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The Influence of the Ginning Process on Seed Cotton Properties

ABSTRACT

The aim of the present study was to evaluate the impact of ginning process on the quality properties of seed cotton. The ginning process were carried out on the ginning Egyptian seed cotton (extra-long staple) Giza 86 that was mechanically picked up. The saw gin-stand machine (Lummus type) was operated at four saw drum speeds (i.e., 3.14, 3.77, 4.4, and 5.03 m/s) and   four levels of feed rates (i. e., 4, 6, 8 and 10 kg.min-1) under four different fiber moisture content (i.e., 10.2, 8.8, 7.4 and 5.9 %) to determine the effect of those parameters on the Performance of saw gin stand machine, lint quality properties and The impurities percentage. The results revealed that the fiber moisture content of 7 % achieved the best lint quality properties and minimum impurities percentage. The highest ginning efficiency of 86.7 % and the lowest gin stand lint losses of 0.33% associated with saw drum speed of 4.4 m/s, feed rate of 10 kg/min and lint moisture content of 8.8 % d.b. Also results showed that Strength was inversely proportional to the saw speed; while elongation was proportional to saw speed. The maximum value of the impurities percentage (3.6%) recorded at saw speed of 5.03 m/s, feed rate of 10 kg/min and moisture content of 10.2%.

INTRODUCTION

Ginning is the most important process to separate the seed cotton into lint (fiber) and seeds. Ginning not only preserves the fiber quality but also dramatically improves the market value of cotton price. About 85% of total cotton in the world is ginned by saw gins stand machines (Rafiq and Chaudhry, 1997). The operating parameters strongly affect the performance of ginning machines and the lint properties of cotton. The amount of water that fibers contain can greatly affect their physical properties (McCreight et al. ,1997). The absorption of moisture by cotton fibers changes the mechanical and frictional properties of cotton, which affects the behavior of fibers in-process (Morton and Hearle, 1997). Byler (2003) reported that for cotton ginned with three moisture treatments of seed cotton before the gin stand, the AFIS fiber length-related properties were significantly improved with moisture restoration before the gin stand. Increasing the fiber moisture content by 1% increased the mean fiber length by 0.8 mm. Anthony (1985) discussed different features of a ginning machine, such as the control and maintenance along with the humidity of the cotton, he found that the humidity have a significant effect in limiting the deterioration of cotton seed and cotton fiber quality. Hossam El din (1978) and Eweida et al. (1984) found that the seed cotton feed rate significantly affects the capacity and the non-lint content. Columbus and Mangialardi (1996) found that high feeding rate resulted in high non-lint content in the ginned lint. Hughs et al. (1983).Anthony and Brag (1987) studied the effects of varieties, harvesting regimes and ginning practices on the fiber length, and the distribution of ginned lint. They reported that in order to minimize short fiber content and to achieve acceptable market grades, cotton should be harvested twice-over with as little weathering as possible and no more than one lint cleaner should be used at the gin. Perter and Wahba (1999) found that the short fiber content of ginned cotton is relatively correlated with fiber elongation, lint content, strength and uniformity ratio of seed cotton Anthony(1989) reported that processing cotton at a gin to minimize machinery usage and to maximize monetary returns requires a thorough understanding of the performance characteristics of individual machines. A database involving multiple moisture, trash, machine and cotton levels was developed for all routine and laboratory fiber properties before and after various ginning processes. Ranges of these variables were representative of the minimum and maximum levels normally found in spindle-harvested cotton. The database is suitable for multiple regression analyses and development for predicting equations based on the performance characteristics of individual and combined machines. Mangialardi and Anthony (2000) found that, cotton fibers are cleaned at gins with saw-type lint cleaners to improve the market value, but the aggressive saws sometimes harm the quality of  fibers. The cleaning efficiency of one saw-type lint cleaner was 54% on average and the efficiencies of seed cotton cleaners used as lint cleaners ranged from 9 to16%. There was a significant improvement in the classer's leaf grade designations when lint was cleaned with saw-type cleaners. Staple lengths tended to be shorter after cleaning with saw-type cleaners. A modified non-saw cleaner appears to be more practical and could help preserve fiber quality at cotton gins. McAlister (2001) compared a traditional gin with an intelligent to evaluate fiber quality and subsequent yarn quality. The Intelligent utilized one incline cleaner and one lint cleaner while the commercial gin includes an impact cleaner, a stick machine, an incline cleaner and one lint cleaner. He found that cotton ginned by the intelligent produced yarn with higher strength than that ginned by the commercial gin. Intelligent required less ginning, which therefore reduced short fiber content and created manageable trash particles. Patil et al. (2006) compared a foot operated gin and a Lilliput gin having ginning output capacity of 0.311 and 2.111 kg lint/h, respectively. The 2.5% span length and uniformity ratio remained practically the same for hand ginning. So, the foot operated gin is much more suitable for farmers because it is economical and auxiliary power is not required for its operation. Whitelock et al. (2007) developed and evaluated a simple and useful prototype machine for ginning Egyptian cotton in laboratory scale. This could help technicians and scholars to study the effect of any treatments during operation on fiber cotton quality. The objective of this study was to determine the optimal conditions for the operation, which achieved the lowest rate damage and lost in the cotton ginning using a saw gin machine (Lummus type) and study the effect of ginning process on the technological characteristics of ginned cotton.

