assembly 38

— Page 7

TABLE OF CONTENTS

Sr.no TITLE PAGE NO.
1 Abstract 3
2 Acknowledgement 4
3 List of Tables 5
4 List of Figures 6
INTRODUCTION 10
1.1 Jig and fixture
1.2 Fixture for arc welding process
a) Role of fixture in arc welding process
b) Advantages of fixture used in arc welding process
1.3 Fundamental principles of Arc weld Fixtures design
LITERATURE REVIEW 14
2.1 Steps of Fabrication fixture design
2.2 Location- Six pin (3-2-1) locating principle
2.3 Clamping
2.4 Fixturing Functional Requirements

— R Page 8
Sr.no DESIGN ASPECTS 23

3.1 Individual design of arc welding fixture
3.1.1 Design of supporting frame
3.1.2 Design of vertical column
3.1.3 Design of slotted plate
3.1.4 Design of shaft
3.1.5 Design of circular indexing plate and pin
3.1.6 Design of clamping device
3.1.7 Summary of part design
3.2 drawing and 3-D model of assembly

4. RESULTS & CONCLUSION 39

5. REFERENCES 41

— Page 9

1. INTRODUCTION

1.1 Jigs and fixture:-

The fixture is a special tool for holding a work piece in proper position during manufacturing operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in manufacturing process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages. To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators.

Jig: is a fixture with an additional feature of tool guidance

Fixture: fixture, being used in machine shop, are strong and rigid mechanical devices which enable easy, quick and consistently accurate locating. Supporting and clamping, blanks against cutting tools and result faster and accurate machining with consistent quality, functional ability and interchangeability.

(A) Jig (B) Fixture

Fig. 1.1

— Page 10
1.2 Fixture in arc welding process:-

As the manufacturing costs of the metal-working industry are nowadays mainly determined by the costs of labor with accuracy, many industries are compelled to rationalize their manufacturing methods by partially and fully mechanized production processes. In the field of welding engineering where a consistently excellent quality with an optimum productivity is a must, automation aspects are consequently taken into account.

Fig.1.2 Manual metal arc welding process (MMAW)

Figure shows manual metal arc welding (MMAW), in this case manual electrode welding. The control of the electrode and/or the arc is carried out manually. The filler metal (the consumable electrode) is also fed manually to the welding point.
a) Role of flexible fixture in arc welding processes:-

‘ Hold the parts in correct position.’
‘ Assist and control the joining process.”
‘ Mechanically or Alignment of work pieces
o ‘
‘ Tooling for hot processes should withstand heat and accelerate or retard flow of heat’Hot fixtures should have thermal expansion coefficient so that it remains functional.

— Page 11
Advantages of fixture used in arc welding processes:-


‘ To assure high accuracy of welding parts.’

‘ Provide for interchangeability in assembly.

‘ Enable heavy and complex parts to be weld.’

‘ Reduce distortion.

‘ Saving in labor time and less kills require.’

‘ Use improve the safety and reduced accidents.’

‘ Produce Interchangeable and Quality parts
‘ Reduction cost of manufacturing”

1.3 Fundamental principles of Arc weld flexible Fixtures design:-

a) Locating points: Good facilities should be provided for locating the work. The article to be machined must be easily inserted and quickly taken out from the fixture so that no time is wasted in placing the work piece in position to perform operations. The position of work piece should be accurate with respect to tool guiding in the jig or setting elements in fixture.

b) fool proof: It can be defined as ‘the incorporation of design feature in the fixture that will make it possible to lead the work into fixture, in an improper position but will not interface with loading and unloading the work piece” there are many fool proofing device, such as fooling pegs, blocks or pins which clear correctly position parts but prevent incorrectly loaded parts from entering the fixture body.
c) Simplicity surface: machining on the work piece must be clearly visible to the worker. He should not be required to bend is neck for seeing the work piece or work surface.
d) Weight of weld fixtures: It should be easy to handle smaller in size and low cost in regard to amount of material used without sacrificing rigidity and stiffness.

— Page 12

e) Materials for jigs and fixtures: Usually made of hardened materials to avoid frequent damage and to resist wear.

Example- MS, Cast iron, Die steel, CS, HSS.

f) Clamping device: It should be as simple as possible without sacrificing effectiveness. The strength of clamp should be such that not only to hold the work piece firmly in place but also to take the Thermal stresses produced during welding, when designing the weld fixtures.

— Page 13
2. LITERATURE REVIEW

The fixture is a special tool for holding a work piece in proper position during Fabrication operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in Fabrication process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages.

To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators. Clamping has to be appropriately planned at the stage of machining fixture design. The design of a fixture is a highly complex and intuitive process, which require knowledge. Fabrication Fixture design plays an important role at the setup planning phase. Proper fixture design is crucial for developing product quality in different terms of accuracy, surface finish and precision of the machined parts in existing design the Fabrication fixture set up is done manually, so the aim of this project is to replace with Fabrication fixture to save time for loading and unloading of component. Fabrication fixture provides the manufacturer for flexibility in holding forces and to optimize design for Fabrication operation as well as process function ability.

2.1 Steps of Fabrication fixture design

Successful fixture designs begin with a logical and systematic plan. With a complete analysis of the

Fixture’s functional requirements, very few design problems occur. When they do, chances are some

Design requirements were forgotten or underestimated. The work piece, processing, tooling and

Available machine tools may affect the extent of planning needed. Preliminary analysis may take from

Few hours up to several days for more complicated fixture designs. Fixture design is a five-step

Problem-solving process. The following is a detailed analysis of each step.

— Page 14
Step 1: Define Requirements

To initiate the Fabrication fixture-design process, clearly state the problem to be solved or needs to be met. State these requirements as broadly as possible, but specifically enough to define the scope of the design project. The designer should ask some basic questions: Is the new tooling required for first-time production or to improve existing production

Step 2: Gather/Analyze Information

Collect all relevant data and assemble it for evaluation. The main sources of information are the part print process sheets. Make sure that part documents and records are current. For example, verify that the shop print is the current revision, and the processing information is up-to-date. Check with the design department for pending part revisions. An important part of the evaluation process is note taking. Complete, accurate notes allow designers to record important information. With these notes, they should be able to fill in all items on the “Checklist for Design Considerations.” All ideas, thoughts, observations, and any other data about the part or fixture are then available for later reference. It is always better to have too many ideas about a particular design than too few. Four categories of design considerations need to be taken into account at this time: work piece specifications, operation variables, availability of equipment, and personnel. These categories, while separately covered here, are actually

Step 3: Develop Several Options

This phase of the fixture-design process requires the most creativity. A typical work-piece can be located and clamped several different ways. The natural tendency is to think of one solution, then develop and refine it while blocking out other, perhaps better solutions. A designer should brainstorm for several good tooling alternatives, not just choose one path right away. During this phase, the designer’s goal should be adding options, not discarding them. In the interest of economy, alternative designs should be developed only far enough to make sure they are feasible and to do a cost estimate. The designer usually starts with at least three options: permanent, modular, and general-purpose work holding. Each of these options has many clamping and locating options of its own.

— Page 15
The more standard locating and clamping. Devices that a designer is familiar with, the more creative he can be. Devices that a designer is familiar with, the more creative he can be. Areas for locating a part include flat exterior surfaces (machined and machined), cylindrical and curved exterior surfaces. The exact procedure used to construct the preliminary design sketches is not as important as the items sketched. Generally, the preliminary sketch should start should start with the part to be fixtured. The required locating and supporting elements, including a base, should be the next items added. Then sketch the clamping devices. Finally, add the machine tool and cutting tools. Sketching these items together helps identify any problem areas in the design of the complete fixture.

Step 4: Choose the Best Option

The total cost to manufacture a part is the sum of per-piece run cost, setup cost, and tooling cost. Expressed as a These variables are described below with sample values from three tooling options: a modular fixture, a permanent fixture, and a hydraulically powered permanent fixture.

Step 5: Implement the Design

The final phase of the fixture-design process consists of turning the chosen design approach into reality. Final details are decided, final drawings are made, and the tooling is built and tested. The following guidelines should be considered during the final-design process to make the fixture less costly while improving its efficiency. These rules are a mix of practical considerations, sound design practices, and common sense

(I)Use standard components:

The economies of standard parts apply to tooling components as well as to manufactured products. Standard, readily available components include clamps, locators, supports, studs, nuts, pins and a host of other elements. Most designers would never think of having the shop make cap screws, bolts or nuts for a fixture. Likewise, no standard tooling components should be made in-house. The first rule of economic design is: Never build any component you can buy. Commercially available tooling components are manufactured in large quantities for much greater economy. In most cases, the
Cost of buying a component is less than 20% of the cost of making it.

— Page 16
(II)Use prefinished materials:

Prefinished and preformed materials should be used where possible to lower costs and simplify construction. These materials include precision-ground flat stock, drill rod, structural sections, cast tooling sections, precast tooling bodies, tooling plates, and other standard preformed materials. Including these materials in a design both reduces the design time and lowers the labor cost.

(III)Eliminate finishing operations:

Finishing operations should never be performed for cosmetic purposes. Making a Fabrication fixture look better often can double its cost. Here are a few suggestions to keep in mind with regard to finishing operations.

The most cost-effective tooling tolerance for a locator is approximately 30% to 50% of the work piece’s tolerance. Tighter tolerances normally add extra cost to the tooling with little benefit to the process. Where necessary, tighter tolerances can be used, but tighter tolerances do not necessarily result in a better fixture, only a more expensive one.

2.2 MEANING OF LOCATION

The location refers to the establishment of a desired relationship between the work piece and the jigs or fixture correctness of location directly influences the accuracy of the finished product. To position the work piece w.r.t. to tool, to ensure precision in machining. Dimensional and positional relationship between work piece and tool device to establish and maintain position of a part in a jig or fixture.
The jigs and fixtures are desired so that all undesirable movements of the work piece can be restricted. Determination of the locating points and clamping of the work piece serve to restrict movements of the component in any direction, while setting it in a particular pre-decided position relative to the jig. Before deciding the locating points it is advisable to find out the all possible degrees of freedom of the work piece. Then some of the degrees of freedom or all of them are restrained by making suitable arrangements. These arrangements are called locators. These are described in details in location principle.
— Page 17
2.2.1 Six pin (3-2-1) locating principle

A work piece free in space can move in an infinite number of directions. For analysis, this motion can be broken down into twelve directional movements, or “degrees of freedom.” All twelve degrees of freedom must be restricted to ensure proper referencing of a work piece.

Fig. 2.1. 3-2-1 locating principle
As shown in Figure 2.02, the twelve degrees of freedom all relate to the central axes of the work piece. Notice the six axial degrees of freedom and six radial degrees of freedom. The axial degrees of freedom permit straight-line movement in both directions along the three principal axes, shown as x, y, and z. The radial degrees of freedom permit rotational movement, in both clockwise and counter clockwise radial directions, around the same three axes. The devices that restrict a work piece’s movement are the locators. The locators, therefore, must be strong enough to maintain the position of the work piece and to resist the cutting forces. This fact also points out a crucial element in work holder design: locators, not clamps, must hold the work piece against the cutting forces. Locators provide a positive stop for the work piece. Placed against the stop, the work piece cannot move. Clamps, on the other hand, rely only upon friction between the clamp and the clamped surface to hold the work piece. Sufficient force could move the work piece. Clamps are only intended to hold the work piece against the locators.

6 translational degrees of freedom: +X, -X, +Y, -Y, +Z, -Z

6 rotational degrees of freedom:

— Page 18

You must fix all the 12 degrees of freedom except the three transitional degrees of freedom (-X, -Y and -Z) in order to locate the work piece in the fixture. So, 9 degrees of freedom of the work piece need to be fixed by using the 3-2-1 method.

Fig 2.2 fixture set up-(3-2-1 on principle)

— Page 19

2.3 CLAMPING

Once work piece is located, it is necessary to press it against locating surfaces and hold it there against the force acting upon it. The tool designer refers to this action as clamping and the mechanisms used for this action are known as clamps.

‘ Clamp should firmly hold the work piece without distorting it.
‘ Should overcome the maximum possible force exerted on work piece by using minimum clamping force
‘ Easy to operate
‘ Vibrations should tighten the cams and wedges in the clamp design (if any) and not loosen them

Fig 2.3 position of holding work piece

2.4Fixturing Functional Requirements

1) Stable resting,

2) Accurate localization.

3) support reinforcement,

4) stable clamping,

5) fore closure(or total restraint) and

6) Quality performance.

— Page 20

The functions have strong precede the first five functions are required at the fixturing stage, and sequentially. When a work piece is placed into a fixture, it must first assume a stable resting against the gravity. Then, the locators should provide accurate localization. Next, supports are moved in place, and finally clamps are activated for the part immobilization (force-closure). The part location must be maintained in the process of instantiating clamps without work piece lift-off. The performance of the fixture is ultimately defined as work piece geometric error during the manufacturing stage. The geometric error is mainly determined by the fixture localization accuracy and the work piece static and elastic deformation during manufacturing. There are additional constraints to be satisfied such as interference-free and easy loading and unloading.

2.4.1 Design Consideration in Fixtures

The main frame of fixture must be strong enough so that deflection of the fixture is as minimum as possible. This deflection of fixture is caused because of forces of cutting, clamping of the work piece or clamping to the machine table. The main frame of the fixture should have the mass to prevent vibration and chatter.
‘ Frames may be built from simple sections so that frames may be fastened with screws or welded whenever necessary. Those parts of the frame that remain permanently with the fixture may be welded. Those parts that need frequent changing may be held with the screws.

‘ In the situation, where the body of fixture has complex shape, it may be cast from good grade of cast iron. All locator’s clamps should be easily visible to the operator. ‘

‘ Clamping should be fast enough and require least amount of effort.’

‘ Clamps should be arranged so that they are readily available and may be easily removed.’

‘ Clamps should be supported with springs so that clamps are held against the bolt head wherever possible.’
‘ Permitted to swing as far as it is necessary for removal of the work piece.

— Page 21


PROBLEM DEFINATION:-

From literature it have been found that there is not any arc welding flexible fixtures available. It is planned to Design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

— Page 22

3. DESIGN ASPECTS

3.1 Individual Design of flexible fixture parts

This section covered different aspects of design of arc welding fixture with cutting action.

3.1.1 Design of supporting frame

Frame is consist of uniform member (of circular section, angle section, channel section, square section etc.) joined together at their ends by riveting or welding.in case of our project welding fixture, we need a support structure of all other member like square slotted pate, clamping device and work piece plate which is required to welded.so it is easy to fabricate a square section plate frame by welding. So we select the frame as a hollow square cross section plate from Indian standard.
Selection of material for frame
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993) Fe 470 W Steel with a minimum tensile strength of 470 N/mm and of guaranteed fusion welding quality in real application of fe470 in clutch and free wheel clutch.

‘ Specification of frame material i.e. Fe 470
‘ Indian standard designation = Fe 470

‘ Tensile strength ( minimum) = 580 N/mm”

‘ Yield strength (minimum) = 430 N/mm”

‘ Minimum percentage elongation = 21

‘ Bending strength = 230 N/mm”

— Page – 23

Fig 3.1 Drawing of supporting frame

Now, assume that the frame is a simply supported beam carrying Uniform Distributed Load (U.D.L) as 10,000 Newton on 1300 mm length. A little consideration show that a frame is subjected to bending as well as static load. As shown in table no.1 various value of F.O.S. for various material based on Indian standard.

Material Steady load Live load Shock load

Cast iron 5 to 6 8 to 12 16 to 20

Wrought iron 4 7 10 to 15

Steel 5 8 12 to 16

Soft material and 6 9 15
alloys

Leather 9 12 15

Timber 7 10 to 15 20

Table no. 1 various value of F.O.S. for various material

— Page 24

1) Frame subjecting to Static Load

Now assume factor of safety (F.O.S) = 5 (select from table no.1 for steel) Static Load (W) = 8000 N (Design load for fixture)

Design stress (”) = Yield strength / F.O.S

= 430/5

= 86 N/mm”

As per market evaluation we found standard cross section (50*50) for hollow square pipe.it capable for fixture as per loading condition.

So Area of cross section (A) = Hollow Square pipe

= 50*50

= 5 mm thick platen

Let we know that static stress

” = W/A

86 = 8000 /A
A = 8000/86

= 93.02 mm”

But, A= B”= 93.02

B = 9.64 mm > 50 mm hence safe in static loading.

2) Frame subjecting to bending Load

We know that the bending equation is given by

M/I = ”/Y = E/R

Where M = Bending moment acting at the given section

” = Bending stress

I = Moment of inertia of cross section about the neutral axis

Y = Distance from the neutral axis

— Page – 25

E = Young Modulus of elasticity of material

R = Radius of curvature of the beam

From above equation

Bending ” = M/I *Y

=M/Z

Where Z = section modulus = I / Y

Now assume that frame is a simply supported beam and also we know that Bending Moment of simply supported beam with U.D.L.

M = WL” / 8 (Equation for simply supported beam with U.D.L.)

Where W = U.D.L. on frame = 8,000N

L = Length of span (Frame) = 1300 mm

Hence M = 8,000*(1300)” ” 8

= 1690000000N*m

Now section modulus of square cross section

Z= (B4 – H4) ” 6B

= (504 – 404) ” 6*50

= 12300 mm”

Also bending ” = M”Z

= 1690000000 ” 12300

= 137.75 N/mm”

So bending stress ” = 137.75 N/mm” > 245 N/mm” (design bending stress) Hence it is prove that frame is safe in bending.

Final dimension of supporting frame

— Page – 26
Hollow square pipe cross section= 50*50 and 5mm thickness

Length of frame (L) = 1300 mm

Width of frame (W) = 400 mm

3.1.2 Design of vertical column

A machine part subjected to an axial compressive force is called strut. A strut may be horizontal, inclined, or even vertical. But a Vertical strut is known as a column. It has been observed that when a column is subjected to a compressive load and is gradually increased, a stage will reach when the column will be subjected to ultimate load. Beyond this, the column will fail by crushing and the load will be known as crushing load.

It has also been experienced, that sometimes, a compression member does not fail entirely by crushing, but also by bending i.e. buckling. If the load is gradually increased, the column will reach a stage, when it will start buckling. The load at which the column tends to buckle is called buckling load, critical load or crippling load and the column is said to have developed an elastic instability.

‘ Selection of material for vertical column
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993)We select the steel material Fe 330 as used for locomotive carriages and car structures, screw stock and other general engineering purpose.

Specification of vertical column material i.e. Fe 330
‘ Indian standard designation = Fe 330
‘ Tensile strength (minimum) = 330 N/mm”

‘ Yield strength (minimum) = 200 N/mm”

‘ Minimum percentage elongation = 26

‘ Crushing stress =330 N/mm”

‘ Young’s modulus = 0.21 * 106 N/mm”

‘ Area of cross section = 70*70 and 500 mm length

— Page – 27

Fig.3.2 drawing of vertical column

In actual practice, there are number of end condition for column. But in case our project parts as vertical column is a both ends fixed type square column.

‘ Maximum Crippling load capacity of column

Now we calculate maximum crippling load or buckling load by Rankine’s formula for column

Wc r= (”c * A) ” {1 + a (L/K)}

Where, Wcr= Crippling load

”c= Crushing stress

A = Cross sectional area of column

= 70 * 70

= 4900 mm”

a = Rankine’s constant = ”c/ (”*E)

= 1” 4500 (for mild steel)

L= Equivalent length of the column

— Page – 28
= l/2 (both ends fixed)

= 500/2

= 250

K=Least radius of gyration

=0.289 B (for square cross section) = 0.289 * 70 =20.23

Now,

Wcr= (330* 4900) ” {1 + (1” 4500 ) (250/20.23) }

= 1495215.823 N

= 1495.21 KN

So Maximum Crippling load capacity of column = 1495.21 KN

3.1.3Design of slotted plate

‘ Selection of slotted plate material

As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993). We select the steel material Fe 410 as used for specially used for High-strength Steel Plate.
‘ Specification of slotted plate material i.e. Fe 410

‘ Indian standard designation = Fe 410

‘ Tensile strength ( minimum) = 360 N/mm”

‘ Yield strength (minimum) = 225 N/mm”

‘ Minimum percentage elongation = 27

Area of cross section = 20*20 with 10 mm slot throughout length i.e. 750 mm and another plate is 1250 mm length

— Page – 29

Fig.3.3 drawing of slotted plate 1250 mm length

Fig.3.4 drawing of slotted plate 750 mm length

Now a slotted plate is design on its static strength so we assume that Factor of Safety (F.O.S) = 5 (select from table no.1 for steel)

”t = Tensile strength / F.O.S

= 360 / 5

= 72 N/mm2

— Page – 30
Also we know that ”t= W / A

72 = 8,000 / A
A = 8,000/ 72

= 111.11mm” But, A = B”

235.29= B”

B= 10.54 ~ 12 mm

Hence it is prove that frame is safe in static loading.

3.1.4 Design of shaft

A shaft is a rotating machine element which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and the resultant torque (or twisting moment) set up within the shaft permits the power to be transferred to various machines linked up to the shaft.

‘ Selection of shaft material

The material used for ordinary shaft is carbon steel of grades 40 C 8, 45 C 8, 50 C 4, 50 C 12. When a shaft of high strength is required, then an alloy steel such as nickel, nickel-chromium or chrome-vanadium steel is used. But as per our requirement is medium strength is needed, so we select ordinary steel of grade 50 C 4.

‘ Specification of shaft material i.e. 50 C 4.

‘ Indian standard designation = 50 C 4

‘ Ultimate tensile strength = 1080 N/mm”

‘ Yield strength =930 N/mm”

‘ Permissible tensile stress = 0.6”u

= 0.6 * 1080

— Page – 31

= 648 N/mm2

Permissible shear stress = 0.18”u

=0.18* 1080

= 194.4 N/mm2

As per market evaluation we found standard diameter (30 mm) for shaft. It capable for supporting frame as per loading condition.

Cross section of shaft = 30 mm diameter

= 100 mm length

A little consideration we show that in our project shaft is subjecting only twisting moment hence we design the shaft on the pure twisting moment equation.

Fig. 3.5 drawing of shaft

Maximum torque capacity of shaft

T = ” / 16 *”*d3

=” / 16*194.4*(30)3

= 1030599.47Nm

=1030.59 KNm

Hence Maximum torque capacity of shaft = 1030.59 KNm

— Page – 32

3.1.5 Design of Circular Indexing plate and Indexing pin

Main objective of indexing plate in flexible fixture is to rotate the frame at various angle i.e. Up to 180 degree of rotation and also fixed at a desired angle as per requirement of welder. A handle is provided on circular indexing plate it provide rotating movement of frame. By using an indexing pin (circular pin) frame can be fixed at required position. A hole provided on circumference of circular plate at regular interval i.e. (180/7) approximate 25 degree of each hole.by means of indexing pin attached in a Hole frame can be fixed as per requirement.

Fig. 3.6 drawing of circular indexing plate

— Page – 33

Fig.3.7 drawing of indexing pin

3.1.6 Design of clamping device and pin locator

‘ Make or buy decision for clamping device and pin locator

In case in fixture it’s required to fixed the work piece on the frame of fixture. This objective is done by using clamps and locating pin. In flexible fixture work piece i.e. plate are fixed by four clamping device and pin locator. But problems is that if clamps are make or buy from market.

If we make i.e. produced clamp in work shop so it is costly because we not produced in mass production. As well as it’s difficult to give accurate size of clamps. Also full facility of machining, casting and super finishing is not available in our work shop. As discussed above difficulty in making clamp and locating pin we purchase the required clamps and locating pin from market.

Fig.3.8 drawing of pin locator

— Page – 34

Fig.3.9 drawing of clamping device

— Page – 35

3.1.7 Summary of part design

As discussed above various parts of arc welding fixture as summarized in table no.2.

Sr. No. Name of Dimension No. of parts Material
part
1 Supporting L=1300 mm 1 Fe 470
frame W=400 mm
2 Vertical L = 500 mm 2 Fe 330
column 50*50square
cross section
3 Slotted plate 1 L= 1250 mm 2 Fe 410
4 Slotted plate 2 L= 750 mm 3 Fe 410
5 Shaft L= 100 mm 2 50 C4
D = 15 mm
6 Indexing plate D = 400 mm 1 Fe 290
t = 10 mm
with 7 hole
7 Clamp – 4 –
8 Locating pin – 4 –
Table no. 2 summary of parts for arc welding fixture

— Page – 36
3.2 Assembly of welding flexible fixture.

After all discussed above parts assemble and fabricate arc welding flexible fixture as shown fig. no 3.10

Fig.3.10 2D drawing of welding flexible fixture assembly

— Page – 37

Fig.3.11 3D drawing of welding flexible fixture assembly

— Page – 38

4. RESULTS AND CONCLUSION

Manufacture accurately interchangeable parts. Fixtures are specially designed so that large numbers of components can assembled identically, and to ensure interchangeability of components.

Facilitate economical production of engineering components.

The main functions of a welding fixture are:

Griping
A work piece in the predetermined manner of firmness and location.

Holding

Components rigid and prevent movement during welding in order to impart greater productivity and part accuracy.

Supporting and locating
Every component (part) to ensure that teach is welded within the specified limits.

Positioning

Components accurately and maintain relationship and alignment between the holder and the work piece correctly to perform on the work piece a welding operation.

Results:-

‘ welding with the help of arc welding fixtures reduced time for production of the component and also reduce the fatigue effect on worker due to ergonomically convenient for the operation

‘ with help of fixture effective clamping is done more accurate than the conventional method.

‘ the circular indexing plate gives rotational movement for the front side, topside weld more easier than the conventional method in which worker have to move the work piece as per the weld position.

— Page 39

‘ the hand cutter provide the facility to cut the frame or bar while the work piece clamped on the fixture

‘ in conventional method first worker to arrange accurately before weld of frame while in fixture with help of locator work piece automatically locating

‘ this fixtures increases the productivity, accuracy, reliability

Futures scope:-

In the above arc welding flexible fixtures various futures scope are as under

‘ Provide power driven or automatic movement of the circular indexing plate which reduces the worker fatigue.
‘ Here we only indexing up to the180 degree while with help of other clamping arrangement 360 degree indexing possible.
‘ The clamping surface are of the flat which only locate the flat work piece for provide V-shape at the end also possible for the circular work piece.
‘ To provide the scale on the slotted plate we adjust the clamp as per work piece size

— Page 40

5. REFERENCES:

Research paper:

‘ Design of Fixtures: A Review By Nisarg Parmar IJARIIE-ISSN(O)-2395-4396
http://www.ijariie.com
‘ A Review on Design of Fixtures by Shailesh S.Pachbhai & Laukik P.Raut International Journal of Engineering Research and General Science Volume 2, Issue 2, Feb-Mar 2014 ISSN 2091-2730
‘ Design of Welding Fixtures and Positiners
Prof. S.N.Shinde, Siddharth Kshirsagar, Aniruddha Patil, Tejas Parge, Ritesh Lomte
International Journal of Engineering Research and General Science Volume 2, Issue 5, August-September, 2014 ISSN 2091-2730

Books:

1) Text book of Machine Design by r.s khurmi and j.k gupta s chand publication

2) Text book of Production technology by r.k.jain Khanna publication

3) Production technology by p.c sharma s chand publication

4) Machine Tool Design by N. K. Mehta

— Page 41

A
PROJECT REPORT

ON

‘Design and manufacturing of flexible fixture for different frame welding’

Submitted by
1) Gurjar Jignesh (130210119047)
2) Zala Pushparajsinh (130210119125)
3) Katariya Piyush (140213119014)
4) Radhanpura Nadim (140213119021)

In fulfilment for the award of the degree

Of

BACHELOR OF ENGINEERING

In
Mechanical engineering

Government Engineering Collage, Bhavnagar
Gujarat Technology University, Ahmedabad

— Page 1

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Gurjar Jigneshkumar Maganbhai under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Radhanpura Nadim under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Zala Pushparajsinh, under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Katariya Piyush, under my guidance in fulfilment
Of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

ABSTRACT

In modern industrial work number of various material in different shape and size are required to develop various component for different application. Welding is one of the important fabrication process in product development work. Development of flexible fixtures for welding process is today’s requirement is reduce operation time, increase production and high quality of production.

It is planned to design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

Key words: – Welding, Flexible Fixture.

— Page 3

ACKNOWLEDGEMENT

I am using this opportunity to express my gratitude to everyone who supported me throughout the course of this final year project. I am thankful for their aspiring guidance, invaluably constructive criticism and friendly advice during the project work. I am sincerely grateful to them for sharing their truthful and illuminating views on a number of issues related to the project.

I express my warm thanks to Prof. N.K Tank for their support and excellent guidance from starting to the end of our final year project at Government Engineering Collage, Bhavnagar. Also thankful to the Mechanical Department for their active cooperation and support whose encouragement, continuous guidance, helpful nature, new suggestion and ideas were invaluable for accomplishment of this work.