MATERIALS AND METHODS

Field experiments were conducted at Arab gin in El-hamra city, Kafr El-Sheikh Governorate to evaluate the performance of saw gin-stand machine, Lummus Gentle Ginning System type. The general components parts are shown in (Fig.1) and cross section shown in (Fig.2) that is using in ginning process of Egyptian cotton varieties (extra-long staple). The (Cotton variety G 88) that mechanically harvested has been used in ginning process. Table1 summarizes the technical specifications of saw ginning machine. This machine having saws and ribs made from metal mesh (Fig.3A); the gin stand consists of a set of saws rotating between the ginning ribs (Fig.3B). This technique made the ginning as continuous flow process rather than batch process. Cotton enters the saw gin stand through the huller front. The saws grasp the cotton and draw it through widely spaced ribs known as huller ribs. The locks of cotton are drawn from the huller ribs into the bottom of the roll box. The actual ginning process, separation of lint and seed, takes place in the roll box of the gin stand. The ginning action is caused by a set of saws rotating between ginning ribs. The saw teeth pass between the ribs at the ginning point. Here the leading edge of the teeth is approximately parallel to the rib, and the teeth pull the fibers from the seed, which are too large to pass between the ribs.

Table 1: Description of the technical specifications of saw ginning machine ( Lummus Gentle Ginning System type)

Description Item No.

U S A Machine made of 1

 2150 Overall length(front, with covers), mm 2

1383 Overall width (with covers), mm 3

1043 Overall height(front to bottom of feeder), mm 4

815 (Approx.) Weight of the machine , Kg. 5

750 Production capacity per one hours (approx.), Kg / hour 6

730 Saw Shaft center line to floor, mm 7

2 nos. v-belts Type & Nos. of Driving Belts 8

21 nos. (16 ball bearing, 2-roller

bearings & 3-needle roller bearings) Type & Nos. of Bearings 9

25 hp Power required 10

 600 Minimum distance between machines, mm 11

2360 x 1720 x 1170 mm Floor space required (including electric motor), mm 12

150 g. Grease per 8 hrs.(approx.) Type & consumption of lubrication 13

from rear Removal of Cotton Lint 14

by helical gears Driving of Roller Shaft 15

90 Saw blades, number 16

20 Doffing brush number, (rows of brushes) 17

320mm dia., 950 rpm Doffing brush diameter and doffing brush speed 18

400 mm dia., 350 rpm Saw diameter and saw speed 19

 However, ginning at rates higher than that recommended by the manufacturer usually causes reduction in fiber quality, seed damage and choke-ups. Gin stand saw speeds are also important factor; high saw speeds tend to increase the fiber damage during the ginning process. Accordingly the experimental studies were accomplished to evaluate the performance of the gin machine under three different variables as follow:

1-Saw drum speeds: four speeds were used in this study, namely: 3.14 (150 rpm), 3.77 (180 rpm), 4.40 (210 rpm) and 5.03 m/s (240 rpm).

2-Feed rates: four feed rates of 4, 6, 8 and 10 kg/min.

3-Cotton moisture content: the experiments were carried out at three different levels of cotton moisture content, namely: 10.2 %, 8.8 %, 7.4 % and 5.9 %.

The moisture content was determined by using the oven method according to (ASHRAE, 1999) and the following formula was used:

%  ''..........(1) 100, x M1   -      M2 =   Moisture content

M2

 Where: M1 = the moist mass (g) and M2 = the dry mass (g).

Measurements:

1-Ginning outturn: The percentage of ginning outturn was determined by using the following formula:

Ginning outturn, % = Lint mass, kg ''''''' ( 2 )

Seed cotton mass, kg

2- Gin lint losses

Total weight of ginned lint losses was determined by using the following formula:

Gin lint losses, kg = Weight of sample before ginning ' (lint productivity, + weight of seed wastage) '''' (3)

                                                              

Fig. 1: Saw gin-stand machine(Lummus Gentle Ginning System model)

                                               

                                         SEED COTTON

Lint

Fig. 2: General arrangement and principle operation of the cotton saw gin.

 

A

B

Fig. 3: Saw cylinder and ginning bars (metal mesh) photography.