Thank you

Gurjar Jignesh

Zala Pushparajsinh

Katariya Piyush

Radhanpura Nadim

— Page 4

LIST OF TABLES

Table No. Table Description Page No.
Table no.1 various value of F.O.S. for various material 24
Table no.2 Summary of part design 36

— PAGE 5

LIST OF FIGURES

Figure No. Figure Description Page No.
Fig 1.1 (a) Jig (B) Fixture 10
Fig 1.2 Manual metal arc welding process 11
Fig 2.1 Principle of fixture (3-2-1) 18
Fig 2.2 Fixture set up-(3-2-1 on principle) 19
Fig 2.3 Holding work piece position 20
Fig 3.1 Drawing of supporting frame 24
Fig 3.2 Drawing of vertical column 28
Fig 3.3 Drawing of slotted plate 1250 mm 30
Fig 3.4 Drawing of slotted plate 750 mm 32
Fig 3.5 Drawing of shaft 33
Fig 3.6 Drawing of circular indexing plate 34
Fig 3.7 Drawing of indexing pin 35

— Page 6

Figure No. Figure Description Page No.
Fig 3.8 Drawing of Pin locator 35
Fig 3.9 Drawing of Clamping device 35
Fig 3.10 2D drawing of welding flexible fixture assembly 37
Fig 3.11 3D drawing of welding flexible fixture assembly 38

— Page 7

TABLE OF CONTENTS

Sr.no TITLE PAGE NO.
1 Abstract 3
2 Acknowledgement 4
3 List of Tables 5
4 List of Figures 6
INTRODUCTION 10
1.1 Jig and fixture
1.2 Fixture for arc welding process
a) Role of fixture in arc welding process
b) Advantages of fixture used in arc welding process
1.3 Fundamental principles of Arc weld Fixtures design
LITERATURE REVIEW 14
2.1 Steps of Fabrication fixture design
2.2 Location- Six pin (3-2-1) locating principle
2.3 Clamping
2.4 Fixturing Functional Requirements

— R Page 8
Sr.no DESIGN ASPECTS 23

3.1 Individual design of arc welding fixture
3.1.1 Design of supporting frame
3.1.2 Design of vertical column
3.1.3 Design of slotted plate
3.1.4 Design of shaft
3.1.5 Design of circular indexing plate and pin
3.1.6 Design of clamping device
3.1.7 Summary of part design
3.2 drawing and 3-D model of assembly

4. RESULTS & CONCLUSION 39

5. REFERENCES 41

— Page 9

1. INTRODUCTION

1.1 Jigs and fixture:-

The fixture is a special tool for holding a work piece in proper position during manufacturing operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in manufacturing process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages. To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators.

Jig: is a fixture with an additional feature of tool guidance

Fixture: fixture, being used in machine shop, are strong and rigid mechanical devices which enable easy, quick and consistently accurate locating. Supporting and clamping, blanks against cutting tools and result faster and accurate machining with consistent quality, functional ability and interchangeability.

(A) Jig (B) Fixture

Fig. 1.1

— Page 10
1.2 Fixture in arc welding process:-

As the manufacturing costs of the metal-working industry are nowadays mainly determined by the costs of labor with accuracy, many industries are compelled to rationalize their manufacturing methods by partially and fully mechanized production processes. In the field of welding engineering where a consistently excellent quality with an optimum productivity is a must, automation aspects are consequently taken into account.

Fig.1.2 Manual metal arc welding process (MMAW)

Figure shows manual metal arc welding (MMAW), in this case manual electrode welding. The control of the electrode and/or the arc is carried out manually. The filler metal (the consumable electrode) is also fed manually to the welding point.
a) Role of flexible fixture in arc welding processes:-

‘ Hold the parts in correct position.’
‘ Assist and control the joining process.”
‘ Mechanically or Alignment of work pieces
o ‘
‘ Tooling for hot processes should withstand heat and accelerate or retard flow of heat’Hot fixtures should have thermal expansion coefficient so that it remains functional.

— Page 11
Advantages of fixture used in arc welding processes:-


‘ To assure high accuracy of welding parts.’

‘ Provide for interchangeability in assembly.

‘ Enable heavy and complex parts to be weld.’

‘ Reduce distortion.

‘ Saving in labor time and less kills require.’

‘ Use improve the safety and reduced accidents.’

‘ Produce Interchangeable and Quality parts
‘ Reduction cost of manufacturing”

1.3 Fundamental principles of Arc weld flexible Fixtures design:-

a) Locating points: Good facilities should be provided for locating the work. The article to be machined must be easily inserted and quickly taken out from the fixture so that no time is wasted in placing the work piece in position to perform operations. The position of work piece should be accurate with respect to tool guiding in the jig or setting elements in fixture.

b) fool proof: It can be defined as ‘the incorporation of design feature in the fixture that will make it possible to lead the work into fixture, in an improper position but will not interface with loading and unloading the work piece” there are many fool proofing device, such as fooling pegs, blocks or pins which clear correctly position parts but prevent incorrectly loaded parts from entering the fixture body.
c) Simplicity surface: machining on the work piece must be clearly visible to the worker. He should not be required to bend is neck for seeing the work piece or work surface.
d) Weight of weld fixtures: It should be easy to handle smaller in size and low cost in regard to amount of material used without sacrificing rigidity and stiffness.

— Page 12

e) Materials for jigs and fixtures: Usually made of hardened materials to avoid frequent damage and to resist wear.

Example- MS, Cast iron, Die steel, CS, HSS.

f) Clamping device: It should be as simple as possible without sacrificing effectiveness. The strength of clamp should be such that not only to hold the work piece firmly in place but also to take the Thermal stresses produced during welding, when designing the weld fixtures.

— Page 13
2. LITERATURE REVIEW

The fixture is a special tool for holding a work piece in proper position during Fabrication operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in Fabrication process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages.

To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators. Clamping has to be appropriately planned at the stage of machining fixture design. The design of a fixture is a highly complex and intuitive process, which require knowledge. Fabrication Fixture design plays an important role at the setup planning phase. Proper fixture design is crucial for developing product quality in different terms of accuracy, surface finish and precision of the machined parts in existing design the Fabrication fixture set up is done manually, so the aim of this project is to replace with Fabrication fixture to save time for loading and unloading of component. Fabrication fixture provides the manufacturer for flexibility in holding forces and to optimize design for Fabrication operation as well as process function ability.

2.1 Steps of Fabrication fixture design

Successful fixture designs begin with a logical and systematic plan. With a complete analysis of the

Fixture’s functional requirements, very few design problems occur. When they do, chances are some

Design requirements were forgotten or underestimated. The work piece, processing, tooling and

Available machine tools may affect the extent of planning needed. Preliminary analysis may take from

Few hours up to several days for more complicated fixture designs. Fixture design is a five-step

Problem-solving process. The following is a detailed analysis of each step.

— Page 14
Step 1: Define Requirements

To initiate the Fabrication fixture-design process, clearly state the problem to be solved or needs to be met. State these requirements as broadly as possible, but specifically enough to define the scope of the design project. The designer should ask some basic questions: Is the new tooling required for first-time production or to improve existing production

Step 2: Gather/Analyze Information

Collect all relevant data and assemble it for evaluation. The main sources of information are the part print process sheets. Make sure that part documents and records are current. For example, verify that the shop print is the current revision, and the processing information is up-to-date. Check with the design department for pending part revisions. An important part of the evaluation process is note taking. Complete, accurate notes allow designers to record important information. With these notes, they should be able to fill in all items on the “Checklist for Design Considerations.” All ideas, thoughts, observations, and any other data about the part or fixture are then available for later reference. It is always better to have too many ideas about a particular design than too few. Four categories of design considerations need to be taken into account at this time: work piece specifications, operation variables, availability of equipment, and personnel. These categories, while separately covered here, are actually

Step 3: Develop Several Options

This phase of the fixture-design process requires the most creativity. A typical work-piece can be located and clamped several different ways. The natural tendency is to think of one solution, then develop and refine it while blocking out other, perhaps better solutions. A designer should brainstorm for several good tooling alternatives, not just choose one path right away. During this phase, the designer’s goal should be adding options, not discarding them. In the interest of economy, alternative designs should be developed only far enough to make sure they are feasible and to do a cost estimate. The designer usually starts with at least three options: permanent, modular, and general-purpose work holding. Each of these options has many clamping and locating options of its own.

— Page 15
The more standard locating and clamping. Devices that a designer is familiar with, the more creative he can be. Devices that a designer is familiar with, the more creative he can be. Areas for locating a part include flat exterior surfaces (machined and machined), cylindrical and curved exterior surfaces. The exact procedure used to construct the preliminary design sketches is not as important as the items sketched. Generally, the preliminary sketch should start should start with the part to be fixtured. The required locating and supporting elements, including a base, should be the next items added. Then sketch the clamping devices. Finally, add the machine tool and cutting tools. Sketching these items together helps identify any problem areas in the design of the complete fixture.

Step 4: Choose the Best Option

The total cost to manufacture a part is the sum of per-piece run cost, setup cost, and tooling cost. Expressed as a These variables are described below with sample values from three tooling options: a modular fixture, a permanent fixture, and a hydraulically powered permanent fixture.

Step 5: Implement the Design

The final phase of the fixture-design process consists of turning the chosen design approach into reality. Final details are decided, final drawings are made, and the tooling is built and tested. The following guidelines should be considered during the final-design process to make the fixture less costly while improving its efficiency. These rules are a mix of practical considerations, sound design practices, and common sense

(I)Use standard components:

The economies of standard parts apply to tooling components as well as to manufactured products. Standard, readily available components include clamps, locators, supports, studs, nuts, pins and a host of other elements. Most designers would never think of having the shop make cap screws, bolts or nuts for a fixture. Likewise, no standard tooling components should be made in-house. The first rule of economic design is: Never build any component you can buy. Commercially available tooling components are manufactured in large quantities for much greater economy. In most cases, the
Cost of buying a component is less than 20% of the cost of making it.

— Page 16
(II)Use prefinished materials:

Prefinished and preformed materials should be used where possible to lower costs and simplify construction. These materials include precision-ground flat stock, drill rod, structural sections, cast tooling sections, precast tooling bodies, tooling plates, and other standard preformed materials. Including these materials in a design both reduces the design time and lowers the labor cost.

(III)Eliminate finishing operations:

Finishing operations should never be performed for cosmetic purposes. Making a Fabrication fixture look better often can double its cost. Here are a few suggestions to keep in mind with regard to finishing operations.

The most cost-effective tooling tolerance for a locator is approximately 30% to 50% of the work piece’s tolerance. Tighter tolerances normally add extra cost to the tooling with little benefit to the process. Where necessary, tighter tolerances can be used, but tighter tolerances do not necessarily result in a better fixture, only a more expensive one.

2.2 MEANING OF LOCATION

The location refers to the establishment of a desired relationship between the work piece and the jigs or fixture correctness of location directly influences the accuracy of the finished product. To position the work piece w.r.t. to tool, to ensure precision in machining. Dimensional and positional relationship between work piece and tool device to establish and maintain position of a part in a jig or fixture.
The jigs and fixtures are desired so that all undesirable movements of the work piece can be restricted. Determination of the locating points and clamping of the work piece serve to restrict movements of the component in any direction, while setting it in a particular pre-decided position relative to the jig. Before deciding the locating points it is advisable to find out the all possible degrees of freedom of the work piece. Then some of the degrees of freedom or all of them are restrained by making suitable arrangements. These arrangements are called locators. These are described in details in location principle.
— Page 17
2.2.1 Six pin (3-2-1) locating principle

A work piece free in space can move in an infinite number of directions. For analysis, this motion can be broken down into twelve directional movements, or “degrees of freedom.” All twelve degrees of freedom must be restricted to ensure proper referencing of a work piece.

Fig. 2.1. 3-2-1 locating principle
As shown in Figure 2.02, the twelve degrees of freedom all relate to the central axes of the work piece. Notice the six axial degrees of freedom and six radial degrees of freedom. The axial degrees of freedom permit straight-line movement in both directions along the three principal axes, shown as x, y, and z. The radial degrees of freedom permit rotational movement, in both clockwise and counter clockwise radial directions, around the same three axes. The devices that restrict a work piece’s movement are the locators. The locators, therefore, must be strong enough to maintain the position of the work piece and to resist the cutting forces. This fact also points out a crucial element in work holder design: locators, not clamps, must hold the work piece against the cutting forces. Locators provide a positive stop for the work piece. Placed against the stop, the work piece cannot move. Clamps, on the other hand, rely only upon friction between the clamp and the clamped surface to hold the work piece. Sufficient force could move the work piece. Clamps are only intended to hold the work piece against the locators.

6 translational degrees of freedom: +X, -X, +Y, -Y, +Z, -Z

6 rotational degrees of freedom:

— Page 18

You must fix all the 12 degrees of freedom except the three transitional degrees of freedom (-X, -Y and -Z) in order to locate the work piece in the fixture. So, 9 degrees of freedom of the work piece need to be fixed by using the 3-2-1 method.

Fig 2.2 fixture set up-(3-2-1 on principle)

— Page 19

2.3 CLAMPING

Once work piece is located, it is necessary to press it against locating surfaces and hold it there against the force acting upon it. The tool designer refers to this action as clamping and the mechanisms used for this action are known as clamps.

‘ Clamp should firmly hold the work piece without distorting it.
‘ Should overcome the maximum possible force exerted on work piece by using minimum clamping force
‘ Easy to operate
‘ Vibrations should tighten the cams and wedges in the clamp design (if any) and not loosen them

Fig 2.3 position of holding work piece

2.4Fixturing Functional Requirements

1) Stable resting,

2) Accurate localization.

3) support reinforcement,

4) stable clamping,

5) fore closure(or total restraint) and

6) Quality performance.

— Page 20

The functions have strong precede the first five functions are required at the fixturing stage, and sequentially. When a work piece is placed into a fixture, it must first assume a stable resting against the gravity. Then, the locators should provide accurate localization. Next, supports are moved in place, and finally clamps are activated for the part immobilization (force-closure). The part location must be maintained in the process of instantiating clamps without work piece lift-off. The performance of the fixture is ultimately defined as work piece geometric error during the manufacturing stage. The geometric error is mainly determined by the fixture localization accuracy and the work piece static and elastic deformation during manufacturing. There are additional constraints to be satisfied such as interference-free and easy loading and unloading.

2.4.1 Design Consideration in Fixtures

The main frame of fixture must be strong enough so that deflection of the fixture is as minimum as possible. This deflection of fixture is caused because of forces of cutting, clamping of the work piece or clamping to the machine table. The main frame of the fixture should have the mass to prevent vibration and chatter.
‘ Frames may be built from simple sections so that frames may be fastened with screws or welded whenever necessary. Those parts of the frame that remain permanently with the fixture may be welded. Those parts that need frequent changing may be held with the screws.

‘ In the situation, where the body of fixture has complex shape, it may be cast from good grade of cast iron. All locator’s clamps should be easily visible to the operator. ‘

‘ Clamping should be fast enough and require least amount of effort.’

‘ Clamps should be arranged so that they are readily available and may be easily removed.’

‘ Clamps should be supported with springs so that clamps are held against the bolt head wherever possible.’
‘ Permitted to swing as far as it is necessary for removal of the work piece.

— Page 21


PROBLEM DEFINATION:-

From literature it have been found that there is not any arc welding flexible fixtures available. It is planned to Design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

— Page 22

3. DESIGN ASPECTS

3.1 Individual Design of flexible fixture parts

This section covered different aspects of design of arc welding fixture with cutting action.

3.1.1 Design of supporting frame

Frame is consist of uniform member (of circular section, angle section, channel section, square section etc.) joined together at their ends by riveting or welding.in case of our project welding fixture, we need a support structure of all other member like square slotted pate, clamping device and work piece plate which is required to welded.so it is easy to fabricate a square section plate frame by welding. So we select the frame as a hollow square cross section plate from Indian standard.
Selection of material for frame
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993) Fe 470 W Steel with a minimum tensile strength of 470 N/mm and of guaranteed fusion welding quality in real application of fe470 in clutch and free wheel clutch.

‘ Specification of frame material i.e. Fe 470
‘ Indian standard designation = Fe 470

‘ Tensile strength ( minimum) = 580 N/mm”

‘ Yield strength (minimum) = 430 N/mm”

‘ Minimum percentage elongation = 21

‘ Bending strength = 230 N/mm”

— Page – 23

Fig 3.1 Drawing of supporting frame

Now, assume that the frame is a simply supported beam carrying Uniform Distributed Load (U.D.L) as 10,000 Newton on 1300 mm length. A little consideration show that a frame is subjected to bending as well as static load. As shown in table no.1 various value of F.O.S. for various material based on Indian standard.

Material Steady load Live load Shock load

Cast iron 5 to 6 8 to 12 16 to 20

Wrought iron 4 7 10 to 15

Steel 5 8 12 to 16

Soft material and 6 9 15
alloys

Leather 9 12 15

Timber 7 10 to 15 20

Table no. 1 various value of F.O.S. for various material

— Page 24

1) Frame subjecting to Static Load

Now assume factor of safety (F.O.S) = 5 (select from table no.1 for steel) Static Load (W) = 8000 N (Design load for fixture)

Design stress (”) = Yield strength / F.O.S

= 430/5

= 86 N/mm”

As per market evaluation we found standard cross section (50*50) for hollow square pipe.it capable for fixture as per loading condition.

So Area of cross section (A) = Hollow Square pipe

= 50*50

= 5 mm thick platen

Let we know that static stress

” = W/A

86 = 8000 /A
A = 8000/86

= 93.02 mm”

But, A= B”= 93.02

B = 9.64 mm > 50 mm hence safe in static loading.

2) Frame subjecting to bending Load

We know that the bending equation is given by

M/I = ”/Y = E/R

Where M = Bending moment acting at the given section

” = Bending stress

I = Moment of inertia of cross section about the neutral axis

Y = Distance from the neutral axis

— Page – 25

E = Young Modulus of elasticity of material

R = Radius of curvature of the beam

From above equation

Bending ” = M/I *Y

=M/Z

Where Z = section modulus = I / Y

Now assume that frame is a simply supported beam and also we know that Bending Moment of simply supported beam with U.D.L.

M = WL” / 8 (Equation for simply supported beam with U.D.L.)

Where W = U.D.L. on frame = 8,000N

L = Length of span (Frame) = 1300 mm

Hence M = 8,000*(1300)” ” 8

= 1690000000N*m

Now section modulus of square cross section

Z= (B4 – H4) ” 6B

= (504 – 404) ” 6*50

= 12300 mm”

Also bending ” = M”Z

= 1690000000 ” 12300

= 137.75 N/mm”

So bending stress ” = 137.75 N/mm” > 245 N/mm” (design bending stress) Hence it is prove that frame is safe in bending.

Final dimension of supporting frame

— Page – 26
Hollow square pipe cross section= 50*50 and 5mm thickness

Length of frame (L) = 1300 mm

Width of frame (W) = 400 mm

3.1.2 Design of vertical column

A machine part subjected to an axial compressive force is called strut. A strut may be horizontal, inclined, or even vertical. But a Vertical strut is known as a column. It has been observed that when a column is subjected to a compressive load and is gradually increased, a stage will reach when the column will be subjected to ultimate load. Beyond this, the column will fail by crushing and the load will be known as crushing load.

It has also been experienced, that sometimes, a compression member does not fail entirely by crushing, but also by bending i.e. buckling. If the load is gradually increased, the column will reach a stage, when it will start buckling. The load at which the column tends to buckle is called buckling load, critical load or crippling load and the column is said to have developed an elastic instability.

‘ Selection of material for vertical column
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993)We select the steel material Fe 330 as used for locomotive carriages and car structures, screw stock and other general engineering purpose.

Specification of vertical column material i.e. Fe 330
‘ Indian standard designation = Fe 330
‘ Tensile strength (minimum) = 330 N/mm”

‘ Yield strength (minimum) = 200 N/mm”

‘ Minimum percentage elongation = 26

‘ Crushing stress =330 N/mm”

‘ Young’s modulus = 0.21 * 106 N/mm”

‘ Area of cross section = 70*70 and 500 mm length

— Page – 27

Fig.3.2 drawing of vertical column

In actual practice, there are number of end condition for column. But in case our project parts as vertical column is a both ends fixed type square column.

‘ Maximum Crippling load capacity of column

Now we calculate maximum crippling load or buckling load by Rankine’s formula for column

Wc r= (”c * A) ” {1 + a (L/K)}

Where, Wcr= Crippling load

”c= Crushing stress

A = Cross sectional area of column

= 70 * 70

= 4900 mm”

a = Rankine’s constant = ”c/ (”*E)

= 1” 4500 (for mild steel)

L= Equivalent length of the column

— Page – 28
= l/2 (both ends fixed)

= 500/2

= 250

K=Least radius of gyration

=0.289 B (for square cross section) = 0.289 * 70 =20.23

Now,

Wcr= (330* 4900) ” {1 + (1” 4500 ) (250/20.23) }

= 1495215.823 N

= 1495.21 KN

So Maximum Crippling load capacity of column = 1495.21 KN

3.1.3Design of slotted plate

‘ Selection of slotted plate material

As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993). We select the steel material Fe 410 as used for specially used for High-strength Steel Plate.
‘ Specification of slotted plate material i.e. Fe 410

‘ Indian standard designation = Fe 410

‘ Tensile strength ( minimum) = 360 N/mm”

‘ Yield strength (minimum) = 225 N/mm”

‘ Minimum percentage elongation = 27

Area of cross section = 20*20 with 10 mm slot throughout length i.e. 750 mm and another plate is 1250 mm length

— Page – 29

Fig.3.3 drawing of slotted plate 1250 mm length

Fig.3.4 drawing of slotted plate 750 mm length

Now a slotted plate is design on its static strength so we assume that Factor of Safety (F.O.S) = 5 (select from table no.1 for steel)

”t = Tensile strength / F.O.S

= 360 / 5

= 72 N/mm2

— Page – 30
Also we know that ”t= W / A

72 = 8,000 / A
A = 8,000/ 72

= 111.11mm” But, A = B”

235.29= B”

B= 10.54 ~ 12 mm

Hence it is prove that frame is safe in static loading.

3.1.4 Design of shaft

A shaft is a rotating machine element which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and the resultant torque (or twisting moment) set up within the shaft permits the power to be transferred to various machines linked up to the shaft.

‘ Selection of shaft material

The material used for ordinary shaft is carbon steel of grades 40 C 8, 45 C 8, 50 C 4, 50 C 12. When a shaft of high strength is required, then an alloy steel such as nickel, nickel-chromium or chrome-vanadium steel is used. But as per our requirement is medium strength is needed, so we select ordinary steel of grade 50 C 4.

‘ Specification of shaft material i.e. 50 C 4.

‘ Indian standard designation = 50 C 4

‘ Ultimate tensile strength = 1080 N/mm”

‘ Yield strength =930 N/mm”

‘ Permissible tensile stress = 0.6”u

= 0.6 * 1080

— Page – 31

= 648 N/mm2

Permissible shear stress = 0.18”u

=0.18* 1080

= 194.4 N/mm2

As per market evaluation we found standard diameter (30 mm) for shaft. It capable for supporting frame as per loading condition.

Cross section of shaft = 30 mm diameter

= 100 mm length

A little consideration we show that in our project shaft is subjecting only twisting moment hence we design the shaft on the pure twisting moment equation.

Fig. 3.5 drawing of shaft

Maximum torque capacity of shaft

T = ” / 16 *”*d3

=” / 16*194.4*(30)3

= 1030599.47Nm

=1030.59 KNm

Hence Maximum torque capacity of shaft = 1030.59 KNm

— Page – 32

3.1.5 Design of Circular Indexing plate and Indexing pin

Main objective of indexing plate in flexible fixture is to rotate the frame at various angle i.e. Up to 180 degree of rotation and also fixed at a desired angle as per requirement of welder. A handle is provided on circular indexing plate it provide rotating movement of frame. By using an indexing pin (circular pin) frame can be fixed at required position. A hole provided on circumference of circular plate at regular interval i.e. (180/7) approximate 25 degree of each hole.by means of indexing pin attached in a Hole frame can be fixed as per requirement.

Fig. 3.6 drawing of circular indexing plate

— Page – 33

Fig.3.7 drawing of indexing pin

3.1.6 Design of clamping device and pin locator

‘ Make or buy decision for clamping device and pin locator

In case in fixture it’s required to fixed the work piece on the frame of fixture. This objective is done by using clamps and locating pin. In flexible fixture work piece i.e. plate are fixed by four clamping device and pin locator. But problems is that if clamps are make or buy from market.

If we make i.e. produced clamp in work shop so it is costly because we not produced in mass production. As well as it’s difficult to give accurate size of clamps. Also full facility of machining, casting and super finishing is not available in our work shop. As discussed above difficulty in making clamp and locating pin we purchase the required clamps and locating pin from market.

Fig.3.8 drawing of pin locator

— Page – 34

Fig.3.9 drawing of clamping device

— Page – 35

3.1.7 Summary of part design

As discussed above various parts of arc welding fixture as summarized in table no.2.

Sr. No. Name of Dimension No. of parts Material
part
1 Supporting L=1300 mm 1 Fe 470
frame W=400 mm
2 Vertical L = 500 mm 2 Fe 330
column 50*50square
cross section
3 Slotted plate 1 L= 1250 mm 2 Fe 410
4 Slotted plate 2 L= 750 mm 3 Fe 410
5 Shaft L= 100 mm 2 50 C4
D = 15 mm
6 Indexing plate D = 400 mm 1 Fe 290
t = 10 mm
with 7 hole
7 Clamp – 4 –
8 Locating pin – 4 –
Table no. 2 summary of parts for arc welding fixture

— Page – 36
3.2 Assembly of welding flexible fixture.

After all discussed above parts assemble and fabricate arc welding flexible fixture as shown fig. no 3.10

Fig.3.10 2D drawing of welding flexible fixture assembly

— Page – 37

Fig.3.11 3D drawing of welding flexible fixture assembly

— Page – 38

4. RESULTS AND CONCLUSION

Manufacture accurately interchangeable parts. Fixtures are specially designed so that large numbers of components can assembled identically, and to ensure interchangeability of components.

Facilitate economical production of engineering components.

The main functions of a welding fixture are:

Griping
A work piece in the predetermined manner of firmness and location.

Holding

Components rigid and prevent movement during welding in order to impart greater productivity and part accuracy.

Supporting and locating
Every component (part) to ensure that teach is welded within the specified limits.

Positioning

Components accurately and maintain relationship and alignment between the holder and the work piece correctly to perform on the work piece a welding operation.

Results:-

‘ welding with the help of arc welding fixtures reduced time for production of the component and also reduce the fatigue effect on worker due to ergonomically convenient for the operation

‘ with help of fixture effective clamping is done more accurate than the conventional method.

‘ the circular indexing plate gives rotational movement for the front side, topside weld more easier than the conventional method in which worker have to move the work piece as per the weld position.

— Page 39

‘ the hand cutter provide the facility to cut the frame or bar while the work piece clamped on the fixture

‘ in conventional method first worker to arrange accurately before weld of frame while in fixture with help of locator work piece automatically locating

‘ this fixtures increases the productivity, accuracy, reliability

Futures scope:-

In the above arc welding flexible fixtures various futures scope are as under

‘ Provide power driven or automatic movement of the circular indexing plate which reduces the worker fatigue.
‘ Here we only indexing up to the180 degree while with help of other clamping arrangement 360 degree indexing possible.
‘ The clamping surface are of the flat which only locate the flat work piece for provide V-shape at the end also possible for the circular work piece.
‘ To provide the scale on the slotted plate we adjust the clamp as per work piece size

— Page 40

5. REFERENCES:

Research paper:

‘ Design of Fixtures: A Review By Nisarg Parmar IJARIIE-ISSN(O)-2395-4396
http://www.ijariie.com
‘ A Review on Design of Fixtures by Shailesh S.Pachbhai & Laukik P.Raut International Journal of Engineering Research and General Science Volume 2, Issue 2, Feb-Mar 2014 ISSN 2091-2730
‘ Design of Welding Fixtures and Positiners
Prof. S.N.Shinde, Siddharth Kshirsagar, Aniruddha Patil, Tejas Parge, Ritesh Lomte
International Journal of Engineering Research and General Science Volume 2, Issue 5, August-September, 2014 ISSN 2091-2730

Books:

1) Text book of Machine Design by r.s khurmi and j.k gupta s chand publication

2) Text book of Production technology by r.k.jain Khanna publication

3) Production technology by p.c sharma s chand publication

4) Machine Tool Design by N. K. Mehta

— Page 41

A
PROJECT REPORT

ON

‘Design and manufacturing of flexible fixture for different frame welding’

Submitted by
1) Gurjar Jignesh (130210119047)
2) Zala Pushparajsinh (130210119125)
3) Katariya Piyush (140213119014)
4) Radhanpura Nadim (140213119021)

In fulfilment for the award of the degree

Of

BACHELOR OF ENGINEERING

In
Mechanical engineering

Government Engineering Collage, Bhavnagar
Gujarat Technology University, Ahmedabad

— Page 1

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Gurjar Jigneshkumar Maganbhai under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Radhanpura Nadim under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Zala Pushparajsinh, under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Katariya Piyush, under my guidance in fulfilment
Of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

ABSTRACT

In modern industrial work number of various material in different shape and size are required to develop various component for different application. Welding is one of the important fabrication process in product development work. Development of flexible fixtures for welding process is today’s requirement is reduce operation time, increase production and high quality of production.

It is planned to design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

Key words: – Welding, Flexible Fixture.

— Page 3

ACKNOWLEDGEMENT

I am using this opportunity to express my gratitude to everyone who supported me throughout the course of this final year project. I am thankful for their aspiring guidance, invaluably constructive criticism and friendly advice during the project work. I am sincerely grateful to them for sharing their truthful and illuminating views on a number of issues related to the project.

I express my warm thanks to Prof. N.K Tank for their support and excellent guidance from starting to the end of our final year project at Government Engineering Collage, Bhavnagar. Also thankful to the Mechanical Department for their active cooperation and support whose encouragement, continuous guidance, helpful nature, new suggestion and ideas were invaluable for accomplishment of this work.