3- Ginning efficiency %

The ginning efficiency was determined by using the following formula:

Ginning efficiency, % = Seed cotton mass before ginning ' seed wastage mass ..' (4)

Seed cotton mass before ginning

Where, seed wastage mass is the seed cotton mass without ginning.

4 - The physical and mechanical fiber quality properties

The Physical and mechanical fiber properties were determined at fiber testing laboratory, Cotton Research Institute (CRI), Agriculture Research Center (ARC), Giza as follows:

(a) Fiber length: The digital fibrograph model 630 was used to determine 2.5 and 5% span fiber length according to May and Bridges, (1995).

(b) Uniformity ratio: it was expressed on uniformity quantity between short and long fiber length. And it was determined by using the following formula:

    -------------------------- (5)

 (c) Lint Color: HVI 9000 according to ASTM (D-1684-96) estimated the lint color (reflectance Rd, % and yellowness +b)

(d) Fibers strength and elongation: Measured using stelometer instrument at fiber testing laboratory, CRI, ARC according to (ASTM, designated D-1445-75, 1984).This instrument gives elongation reading and cotton strength that can be determined by using the following formula:

''(6 ) 100 '' 1.5 '' mass of  cutting fiber

= Strength for length unit, g/tex

mass of sample

(e) The impurities percentage: Determined by using fractionator instrument in the cotton ginning research division, CRI, ARC.

RESULTS AND DISCUSSION

A) Performance of saw gin stand machine:

1- Lint turn out, %:

Data of lint turn out as affected by the different variables considered is shown in Fig. 3 .The lint turn out was observed to increase with increasing both of saw drum speed and feed rate. Decreasing the lint moisture content from 10.2 to 7.4 % tends to increase the lint turn out however, the lint moisture content of 5.9 % decreased the turn out . Results also noticed that, the maximum value of lint turn out (46.2 %) recorded at saw drum speed of 5.03 m/s, feed rate of 10 kg/min and lint moisture content of 7.4%d.b.; while, the minimum value (34.6 %) recorded at saw speed of 3.14 m/s, feed rate of 4 kg/min and lint moisture content of 10.2 % d.b.

Fig.3: Effect of saw drum speed, feed rate and lint moisture contents on ginning turn out      

2- Determination of saw gin stand optimum operating conditions:

Results in Fig. 4 illustrate the ginning efficiency and gin lint losses at all variable levels. Ginning efficiency increased with increasing feed rate and with decreasing moisture content; on the contrary, it was decreased with increasing saw drum speed. On the other hand, gin lint losses percentage increased with increasing the saw drum speed and feed rate; while it decreased with deceasing lint moisture content.  Intersection points between the ginning efficiency curves and the lint losses curves can determine the optimum conditions for machine operating; which it gives suitable efficiency with less ginning percentage of lint losses. Signing the ginning efficiency and gin lint losses curves graphically is possible to identify the optimum conditions for the saw gin machine. Accordingly the optimum operating condition for saw gin stand was recorded at saw drum speed of 4.4 m/s, feed rate of 10 kg/min and lint moisture content of 8.8 % d.b. These conditions produced a ginning efficiency of 86.7 % and gin stand lint losses of 0.33%.

Fig. 4: Effects of saw drum speed feed rate and lint moisture contents on ginning efficiency and gin lint losses percentage.       

B) Effects of saw gin stand on the lint properties and quality:

1-Seed cotton fiber length, mm:

Fiber length is considered an important factor that determines the cotton price in the markets. Fiber length is classified into the average fiber length, mm at 2.5% and 50% distribution pattern. Figs. 5 and 6 illustrate the effect of saw drum speed, feed rate and fiber moisture content on the fiber length at 2.5% and 50% in the normal distribution curve. It is clear that the 2.5% and 50% span fiber length is proportional to the lint moisture content and feed rate and inversely proportion to sow speed at all other variables. The maximum average fiber length of 32.5 mm at 2.5 % in the normal distribution curve and 16.1 mm at 50 % in the normal distribution curve were recorded at saw drum speed of 3.14 m/s, feed rate of 10 kg/min and fiber moisture content of 10.2%.

   2. Fiber length uniformity ratio, %:

Uniformity is considered as important fiber property along with the length and grade where they affect the industrialization efficiency and properties of threads. Fiber length uniformity as affected by different variables is shown in Fig. 7. The percentage of uniformity decreased with increasing saw drum speed and decreasing the moisture content. Meanwhile it increased with increasing feed rate at all combination of other variables. A maximum length uniformity of 49.5% was recorded at ginning cotton mechanically at saw drum speed of 3.14 m/s, feed rate of 10 kg/min and fiber moisture content of 10.2%.

Fig. 5: Effects of saw drum speed, feed rate and lint moisture contents on fiber length, mm at 2.5% at distribution pattern.