Thank you

Gurjar Jignesh

Zala Pushparajsinh

Katariya Piyush

Radhanpura Nadim

— Page 4

LIST OF TABLES

Table No. Table Description Page No.
Table no.1 various value of F.O.S. for various material 24
Table no.2 Summary of part design 36

— PAGE 5

LIST OF FIGURES

Figure No. Figure Description Page No.
Fig 1.1 (a) Jig (B) Fixture 10
Fig 1.2 Manual metal arc welding process 11
Fig 2.1 Principle of fixture (3-2-1) 18
Fig 2.2 Fixture set up-(3-2-1 on principle) 19
Fig 2.3 Holding work piece position 20
Fig 3.1 Drawing of supporting frame 24
Fig 3.2 Drawing of vertical column 28
Fig 3.3 Drawing of slotted plate 1250 mm 30
Fig 3.4 Drawing of slotted plate 750 mm 32
Fig 3.5 Drawing of shaft 33
Fig 3.6 Drawing of circular indexing plate 34
Fig 3.7 Drawing of indexing pin 35

— Page 6

Figure No. Figure Description Page No.
Fig 3.8 Drawing of Pin locator 35
Fig 3.9 Drawing of Clamping device 35
Fig 3.10 2D drawing of welding flexible fixture assembly 37
Fig 3.11 3D drawing of welding flexible fixture assembly 38

— Page 7

TABLE OF CONTENTS

Sr.no TITLE PAGE NO.
1 Abstract 3
2 Acknowledgement 4
3 List of Tables 5
4 List of Figures 6
INTRODUCTION 10
1.1 Jig and fixture
1.2 Fixture for arc welding process
a) Role of fixture in arc welding process
b) Advantages of fixture used in arc welding process
1.3 Fundamental principles of Arc weld Fixtures design
LITERATURE REVIEW 14
2.1 Steps of Fabrication fixture design
2.2 Location- Six pin (3-2-1) locating principle
2.3 Clamping
2.4 Fixturing Functional Requirements

— R Page 8
Sr.no DESIGN ASPECTS 23

3.1 Individual design of arc welding fixture
3.1.1 Design of supporting frame
3.1.2 Design of vertical column
3.1.3 Design of slotted plate
3.1.4 Design of shaft
3.1.5 Design of circular indexing plate and pin
3.1.6 Design of clamping device
3.1.7 Summary of part design
3.2 drawing and 3-D model of assembly

4. RESULTS & CONCLUSION 39

5. REFERENCES 41

— Page 9

1. INTRODUCTION

1.1 Jigs and fixture:-

The fixture is a special tool for holding a work piece in proper position during manufacturing operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in manufacturing process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages. To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators.

Jig: is a fixture with an additional feature of tool guidance

Fixture: fixture, being used in machine shop, are strong and rigid mechanical devices which enable easy, quick and consistently accurate locating. Supporting and clamping, blanks against cutting tools and result faster and accurate machining with consistent quality, functional ability and interchangeability.

(A) Jig (B) Fixture

Fig. 1.1

— Page 10
1.2 Fixture in arc welding process:-

As the manufacturing costs of the metal-working industry are nowadays mainly determined by the costs of labor with accuracy, many industries are compelled to rationalize their manufacturing methods by partially and fully mechanized production processes. In the field of welding engineering where a consistently excellent quality with an optimum productivity is a must, automation aspects are consequently taken into account.

Fig.1.2 Manual metal arc welding process (MMAW)

Figure shows manual metal arc welding (MMAW), in this case manual electrode welding. The control of the electrode and/or the arc is carried out manually. The filler metal (the consumable electrode) is also fed manually to the welding point.
a) Role of flexible fixture in arc welding processes:-

‘ Hold the parts in correct position.’
‘ Assist and control the joining process.”
‘ Mechanically or Alignment of work pieces
o ‘
‘ Tooling for hot processes should withstand heat and accelerate or retard flow of heat’Hot fixtures should have thermal expansion coefficient so that it remains functional.

— Page 11
Advantages of fixture used in arc welding processes:-


‘ To assure high accuracy of welding parts.’

‘ Provide for interchangeability in assembly.

‘ Enable heavy and complex parts to be weld.’

‘ Reduce distortion.

‘ Saving in labor time and less kills require.’

‘ Use improve the safety and reduced accidents.’

‘ Produce Interchangeable and Quality parts
‘ Reduction cost of manufacturing”

1.3 Fundamental principles of Arc weld flexible Fixtures design:-

a) Locating points: Good facilities should be provided for locating the work. The article to be machined must be easily inserted and quickly taken out from the fixture so that no time is wasted in placing the work piece in position to perform operations. The position of work piece should be accurate with respect to tool guiding in the jig or setting elements in fixture.

b) fool proof: It can be defined as ‘the incorporation of design feature in the fixture that will make it possible to lead the work into fixture, in an improper position but will not interface with loading and unloading the work piece” there are many fool proofing device, such as fooling pegs, blocks or pins which clear correctly position parts but prevent incorrectly loaded parts from entering the fixture body.
c) Simplicity surface: machining on the work piece must be clearly visible to the worker. He should not be required to bend is neck for seeing the work piece or work surface.
d) Weight of weld fixtures: It should be easy to handle smaller in size and low cost in regard to amount of material used without sacrificing rigidity and stiffness.

— Page 12

e) Materials for jigs and fixtures: Usually made of hardened materials to avoid frequent damage and to resist wear.

Example- MS, Cast iron, Die steel, CS, HSS.

f) Clamping device: It should be as simple as possible without sacrificing effectiveness. The strength of clamp should be such that not only to hold the work piece firmly in place but also to take the Thermal stresses produced during welding, when designing the weld fixtures.

— Page 13
2. LITERATURE REVIEW

The fixture is a special tool for holding a work piece in proper position during Fabrication operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in Fabrication process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages.

To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators. Clamping has to be appropriately planned at the stage of machining fixture design. The design of a fixture is a highly complex and intuitive process, which require knowledge. Fabrication Fixture design plays an important role at the setup planning phase. Proper fixture design is crucial for developing product quality in different terms of accuracy, surface finish and precision of the machined parts in existing design the Fabrication fixture set up is done manually, so the aim of this project is to replace with Fabrication fixture to save time for loading and unloading of component. Fabrication fixture provides the manufacturer for flexibility in holding forces and to optimize design for Fabrication operation as well as process function ability.

2.1 Steps of Fabrication fixture design

Successful fixture designs begin with a logical and systematic plan. With a complete analysis of the

Fixture’s functional requirements, very few design problems occur. When they do, chances are some

Design requirements were forgotten or underestimated. The work piece, processing, tooling and

Available machine tools may affect the extent of planning needed. Preliminary analysis may take from

Few hours up to several days for more complicated fixture designs. Fixture design is a five-step

Problem-solving process. The following is a detailed analysis of each step.

— Page 14
Step 1: Define Requirements

To initiate the Fabrication fixture-design process, clearly state the problem to be solved or needs to be met. State these requirements as broadly as possible, but specifically enough to define the scope of the design project. The designer should ask some basic questions: Is the new tooling required for first-time production or to improve existing production

Step 2: Gather/Analyze Information

Collect all relevant data and assemble it for evaluation. The main sources of information are the part print process sheets. Make sure that part documents and records are current. For example, verify that the shop print is the current revision, and the processing information is up-to-date. Check with the design department for pending part revisions. An important part of the evaluation process is note taking. Complete, accurate notes allow designers to record important information. With these notes, they should be able to fill in all items on the “Checklist for Design Considerations.” All ideas, thoughts, observations, and any other data about the part or fixture are then available for later reference. It is always better to have too many ideas about a particular design than too few. Four categories of design considerations need to be taken into account at this time: work piece specifications, operation variables, availability of equipment, and personnel. These categories, while separately covered here, are actually

Step 3: Develop Several Options

This phase of the fixture-design process requires the most creativity. A typical work-piece can be located and clamped several different ways. The natural tendency is to think of one solution, then develop and refine it while blocking out other, perhaps better solutions. A designer should brainstorm for several good tooling alternatives, not just choose one path right away. During this phase, the designer’s goal should be adding options, not discarding them. In the interest of economy, alternative designs should be developed only far enough to make sure they are feasible and to do a cost estimate. The designer usually starts with at least three options: permanent, modular, and general-purpose work holding. Each of these options has many clamping and locating options of its own.

— Page 15
The more standard locating and clamping. Devices that a designer is familiar with, the more creative he can be. Devices that a designer is familiar with, the more creative he can be. Areas for locating a part include flat exterior surfaces (machined and machined), cylindrical and curved exterior surfaces. The exact procedure used to construct the preliminary design sketches is not as important as the items sketched. Generally, the preliminary sketch should start should start with the part to be fixtured. The required locating and supporting elements, including a base, should be the next items added. Then sketch the clamping devices. Finally, add the machine tool and cutting tools. Sketching these items together helps identify any problem areas in the design of the complete fixture.

Step 4: Choose the Best Option

The total cost to manufacture a part is the sum of per-piece run cost, setup cost, and tooling cost. Expressed as a These variables are described below with sample values from three tooling options: a modular fixture, a permanent fixture, and a hydraulically powered permanent fixture.

Step 5: Implement the Design

The final phase of the fixture-design process consists of turning the chosen design approach into reality. Final details are decided, final drawings are made, and the tooling is built and tested. The following guidelines should be considered during the final-design process to make the fixture less costly while improving its efficiency. These rules are a mix of practical considerations, sound design practices, and common sense

(I)Use standard components:

The economies of standard parts apply to tooling components as well as to manufactured products. Standard, readily available components include clamps, locators, supports, studs, nuts, pins and a host of other elements. Most designers would never think of having the shop make cap screws, bolts or nuts for a fixture. Likewise, no standard tooling components should be made in-house. The first rule of economic design is: Never build any component you can buy. Commercially available tooling components are manufactured in large quantities for much greater economy. In most cases, the
Cost of buying a component is less than 20% of the cost of making it.

— Page 16
(II)Use prefinished materials:

Prefinished and preformed materials should be used where possible to lower costs and simplify construction. These materials include precision-ground flat stock, drill rod, structural sections, cast tooling sections, precast tooling bodies, tooling plates, and other standard preformed materials. Including these materials in a design both reduces the design time and lowers the labor cost.

(III)Eliminate finishing operations:

Finishing operations should never be performed for cosmetic purposes. Making a Fabrication fixture look better often can double its cost. Here are a few suggestions to keep in mind with regard to finishing operations.

The most cost-effective tooling tolerance for a locator is approximately 30% to 50% of the work piece’s tolerance. Tighter tolerances normally add extra cost to the tooling with little benefit to the process. Where necessary, tighter tolerances can be used, but tighter tolerances do not necessarily result in a better fixture, only a more expensive one.

2.2 MEANING OF LOCATION

The location refers to the establishment of a desired relationship between the work piece and the jigs or fixture correctness of location directly influences the accuracy of the finished product. To position the work piece w.r.t. to tool, to ensure precision in machining. Dimensional and positional relationship between work piece and tool device to establish and maintain position of a part in a jig or fixture.
The jigs and fixtures are desired so that all undesirable movements of the work piece can be restricted. Determination of the locating points and clamping of the work piece serve to restrict movements of the component in any direction, while setting it in a particular pre-decided position relative to the jig. Before deciding the locating points it is advisable to find out the all possible degrees of freedom of the work piece. Then some of the degrees of freedom or all of them are restrained by making suitable arrangements. These arrangements are called locators. These are described in details in location principle.
— Page 17
2.2.1 Six pin (3-2-1) locating principle

A work piece free in space can move in an infinite number of directions. For analysis, this motion can be broken down into twelve directional movements, or “degrees of freedom.” All twelve degrees of freedom must be restricted to ensure proper referencing of a work piece.

Fig. 2.1. 3-2-1 locating principle
As shown in Figure 2.02, the twelve degrees of freedom all relate to the central axes of the work piece. Notice the six axial degrees of freedom and six radial degrees of freedom. The axial degrees of freedom permit straight-line movement in both directions along the three principal axes, shown as x, y, and z. The radial degrees of freedom permit rotational movement, in both clockwise and counter clockwise radial directions, around the same three axes. The devices that restrict a work piece’s movement are the locators. The locators, therefore, must be strong enough to maintain the position of the work piece and to resist the cutting forces. This fact also points out a crucial element in work holder design: locators, not clamps, must hold the work piece against the cutting forces. Locators provide a positive stop for the work piece. Placed against the stop, the work piece cannot move. Clamps, on the other hand, rely only upon friction between the clamp and the clamped surface to hold the work piece. Sufficient force could move the work piece. Clamps are only intended to hold the work piece against the locators.

6 translational degrees of freedom: +X, -X, +Y, -Y, +Z, -Z

6 rotational degrees of freedom:

— Page 18

You must fix all the 12 degrees of freedom except the three transitional degrees of freedom (-X, -Y and -Z) in order to locate the work piece in the fixture. So, 9 degrees of freedom of the work piece need to be fixed by using the 3-2-1 method.

Fig 2.2 fixture set up-(3-2-1 on principle)

— Page 19

2.3 CLAMPING

Once work piece is located, it is necessary to press it against locating surfaces and hold it there against the force acting upon it. The tool designer refers to this action as clamping and the mechanisms used for this action are known as clamps.

‘ Clamp should firmly hold the work piece without distorting it.
‘ Should overcome the maximum possible force exerted on work piece by using minimum clamping force
‘ Easy to operate
‘ Vibrations should tighten the cams and wedges in the clamp design (if any) and not loosen them

Fig 2.3 position of holding work piece

2.4Fixturing Functional Requirements

1) Stable resting,

2) Accurate localization.

3) support reinforcement,

4) stable clamping,

5) fore closure(or total restraint) and

6) Quality performance.

— Page 20

The functions have strong precede the first five functions are required at the fixturing stage, and sequentially. When a work piece is placed into a fixture, it must first assume a stable resting against the gravity. Then, the locators should provide accurate localization. Next, supports are moved in place, and finally clamps are activated for the part immobilization (force-closure). The part location must be maintained in the process of instantiating clamps without work piece lift-off. The performance of the fixture is ultimately defined as work piece geometric error during the manufacturing stage. The geometric error is mainly determined by the fixture localization accuracy and the work piece static and elastic deformation during manufacturing. There are additional constraints to be satisfied such as interference-free and easy loading and unloading.

2.4.1 Design Consideration in Fixtures

The main frame of fixture must be strong enough so that deflection of the fixture is as minimum as possible. This deflection of fixture is caused because of forces of cutting, clamping of the work piece or clamping to the machine table. The main frame of the fixture should have the mass to prevent vibration and chatter.
‘ Frames may be built from simple sections so that frames may be fastened with screws or welded whenever necessary. Those parts of the frame that remain permanently with the fixture may be welded. Those parts that need frequent changing may be held with the screws.

‘ In the situation, where the body of fixture has complex shape, it may be cast from good grade of cast iron. All locator’s clamps should be easily visible to the operator. ‘

‘ Clamping should be fast enough and require least amount of effort.’

‘ Clamps should be arranged so that they are readily available and may be easily removed.’

‘ Clamps should be supported with springs so that clamps are held against the bolt head wherever possible.’
‘ Permitted to swing as far as it is necessary for removal of the work piece.

— Page 21


PROBLEM DEFINATION:-

From literature it have been found that there is not any arc welding flexible fixtures available. It is planned to Design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

— Page 22

3. DESIGN ASPECTS

3.1 Individual Design of flexible fixture parts

This section covered different aspects of design of arc welding fixture with cutting action.

3.1.1 Design of supporting frame

Frame is consist of uniform member (of circular section, angle section, channel section, square section etc.) joined together at their ends by riveting or welding.in case of our project welding fixture, we need a support structure of all other member like square slotted pate, clamping device and work piece plate which is required to welded.so it is easy to fabricate a square section plate frame by welding. So we select the frame as a hollow square cross section plate from Indian standard.
Selection of material for frame
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993) Fe 470 W Steel with a minimum tensile strength of 470 N/mm and of guaranteed fusion welding quality in real application of fe470 in clutch and free wheel clutch.

‘ Specification of frame material i.e. Fe 470
‘ Indian standard designation = Fe 470

‘ Tensile strength ( minimum) = 580 N/mm”

‘ Yield strength (minimum) = 430 N/mm”

‘ Minimum percentage elongation = 21

‘ Bending strength = 230 N/mm”

— Page – 23

Fig 3.1 Drawing of supporting frame

Now, assume that the frame is a simply supported beam carrying Uniform Distributed Load (U.D.L) as 10,000 Newton on 1300 mm length. A little consideration show that a frame is subjected to bending as well as static load. As shown in table no.1 various value of F.O.S. for various material based on Indian standard.

Material Steady load Live load Shock load

Cast iron 5 to 6 8 to 12 16 to 20

Wrought iron 4 7 10 to 15

Steel 5 8 12 to 16

Soft material and 6 9 15
alloys

Leather 9 12 15

Timber 7 10 to 15 20

Table no. 1 various value of F.O.S. for various material

— Page 24

1) Frame subjecting to Static Load

Now assume factor of safety (F.O.S) = 5 (select from table no.1 for steel) Static Load (W) = 8000 N (Design load for fixture)

Design stress (”) = Yield strength / F.O.S

= 430/5

= 86 N/mm”

As per market evaluation we found standard cross section (50*50) for hollow square pipe.it capable for fixture as per loading condition.

So Area of cross section (A) = Hollow Square pipe

= 50*50

= 5 mm thick platen

Let we know that static stress

” = W/A

86 = 8000 /A
A = 8000/86

= 93.02 mm”

But, A= B”= 93.02

B = 9.64 mm > 50 mm hence safe in static loading.

2) Frame subjecting to bending Load

We know that the bending equation is given by

M/I = ”/Y = E/R

Where M = Bending moment acting at the given section

” = Bending stress

I = Moment of inertia of cross section about the neutral axis

Y = Distance from the neutral axis

— Page – 25

E = Young Modulus of elasticity of material

R = Radius of curvature of the beam

From above equation

Bending ” = M/I *Y

=M/Z

Where Z = section modulus = I / Y

Now assume that frame is a simply supported beam and also we know that Bending Moment of simply supported beam with U.D.L.

M = WL” / 8 (Equation for simply supported beam with U.D.L.)

Where W = U.D.L. on frame = 8,000N

L = Length of span (Frame) = 1300 mm

Hence M = 8,000*(1300)” ” 8

= 1690000000N*m

Now section modulus of square cross section

Z= (B4 – H4) ” 6B

= (504 – 404) ” 6*50

= 12300 mm”

Also bending ” = M”Z

= 1690000000 ” 12300

= 137.75 N/mm”

So bending stress ” = 137.75 N/mm” > 245 N/mm” (design bending stress) Hence it is prove that frame is safe in bending.

Final dimension of supporting frame

— Page – 26
Hollow square pipe cross section= 50*50 and 5mm thickness

Length of frame (L) = 1300 mm

Width of frame (W) = 400 mm

3.1.2 Design of vertical column

A machine part subjected to an axial compressive force is called strut. A strut may be horizontal, inclined, or even vertical. But a Vertical strut is known as a column. It has been observed that when a column is subjected to a compressive load and is gradually increased, a stage will reach when the column will be subjected to ultimate load. Beyond this, the column will fail by crushing and the load will be known as crushing load.

It has also been experienced, that sometimes, a compression member does not fail entirely by crushing, but also by bending i.e. buckling. If the load is gradually increased, the column will reach a stage, when it will start buckling. The load at which the column tends to buckle is called buckling load, critical load or crippling load and the column is said to have developed an elastic instability.

‘ Selection of material for vertical column
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993)We select the steel material Fe 330 as used for locomotive carriages and car structures, screw stock and other general engineering purpose.

Specification of vertical column material i.e. Fe 330
‘ Indian standard designation = Fe 330
‘ Tensile strength (minimum) = 330 N/mm”

‘ Yield strength (minimum) = 200 N/mm”

‘ Minimum percentage elongation = 26

‘ Crushing stress =330 N/mm”

‘ Young’s modulus = 0.21 * 106 N/mm”

‘ Area of cross section = 70*70 and 500 mm length

— Page – 27

Fig.3.2 drawing of vertical column

In actual practice, there are number of end condition for column. But in case our project parts as vertical column is a both ends fixed type square column.

‘ Maximum Crippling load capacity of column

Now we calculate maximum crippling load or buckling load by Rankine’s formula for column

Wc r= (”c * A) ” {1 + a (L/K)}

Where, Wcr= Crippling load

”c= Crushing stress

A = Cross sectional area of column

= 70 * 70

= 4900 mm”

a = Rankine’s constant = ”c/ (”*E)

= 1” 4500 (for mild steel)

L= Equivalent length of the column

— Page – 28
= l/2 (both ends fixed)

= 500/2

= 250

K=Least radius of gyration

=0.289 B (for square cross section) = 0.289 * 70 =20.23

Now,

Wcr= (330* 4900) ” {1 + (1” 4500 ) (250/20.23) }

= 1495215.823 N

= 1495.21 KN

So Maximum Crippling load capacity of column = 1495.21 KN

3.1.3Design of slotted plate

‘ Selection of slotted plate material

As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993). We select the steel material Fe 410 as used for specially used for High-strength Steel Plate.
‘ Specification of slotted plate material i.e. Fe 410

‘ Indian standard designation = Fe 410

‘ Tensile strength ( minimum) = 360 N/mm”

‘ Yield strength (minimum) = 225 N/mm”

‘ Minimum percentage elongation = 27

Area of cross section = 20*20 with 10 mm slot throughout length i.e. 750 mm and another plate is 1250 mm length

— Page – 29

Fig.3.3 drawing of slotted plate 1250 mm length

Fig.3.4 drawing of slotted plate 750 mm length

Now a slotted plate is design on its static strength so we assume that Factor of Safety (F.O.S) = 5 (select from table no.1 for steel)

”t = Tensile strength / F.O.S

= 360 / 5

= 72 N/mm2

— Page – 30
Also we know that ”t= W / A

72 = 8,000 / A
A = 8,000/ 72

= 111.11mm” But, A = B”

235.29= B”

B= 10.54 ~ 12 mm

Hence it is prove that frame is safe in static loading.

3.1.4 Design of shaft

A shaft is a rotating machine element which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and the resultant torque (or twisting moment) set up within the shaft permits the power to be transferred to various machines linked up to the shaft.

‘ Selection of shaft material

The material used for ordinary shaft is carbon steel of grades 40 C 8, 45 C 8, 50 C 4, 50 C 12. When a shaft of high strength is required, then an alloy steel such as nickel, nickel-chromium or chrome-vanadium steel is used. But as per our requirement is medium strength is needed, so we select ordinary steel of grade 50 C 4.

‘ Specification of shaft material i.e. 50 C 4.

‘ Indian standard designation = 50 C 4

‘ Ultimate tensile strength = 1080 N/mm”

‘ Yield strength =930 N/mm”

‘ Permissible tensile stress = 0.6”u

= 0.6 * 1080

— Page – 31

= 648 N/mm2

Permissible shear stress = 0.18”u

=0.18* 1080

= 194.4 N/mm2

As per market evaluation we found standard diameter (30 mm) for shaft. It capable for supporting frame as per loading condition.

Cross section of shaft = 30 mm diameter

= 100 mm length

A little consideration we show that in our project shaft is subjecting only twisting moment hence we design the shaft on the pure twisting moment equation.

Fig. 3.5 drawing of shaft

Maximum torque capacity of shaft

T = ” / 16 *”*d3

=” / 16*194.4*(30)3

= 1030599.47Nm

=1030.59 KNm

Hence Maximum torque capacity of shaft = 1030.59 KNm

— Page – 32

3.1.5 Design of Circular Indexing plate and Indexing pin

Main objective of indexing plate in flexible fixture is to rotate the frame at various angle i.e. Up to 180 degree of rotation and also fixed at a desired angle as per requirement of welder. A handle is provided on circular indexing plate it provide rotating movement of frame. By using an indexing pin (circular pin) frame can be fixed at required position. A hole provided on circumference of circular plate at regular interval i.e. (180/7) approximate 25 degree of each hole.by means of indexing pin attached in a Hole frame can be fixed as per requirement.

Fig. 3.6 drawing of circular indexing plate

— Page – 33

Fig.3.7 drawing of indexing pin

3.1.6 Design of clamping device and pin locator

‘ Make or buy decision for clamping device and pin locator

In case in fixture it’s required to fixed the work piece on the frame of fixture. This objective is done by using clamps and locating pin. In flexible fixture work piece i.e. plate are fixed by four clamping device and pin locator. But problems is that if clamps are make or buy from market.

If we make i.e. produced clamp in work shop so it is costly because we not produced in mass production. As well as it’s difficult to give accurate size of clamps. Also full facility of machining, casting and super finishing is not available in our work shop. As discussed above difficulty in making clamp and locating pin we purchase the required clamps and locating pin from market.

Fig.3.8 drawing of pin locator

— Page – 34

Fig.3.9 drawing of clamping device

— Page – 35

3.1.7 Summary of part design

As discussed above various parts of arc welding fixture as summarized in table no.2.

Sr. No. Name of Dimension No. of parts Material
part
1 Supporting L=1300 mm 1 Fe 470
frame W=400 mm
2 Vertical L = 500 mm 2 Fe 330
column 50*50square
cross section
3 Slotted plate 1 L= 1250 mm 2 Fe 410
4 Slotted plate 2 L= 750 mm 3 Fe 410
5 Shaft L= 100 mm 2 50 C4
D = 15 mm
6 Indexing plate D = 400 mm 1 Fe 290
t = 10 mm
with 7 hole
7 Clamp – 4 –
8 Locating pin – 4 –
Table no. 2 summary of parts for arc welding fixture

— Page – 36
3.2 Assembly of welding flexible fixture.

After all discussed above parts assemble and fabricate arc welding flexible fixture as shown fig. no 3.10

Fig.3.10 2D drawing of welding flexible fixture assembly

— Page – 37

Fig.3.11 3D drawing of welding flexible fixture assembly

— Page – 38

4. RESULTS AND CONCLUSION

Manufacture accurately interchangeable parts. Fixtures are specially designed so that large numbers of components can assembled identically, and to ensure interchangeability of components.

Facilitate economical production of engineering components.

The main functions of a welding fixture are:

Griping
A work piece in the predetermined manner of firmness and location.

Holding

Components rigid and prevent movement during welding in order to impart greater productivity and part accuracy.

Supporting and locating
Every component (part) to ensure that teach is welded within the specified limits.

Positioning

Components accurately and maintain relationship and alignment between the holder and the work piece correctly to perform on the work piece a welding operation.

Results:-

‘ welding with the help of arc welding fixtures reduced time for production of the component and also reduce the fatigue effect on worker due to ergonomically convenient for the operation

‘ with help of fixture effective clamping is done more accurate than the conventional method.

‘ the circular indexing plate gives rotational movement for the front side, topside weld more easier than the conventional method in which worker have to move the work piece as per the weld position.

— Page 39

‘ the hand cutter provide the facility to cut the frame or bar while the work piece clamped on the fixture

‘ in conventional method first worker to arrange accurately before weld of frame while in fixture with help of locator work piece automatically locating

‘ this fixtures increases the productivity, accuracy, reliability

Futures scope:-

In the above arc welding flexible fixtures various futures scope are as under

‘ Provide power driven or automatic movement of the circular indexing plate which reduces the worker fatigue.
‘ Here we only indexing up to the180 degree while with help of other clamping arrangement 360 degree indexing possible.
‘ The clamping surface are of the flat which only locate the flat work piece for provide V-shape at the end also possible for the circular work piece.
‘ To provide the scale on the slotted plate we adjust the clamp as per work piece size

— Page 40

5. REFERENCES:

Research paper:

‘ Design of Fixtures: A Review By Nisarg Parmar IJARIIE-ISSN(O)-2395-4396
http://www.ijariie.com
‘ A Review on Design of Fixtures by Shailesh S.Pachbhai & Laukik P.Raut International Journal of Engineering Research and General Science Volume 2, Issue 2, Feb-Mar 2014 ISSN 2091-2730
‘ Design of Welding Fixtures and Positiners
Prof. S.N.Shinde, Siddharth Kshirsagar, Aniruddha Patil, Tejas Parge, Ritesh Lomte
International Journal of Engineering Research and General Science Volume 2, Issue 5, August-September, 2014 ISSN 2091-2730

Books:

1) Text book of Machine Design by r.s khurmi and j.k gupta s chand publication

2) Text book of Production technology by r.k.jain Khanna publication

3) Production technology by p.c sharma s chand publication

4) Machine Tool Design by N. K. Mehta

— Page 41

A
PROJECT REPORT

ON

‘Design and manufacturing of flexible fixture for different frame welding’

Submitted by
1) Gurjar Jignesh (130210119047)
2) Zala Pushparajsinh (130210119125)
3) Katariya Piyush (140213119014)
4) Radhanpura Nadim (140213119021)

In fulfilment for the award of the degree

Of

BACHELOR OF ENGINEERING

In
Mechanical engineering

Government Engineering Collage, Bhavnagar
Gujarat Technology University, Ahmedabad

— Page 1

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Gurjar Jigneshkumar Maganbhai under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Radhanpura Nadim under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Zala Pushparajsinh, under my guidance in fulfilment of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

Government Engineering Collage, Bhavnagar

Mechanical Engineering 2016

CERTIFICATE

Date:

This is to certify that the dissertation entitled ‘Design And
Manufacturing of Flexible Fixture for Different Frame Welding’
Has been carried out by Katariya Piyush, under my guidance in fulfilment
Of the degree of Bachelor of Engineering in Mechanical Engineering (7th semester) of Gujarat Technology University, Ahmedabad during the academic year 2016-2017

Project Guide: Head of Department:
Prof. N.K.Tank
Prof. (Dr). J.M.Patel

— Page 2

ABSTRACT

In modern industrial work number of various material in different shape and size are required to develop various component for different application. Welding is one of the important fabrication process in product development work. Development of flexible fixtures for welding process is today’s requirement is reduce operation time, increase production and high quality of production.

It is planned to design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

Key words: – Welding, Flexible Fixture.

— Page 3

ACKNOWLEDGEMENT

I am using this opportunity to express my gratitude to everyone who supported me throughout the course of this final year project. I am thankful for their aspiring guidance, invaluably constructive criticism and friendly advice during the project work. I am sincerely grateful to them for sharing their truthful and illuminating views on a number of issues related to the project.

I express my warm thanks to Prof. N.K Tank for their support and excellent guidance from starting to the end of our final year project at Government Engineering Collage, Bhavnagar. Also thankful to the Mechanical Department for their active cooperation and support whose encouragement, continuous guidance, helpful nature, new suggestion and ideas were invaluable for accomplishment of this work.

Thank you

Gurjar Jignesh

Zala Pushparajsinh

Katariya Piyush

Radhanpura Nadim

— Page 4

LIST OF TABLES

Table No. Table Description Page No.
Table no.1 various value of F.O.S. for various material 24
Table no.2 Summary of part design 36

— PAGE 5

LIST OF FIGURES

Figure No. Figure Description Page No.
Fig 1.1 (a) Jig (B) Fixture 10
Fig 1.2 Manual metal arc welding process 11
Fig 2.1 Principle of fixture (3-2-1) 18
Fig 2.2 Fixture set up-(3-2-1 on principle) 19
Fig 2.3 Holding work piece position 20
Fig 3.1 Drawing of supporting frame 24
Fig 3.2 Drawing of vertical column 28
Fig 3.3 Drawing of slotted plate 1250 mm 30
Fig 3.4 Drawing of slotted plate 750 mm 32
Fig 3.5 Drawing of shaft 33
Fig 3.6 Drawing of circular indexing plate 34
Fig 3.7 Drawing of indexing pin 35

— Page 6

Figure No. Figure Description Page No.
Fig 3.8 Drawing of Pin locator 35
Fig 3.9 Drawing of Clamping device 35
Fig 3.10 2D drawing of welding flexible fixture assembly 37
Fig 3.11 3D drawing of welding flexible fixture assembly 38

— Page 7

TABLE OF CONTENTS

Sr.no TITLE PAGE NO.
1 Abstract 3
2 Acknowledgement 4
3 List of Tables 5
4 List of Figures 6
INTRODUCTION 10
1.1 Jig and fixture
1.2 Fixture for arc welding process
a) Role of fixture in arc welding process
b) Advantages of fixture used in arc welding process
1.3 Fundamental principles of Arc weld Fixtures design
LITERATURE REVIEW 14
2.1 Steps of Fabrication fixture design
2.2 Location- Six pin (3-2-1) locating principle
2.3 Clamping
2.4 Fixturing Functional Requirements

— R Page 8
Sr.no DESIGN ASPECTS 23

3.1 Individual design of arc welding fixture
3.1.1 Design of supporting frame
3.1.2 Design of vertical column
3.1.3 Design of slotted plate
3.1.4 Design of shaft
3.1.5 Design of circular indexing plate and pin
3.1.6 Design of clamping device
3.1.7 Summary of part design
3.2 drawing and 3-D model of assembly

4. RESULTS & CONCLUSION 39

5. REFERENCES 41

— Page 9

1. INTRODUCTION

1.1 Jigs and fixture:-

The fixture is a special tool for holding a work piece in proper position during manufacturing operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in manufacturing process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages. To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators.

Jig: is a fixture with an additional feature of tool guidance

Fixture: fixture, being used in machine shop, are strong and rigid mechanical devices which enable easy, quick and consistently accurate locating. Supporting and clamping, blanks against cutting tools and result faster and accurate machining with consistent quality, functional ability and interchangeability.

(A) Jig (B) Fixture

Fig. 1.1

— Page 10
1.2 Fixture in arc welding process:-

As the manufacturing costs of the metal-working industry are nowadays mainly determined by the costs of labor with accuracy, many industries are compelled to rationalize their manufacturing methods by partially and fully mechanized production processes. In the field of welding engineering where a consistently excellent quality with an optimum productivity is a must, automation aspects are consequently taken into account.

Fig.1.2 Manual metal arc welding process (MMAW)

Figure shows manual metal arc welding (MMAW), in this case manual electrode welding. The control of the electrode and/or the arc is carried out manually. The filler metal (the consumable electrode) is also fed manually to the welding point.
a) Role of flexible fixture in arc welding processes:-

‘ Hold the parts in correct position.’
‘ Assist and control the joining process.”
‘ Mechanically or Alignment of work pieces
o ‘
‘ Tooling for hot processes should withstand heat and accelerate or retard flow of heat’Hot fixtures should have thermal expansion coefficient so that it remains functional.

— Page 11
Advantages of fixture used in arc welding processes:-


‘ To assure high accuracy of welding parts.’

‘ Provide for interchangeability in assembly.

‘ Enable heavy and complex parts to be weld.’

‘ Reduce distortion.

‘ Saving in labor time and less kills require.’

‘ Use improve the safety and reduced accidents.’

‘ Produce Interchangeable and Quality parts
‘ Reduction cost of manufacturing”

1.3 Fundamental principles of Arc weld flexible Fixtures design:-

a) Locating points: Good facilities should be provided for locating the work. The article to be machined must be easily inserted and quickly taken out from the fixture so that no time is wasted in placing the work piece in position to perform operations. The position of work piece should be accurate with respect to tool guiding in the jig or setting elements in fixture.

b) fool proof: It can be defined as ‘the incorporation of design feature in the fixture that will make it possible to lead the work into fixture, in an improper position but will not interface with loading and unloading the work piece” there are many fool proofing device, such as fooling pegs, blocks or pins which clear correctly position parts but prevent incorrectly loaded parts from entering the fixture body.
c) Simplicity surface: machining on the work piece must be clearly visible to the worker. He should not be required to bend is neck for seeing the work piece or work surface.
d) Weight of weld fixtures: It should be easy to handle smaller in size and low cost in regard to amount of material used without sacrificing rigidity and stiffness.

— Page 12

e) Materials for jigs and fixtures: Usually made of hardened materials to avoid frequent damage and to resist wear.

Example- MS, Cast iron, Die steel, CS, HSS.

f) Clamping device: It should be as simple as possible without sacrificing effectiveness. The strength of clamp should be such that not only to hold the work piece firmly in place but also to take the Thermal stresses produced during welding, when designing the weld fixtures.

— Page 13
2. LITERATURE REVIEW

The fixture is a special tool for holding a work piece in proper position during Fabrication operation. For supporting and clamping the work piece, device is provided. Frequent checking, positioning, individual marking and non-uniform quality in Fabrication process is eliminated by fixture. This increase productivity and reduce operation time. Fixture is widely used in the industry practical production because of feature and advantages.

To locate and immobilize work pieces for machining, inspection, assembly and other operations fixtures are used. A fixture consists of a set of locators and clamps. Locators are used to determine the position and orientation of a work piece, whereas clamps exert clamping forces so that the work piece is pressed firmly against locators. Clamping has to be appropriately planned at the stage of machining fixture design. The design of a fixture is a highly complex and intuitive process, which require knowledge. Fabrication Fixture design plays an important role at the setup planning phase. Proper fixture design is crucial for developing product quality in different terms of accuracy, surface finish and precision of the machined parts in existing design the Fabrication fixture set up is done manually, so the aim of this project is to replace with Fabrication fixture to save time for loading and unloading of component. Fabrication fixture provides the manufacturer for flexibility in holding forces and to optimize design for Fabrication operation as well as process function ability.

2.1 Steps of Fabrication fixture design

Successful fixture designs begin with a logical and systematic plan. With a complete analysis of the

Fixture’s functional requirements, very few design problems occur. When they do, chances are some

Design requirements were forgotten or underestimated. The work piece, processing, tooling and

Available machine tools may affect the extent of planning needed. Preliminary analysis may take from

Few hours up to several days for more complicated fixture designs. Fixture design is a five-step

Problem-solving process. The following is a detailed analysis of each step.

— Page 14
Step 1: Define Requirements

To initiate the Fabrication fixture-design process, clearly state the problem to be solved or needs to be met. State these requirements as broadly as possible, but specifically enough to define the scope of the design project. The designer should ask some basic questions: Is the new tooling required for first-time production or to improve existing production

Step 2: Gather/Analyze Information

Collect all relevant data and assemble it for evaluation. The main sources of information are the part print process sheets. Make sure that part documents and records are current. For example, verify that the shop print is the current revision, and the processing information is up-to-date. Check with the design department for pending part revisions. An important part of the evaluation process is note taking. Complete, accurate notes allow designers to record important information. With these notes, they should be able to fill in all items on the “Checklist for Design Considerations.” All ideas, thoughts, observations, and any other data about the part or fixture are then available for later reference. It is always better to have too many ideas about a particular design than too few. Four categories of design considerations need to be taken into account at this time: work piece specifications, operation variables, availability of equipment, and personnel. These categories, while separately covered here, are actually

Step 3: Develop Several Options

This phase of the fixture-design process requires the most creativity. A typical work-piece can be located and clamped several different ways. The natural tendency is to think of one solution, then develop and refine it while blocking out other, perhaps better solutions. A designer should brainstorm for several good tooling alternatives, not just choose one path right away. During this phase, the designer’s goal should be adding options, not discarding them. In the interest of economy, alternative designs should be developed only far enough to make sure they are feasible and to do a cost estimate. The designer usually starts with at least three options: permanent, modular, and general-purpose work holding. Each of these options has many clamping and locating options of its own.

— Page 15
The more standard locating and clamping. Devices that a designer is familiar with, the more creative he can be. Devices that a designer is familiar with, the more creative he can be. Areas for locating a part include flat exterior surfaces (machined and machined), cylindrical and curved exterior surfaces. The exact procedure used to construct the preliminary design sketches is not as important as the items sketched. Generally, the preliminary sketch should start should start with the part to be fixtured. The required locating and supporting elements, including a base, should be the next items added. Then sketch the clamping devices. Finally, add the machine tool and cutting tools. Sketching these items together helps identify any problem areas in the design of the complete fixture.

Step 4: Choose the Best Option

The total cost to manufacture a part is the sum of per-piece run cost, setup cost, and tooling cost. Expressed as a These variables are described below with sample values from three tooling options: a modular fixture, a permanent fixture, and a hydraulically powered permanent fixture.

Step 5: Implement the Design

The final phase of the fixture-design process consists of turning the chosen design approach into reality. Final details are decided, final drawings are made, and the tooling is built and tested. The following guidelines should be considered during the final-design process to make the fixture less costly while improving its efficiency. These rules are a mix of practical considerations, sound design practices, and common sense

(I)Use standard components:

The economies of standard parts apply to tooling components as well as to manufactured products. Standard, readily available components include clamps, locators, supports, studs, nuts, pins and a host of other elements. Most designers would never think of having the shop make cap screws, bolts or nuts for a fixture. Likewise, no standard tooling components should be made in-house. The first rule of economic design is: Never build any component you can buy. Commercially available tooling components are manufactured in large quantities for much greater economy. In most cases, the
Cost of buying a component is less than 20% of the cost of making it.

— Page 16
(II)Use prefinished materials:

Prefinished and preformed materials should be used where possible to lower costs and simplify construction. These materials include precision-ground flat stock, drill rod, structural sections, cast tooling sections, precast tooling bodies, tooling plates, and other standard preformed materials. Including these materials in a design both reduces the design time and lowers the labor cost.

(III)Eliminate finishing operations:

Finishing operations should never be performed for cosmetic purposes. Making a Fabrication fixture look better often can double its cost. Here are a few suggestions to keep in mind with regard to finishing operations.

The most cost-effective tooling tolerance for a locator is approximately 30% to 50% of the work piece’s tolerance. Tighter tolerances normally add extra cost to the tooling with little benefit to the process. Where necessary, tighter tolerances can be used, but tighter tolerances do not necessarily result in a better fixture, only a more expensive one.

2.2 MEANING OF LOCATION

The location refers to the establishment of a desired relationship between the work piece and the jigs or fixture correctness of location directly influences the accuracy of the finished product. To position the work piece w.r.t. to tool, to ensure precision in machining. Dimensional and positional relationship between work piece and tool device to establish and maintain position of a part in a jig or fixture.
The jigs and fixtures are desired so that all undesirable movements of the work piece can be restricted. Determination of the locating points and clamping of the work piece serve to restrict movements of the component in any direction, while setting it in a particular pre-decided position relative to the jig. Before deciding the locating points it is advisable to find out the all possible degrees of freedom of the work piece. Then some of the degrees of freedom or all of them are restrained by making suitable arrangements. These arrangements are called locators. These are described in details in location principle.
— Page 17
2.2.1 Six pin (3-2-1) locating principle

A work piece free in space can move in an infinite number of directions. For analysis, this motion can be broken down into twelve directional movements, or “degrees of freedom.” All twelve degrees of freedom must be restricted to ensure proper referencing of a work piece.

Fig. 2.1. 3-2-1 locating principle
As shown in Figure 2.02, the twelve degrees of freedom all relate to the central axes of the work piece. Notice the six axial degrees of freedom and six radial degrees of freedom. The axial degrees of freedom permit straight-line movement in both directions along the three principal axes, shown as x, y, and z. The radial degrees of freedom permit rotational movement, in both clockwise and counter clockwise radial directions, around the same three axes. The devices that restrict a work piece’s movement are the locators. The locators, therefore, must be strong enough to maintain the position of the work piece and to resist the cutting forces. This fact also points out a crucial element in work holder design: locators, not clamps, must hold the work piece against the cutting forces. Locators provide a positive stop for the work piece. Placed against the stop, the work piece cannot move. Clamps, on the other hand, rely only upon friction between the clamp and the clamped surface to hold the work piece. Sufficient force could move the work piece. Clamps are only intended to hold the work piece against the locators.

6 translational degrees of freedom: +X, -X, +Y, -Y, +Z, -Z

6 rotational degrees of freedom:

— Page 18

You must fix all the 12 degrees of freedom except the three transitional degrees of freedom (-X, -Y and -Z) in order to locate the work piece in the fixture. So, 9 degrees of freedom of the work piece need to be fixed by using the 3-2-1 method.

Fig 2.2 fixture set up-(3-2-1 on principle)

— Page 19

2.3 CLAMPING

Once work piece is located, it is necessary to press it against locating surfaces and hold it there against the force acting upon it. The tool designer refers to this action as clamping and the mechanisms used for this action are known as clamps.

‘ Clamp should firmly hold the work piece without distorting it.
‘ Should overcome the maximum possible force exerted on work piece by using minimum clamping force
‘ Easy to operate
‘ Vibrations should tighten the cams and wedges in the clamp design (if any) and not loosen them

Fig 2.3 position of holding work piece

2.4Fixturing Functional Requirements

1) Stable resting,

2) Accurate localization.

3) support reinforcement,

4) stable clamping,

5) fore closure(or total restraint) and

6) Quality performance.

— Page 20

The functions have strong precede the first five functions are required at the fixturing stage, and sequentially. When a work piece is placed into a fixture, it must first assume a stable resting against the gravity. Then, the locators should provide accurate localization. Next, supports are moved in place, and finally clamps are activated for the part immobilization (force-closure). The part location must be maintained in the process of instantiating clamps without work piece lift-off. The performance of the fixture is ultimately defined as work piece geometric error during the manufacturing stage. The geometric error is mainly determined by the fixture localization accuracy and the work piece static and elastic deformation during manufacturing. There are additional constraints to be satisfied such as interference-free and easy loading and unloading.

2.4.1 Design Consideration in Fixtures

The main frame of fixture must be strong enough so that deflection of the fixture is as minimum as possible. This deflection of fixture is caused because of forces of cutting, clamping of the work piece or clamping to the machine table. The main frame of the fixture should have the mass to prevent vibration and chatter.
‘ Frames may be built from simple sections so that frames may be fastened with screws or welded whenever necessary. Those parts of the frame that remain permanently with the fixture may be welded. Those parts that need frequent changing may be held with the screws.

‘ In the situation, where the body of fixture has complex shape, it may be cast from good grade of cast iron. All locator’s clamps should be easily visible to the operator. ‘

‘ Clamping should be fast enough and require least amount of effort.’

‘ Clamps should be arranged so that they are readily available and may be easily removed.’

‘ Clamps should be supported with springs so that clamps are held against the bolt head wherever possible.’
‘ Permitted to swing as far as it is necessary for removal of the work piece.

— Page 21


PROBLEM DEFINATION:-

From literature it have been found that there is not any arc welding flexible fixtures available. It is planned to Design and manufacturing of flexible fixture for different frame welding to perform the work at single stage. Due to this reduce overall man power work as well as time.

— Page 22

3. DESIGN ASPECTS

3.1 Individual Design of flexible fixture parts

This section covered different aspects of design of arc welding fixture with cutting action.

3.1.1 Design of supporting frame

Frame is consist of uniform member (of circular section, angle section, channel section, square section etc.) joined together at their ends by riveting or welding.in case of our project welding fixture, we need a support structure of all other member like square slotted pate, clamping device and work piece plate which is required to welded.so it is easy to fabricate a square section plate frame by welding. So we select the frame as a hollow square cross section plate from Indian standard.
Selection of material for frame
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993) Fe 470 W Steel with a minimum tensile strength of 470 N/mm and of guaranteed fusion welding quality in real application of fe470 in clutch and free wheel clutch.

‘ Specification of frame material i.e. Fe 470
‘ Indian standard designation = Fe 470

‘ Tensile strength ( minimum) = 580 N/mm”

‘ Yield strength (minimum) = 430 N/mm”

‘ Minimum percentage elongation = 21

‘ Bending strength = 230 N/mm”

— Page – 23

Fig 3.1 Drawing of supporting frame

Now, assume that the frame is a simply supported beam carrying Uniform Distributed Load (U.D.L) as 10,000 Newton on 1300 mm length. A little consideration show that a frame is subjected to bending as well as static load. As shown in table no.1 various value of F.O.S. for various material based on Indian standard.

Material Steady load Live load Shock load

Cast iron 5 to 6 8 to 12 16 to 20

Wrought iron 4 7 10 to 15

Steel 5 8 12 to 16

Soft material and 6 9 15
alloys

Leather 9 12 15

Timber 7 10 to 15 20

Table no. 1 various value of F.O.S. for various material

— Page 24

1) Frame subjecting to Static Load

Now assume factor of safety (F.O.S) = 5 (select from table no.1 for steel) Static Load (W) = 8000 N (Design load for fixture)

Design stress (”) = Yield strength / F.O.S

= 430/5

= 86 N/mm”

As per market evaluation we found standard cross section (50*50) for hollow square pipe.it capable for fixture as per loading condition.

So Area of cross section (A) = Hollow Square pipe

= 50*50

= 5 mm thick platen

Let we know that static stress

” = W/A

86 = 8000 /A
A = 8000/86

= 93.02 mm”

But, A= B”= 93.02

B = 9.64 mm > 50 mm hence safe in static loading.

2) Frame subjecting to bending Load

We know that the bending equation is given by

M/I = ”/Y = E/R

Where M = Bending moment acting at the given section

” = Bending stress

I = Moment of inertia of cross section about the neutral axis

Y = Distance from the neutral axis

— Page – 25

E = Young Modulus of elasticity of material

R = Radius of curvature of the beam

From above equation

Bending ” = M/I *Y

=M/Z

Where Z = section modulus = I / Y

Now assume that frame is a simply supported beam and also we know that Bending Moment of simply supported beam with U.D.L.

M = WL” / 8 (Equation for simply supported beam with U.D.L.)

Where W = U.D.L. on frame = 8,000N

L = Length of span (Frame) = 1300 mm

Hence M = 8,000*(1300)” ” 8

= 1690000000N*m

Now section modulus of square cross section

Z= (B4 – H4) ” 6B

= (504 – 404) ” 6*50

= 12300 mm”

Also bending ” = M”Z

= 1690000000 ” 12300

= 137.75 N/mm”

So bending stress ” = 137.75 N/mm” > 245 N/mm” (design bending stress) Hence it is prove that frame is safe in bending.

Final dimension of supporting frame

— Page – 26
Hollow square pipe cross section= 50*50 and 5mm thickness

Length of frame (L) = 1300 mm

Width of frame (W) = 400 mm

3.1.2 Design of vertical column

A machine part subjected to an axial compressive force is called strut. A strut may be horizontal, inclined, or even vertical. But a Vertical strut is known as a column. It has been observed that when a column is subjected to a compressive load and is gradually increased, a stage will reach when the column will be subjected to ultimate load. Beyond this, the column will fail by crushing and the load will be known as crushing load.

It has also been experienced, that sometimes, a compression member does not fail entirely by crushing, but also by bending i.e. buckling. If the load is gradually increased, the column will reach a stage, when it will start buckling. The load at which the column tends to buckle is called buckling load, critical load or crippling load and the column is said to have developed an elastic instability.

‘ Selection of material for vertical column
As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993)We select the steel material Fe 330 as used for locomotive carriages and car structures, screw stock and other general engineering purpose.

Specification of vertical column material i.e. Fe 330
‘ Indian standard designation = Fe 330
‘ Tensile strength (minimum) = 330 N/mm”

‘ Yield strength (minimum) = 200 N/mm”

‘ Minimum percentage elongation = 26

‘ Crushing stress =330 N/mm”

‘ Young’s modulus = 0.21 * 106 N/mm”

‘ Area of cross section = 70*70 and 500 mm length

— Page – 27

Fig.3.2 drawing of vertical column

In actual practice, there are number of end condition for column. But in case our project parts as vertical column is a both ends fixed type square column.

‘ Maximum Crippling load capacity of column

Now we calculate maximum crippling load or buckling load by Rankine’s formula for column

Wc r= (”c * A) ” {1 + a (L/K)}

Where, Wcr= Crippling load

”c= Crushing stress

A = Cross sectional area of column

= 70 * 70

= 4900 mm”

a = Rankine’s constant = ”c/ (”*E)

= 1” 4500 (for mild steel)

L= Equivalent length of the column

— Page – 28
= l/2 (both ends fixed)

= 500/2

= 250

K=Least radius of gyration

=0.289 B (for square cross section) = 0.289 * 70 =20.23

Now,

Wcr= (330* 4900) ” {1 + (1” 4500 ) (250/20.23) }

= 1495215.823 N

= 1495.21 KN

So Maximum Crippling load capacity of column = 1495.21 KN

3.1.3Design of slotted plate

‘ Selection of slotted plate material

As per Indian standard designation of steel according to IS: 1570 (part-I) ‘ 1978 (Reaffirmed 1993). We select the steel material Fe 410 as used for specially used for High-strength Steel Plate.
‘ Specification of slotted plate material i.e. Fe 410

‘ Indian standard designation = Fe 410

‘ Tensile strength ( minimum) = 360 N/mm”

‘ Yield strength (minimum) = 225 N/mm”

‘ Minimum percentage elongation = 27

Area of cross section = 20*20 with 10 mm slot throughout length i.e. 750 mm and another plate is 1250 mm length

— Page – 29

Fig.3.3 drawing of slotted plate 1250 mm length

Fig.3.4 drawing of slotted plate 750 mm length

Now a slotted plate is design on its static strength so we assume that Factor of Safety (F.O.S) = 5 (select from table no.1 for steel)

”t = Tensile strength / F.O.S

= 360 / 5

= 72 N/mm2

— Page – 30
Also we know that ”t= W / A

72 = 8,000 / A
A = 8,000/ 72

= 111.11mm” But, A = B”

235.29= B”

B= 10.54 ~ 12 mm

Hence it is prove that frame is safe in static loading.

3.1.4 Design of shaft

A shaft is a rotating machine element which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and the resultant torque (or twisting moment) set up within the shaft permits the power to be transferred to various machines linked up to the shaft.

‘ Selection of shaft material

The material used for ordinary shaft is carbon steel of grades 40 C 8, 45 C 8, 50 C 4, 50 C 12. When a shaft of high strength is required, then an alloy steel such as nickel, nickel-chromium or chrome-vanadium steel is used. But as per our requirement is medium strength is needed, so we select ordinary steel of grade 50 C 4.

‘ Specification of shaft material i.e. 50 C 4.

‘ Indian standard designation = 50 C 4

‘ Ultimate tensile strength = 1080 N/mm”

‘ Yield strength =930 N/mm”

‘ Permissible tensile stress = 0.6”u

= 0.6 * 1080

— Page – 31

= 648 N/mm2

Permissible shear stress = 0.18”u

=0.18* 1080

= 194.4 N/mm2

As per market evaluation we found standard diameter (30 mm) for shaft. It capable for supporting frame as per loading condition.

Cross section of shaft = 30 mm diameter

= 100 mm length

A little consideration we show that in our project shaft is subjecting only twisting moment hence we design the shaft on the pure twisting moment equation.

Fig. 3.5 drawing of shaft

Maximum torque capacity of shaft

T = ” / 16 *”*d3

=” / 16*194.4*(30)3

= 1030599.47Nm

=1030.59 KNm

Hence Maximum torque capacity of shaft = 1030.59 KNm

— Page – 32

3.1.5 Design of Circular Indexing plate and Indexing pin

Main objective of indexing plate in flexible fixture is to rotate the frame at various angle i.e. Up to 180 degree of rotation and also fixed at a desired angle as per requirement of welder. A handle is provided on circular indexing plate it provide rotating movement of frame. By using an indexing pin (circular pin) frame can be fixed at required position. A hole provided on circumference of circular plate at regular interval i.e. (180/7) approximate 25 degree of each hole.by means of indexing pin attached in a Hole frame can be fixed as per requirement.

Fig. 3.6 drawing of circular indexing plate

— Page – 33

Fig.3.7 drawing of indexing pin

3.1.6 Design of clamping device and pin locator

‘ Make or buy decision for clamping device and pin locator

In case in fixture it’s required to fixed the work piece on the frame of fixture. This objective is done by using clamps and locating pin. In flexible fixture work piece i.e. plate are fixed by four clamping device and pin locator. But problems is that if clamps are make or buy from market.

If we make i.e. produced clamp in work shop so it is costly because we not produced in mass production. As well as it’s difficult to give accurate size of clamps. Also full facility of machining, casting and super finishing is not available in our work shop. As discussed above difficulty in making clamp and locating pin we purchase the required clamps and locating pin from market.

Fig.3.8 drawing of pin locator

— Page – 34

Fig.3.9 drawing of clamping device

— Page – 35

3.1.7 Summary of part design

As discussed above various parts of arc welding fixture as summarized in table no.2.

Sr. No. Name of Dimension No. of parts Material
part
1 Supporting L=1300 mm 1 Fe 470
frame W=400 mm
2 Vertical L = 500 mm 2 Fe 330
column 50*50square
cross section
3 Slotted plate 1 L= 1250 mm 2 Fe 410
4 Slotted plate 2 L= 750 mm 3 Fe 410
5 Shaft L= 100 mm 2 50 C4
D = 15 mm
6 Indexing plate D = 400 mm 1 Fe 290
t = 10 mm
with 7 hole
7 Clamp – 4 –
8 Locating pin – 4 –
Table no. 2 summary of parts for arc welding fixture

— Page – 36
3.2 Assembly of welding flexible fixture.

After all discussed above parts assemble and fabricate arc welding flexible fixture as shown fig. no 3.10

Fig.3.10 2D drawing of welding flexible fixture assembly

— Page – 37

Fig.3.11 3D drawing of welding flexible fixture assembly

— Page – 38

4. RESULTS AND CONCLUSION

Manufacture accurately interchangeable parts. Fixtures are specially designed so that large numbers of components can assembled identically, and to ensure interchangeability of components.

Facilitate economical production of engineering components.

The main functions of a welding fixture are:

Griping
A work piece in the predetermined manner of firmness and location.

Holding

Components rigid and prevent movement during welding in order to impart greater productivity and part accuracy.

Supporting and locating
Every component (part) to ensure that teach is welded within the specified limits.

Positioning

Components accurately and maintain relationship and alignment between the holder and the work piece correctly to perform on the work piece a welding operation.

Results:-

‘ welding with the help of arc welding fixtures reduced time for production of the component and also reduce the fatigue effect on worker due to ergonomically convenient for the operation

‘ with help of fixture effective clamping is done more accurate than the conventional method.

‘ the circular indexing plate gives rotational movement for the front side, topside weld more easier than the conventional method in which worker have to move the work piece as per the weld position.

— Page 39

‘ the hand cutter provide the facility to cut the frame or bar while the work piece clamped on the fixture

‘ in conventional method first worker to arrange accurately before weld of frame while in fixture with help of locator work piece automatically locating

‘ this fixtures increases the productivity, accuracy, reliability

Futures scope:-

In the above arc welding flexible fixtures various futures scope are as under

‘ Provide power driven or automatic movement of the circular indexing plate which reduces the worker fatigue.
‘ Here we only indexing up to the180 degree while with help of other clamping arrangement 360 degree indexing possible.
‘ The clamping surface are of the flat which only locate the flat work piece for provide V-shape at the end also possible for the circular work piece.
‘ To provide the scale on the slotted plate we adjust the clamp as per work piece size

— Page 40

5. REFERENCES:

Research paper:

‘ Design of Fixtures: A Review By Nisarg Parmar IJARIIE-ISSN(O)-2395-4396
http://www.ijariie.com
‘ A Review on Design of Fixtures by Shailesh S.Pachbhai & Laukik P.Raut International Journal of Engineering Research and General Science Volume 2, Issue 2, Feb-Mar 2014 ISSN 2091-2730
‘ Design of Welding Fixtures and Positiners
Prof. S.N.Shinde, Siddharth Kshirsagar, Aniruddha Patil, Tejas Parge, Ritesh Lomte
International Journal of Engineering Research and General Science Volume 2, Issue 5, August-September, 2014 ISSN 2091-2730

Books:

1) Text book of Machine Design by r.s khurmi and j.k gupta s chand publication

2) Text book of Production technology by r.k.jain Khanna publication

3) Production technology by p.c sharma s chand publication

4) Machine Tool Design by N. K. Mehta

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