Fig.6:  Effects of saw drum speed, feed rate and lint moisture contents on fiber length, mm at 50% distribution pattern.

3. Color grade:

  Seed cotton color grade is divided into two components, seed cotton color reflectance, % and seed cotton color yellowness, unit. Figs 8 and 9 indicated that the highest values of color reflectance (Rd) was 74.1% associated with the saw drum speed of 5.03 m/s, feed rate of 4 kg/min and fiber moisture content of 5.9%.  On the other hand, the lowest values were 6.2 unit recorded at saw drum speed of 5.03 m/s, feed rate of 4 kg/min and fiber moisture content of 10.2%. On the contrary, cotton reflectance was increased by increasing saw speed and with decreasing both of feed rate and fiber moisture content. Meanwhile, cotton yellowness was decreased by increasing both of saw drum speed and moisture content and with decreasing feed rate.

Fig. 7: Effects of saw drum speed, feed rate and lint moisture contents on fiber uniformity ratio at ginning process.

Fig. 8: Effects of saw drum speed, feed rate and lint moisture contents on fiber reflectance (Rd) at ginning process.

Fig. 9: Effects of saw drum speed, feed rate and lint moisture contents on fiber yellowness (+b) at ginning process.

4.  Cotton Strength and Cotton Elongation

Cotton strength (g/tex) and cotton elongation (%) are considered as extent standard for using the cotton fiber in the cotton industries. Fig. 10 presented the effect of the saw drum speed, feed rate and moisture content on the cotton strength and its elongation .The results indicated that, cotton strength decreased with increasing the saw drum speed and decreasing fiber the moisture content; while it increased with increasing the feed rate at all combination of other variables. The maximum seed cotton strength of 29.5 g/tex, recorded at the saw drum speed of 3.14 m/s, feed rate of 10 kg\min and fiber moisture content of 10.2%. Conversely, the minimum seed cotton strength of 26.7 g/tex, recorded at the saw drum speed of 5.03 m/s, feed rate of 4 kg/min and fiber moisture content of 5.9%. In addition, Fig. 10 illustrated that, the cotton elongation proportional to the saw drum speed and inversely proportional to the feed rate and the moisture content. The maximum elongation of 8.4%, recorded at the saw drum speed of 5.03 m/s, feed rate of 4 kg/min and fiber moisture content of 10.2%. However, the minimum elongation of 4.7%, recorded at the saw drum speed of 3.14 m/s, feed rate of 10 kg/min and fiber moisture content of 5.9%. This may attributed to exposure the fiber to little impact at these conditions.

Fig. 10: Effects of saw drum speed, feed rate and lint moisture contents on the cotton strength and its elongation during ginning process.

3. The impurities percentage, %

Fig. 11 illustrated that, the impurities percentage increased with increasing both of the saw drum speed and the feed rate; while, it decreased with decreasing the moisture content. The maximum value of the impurities percentage of 3.61% recorded at saw drum speed of 5.03 m/s, feed rate of 10 kg/min and fiber moisture content of 10.2% .The minimum value of the impurities percentage of 0.7%  recorded at saw drum speed of 3.14 m/s, feed rate of 4 kg/min and fiber moisture content of 7.4%.

Results concluded that, the gin stand machine produced a law value of the impurities percentage after ginning; this could be achieved because of the high efficiency of the machine parts used in the ginning process.

Fig. 11: Effects of saw drum speed, feed rate and lint moisture contents on the impurities percentage during the ginning process.

CONCLUSION

The performance of a gin stand machine was evaluated by investigating the effect of the saw drum speeds, feed rate and moisture content on the seed cotton fiber quality and its properties. Specific conclusions of the study include the following:

' Lint turnout is proportional to the saw speed, feed rate and inversely proportional to the moisture content. The maximum value of lint turnout of 46.2 % recorded at saw speed of 5.03 m/s, feed rate of 10 kg/min and moisture content of 7.4 %.

' The maximum fiber length at 2.5% and 50% in the normal distribution curve were 32.5 mm and 16.1 mm, respectively; recorded at saw drum speed of 3.14 m/s, feed rate of 10 kg/min and fiber moisture content of 10.2 %. The percentage of length uniformity was 49.5% at the above conditions.

' The maximum value of color reflectance (Rd) (74.1%) was recorded at saw drum speed of 5.03 m/s, feed rate of 4 kg/min and fiber moisture content of 5.9 %. On the other hand, the minimum value of color yellowness )6.2 units(  was achieved  with a saw drum speed of 5.03 m/s , feed rate of 4 kg/min and fiber moisture content of 10.2%.

' Strength was inversely proportional to the saw speed; while elongation was proportional to saw speed. The maximum value of the impurities percentage of 3.6% was associated with the saw speed of 5.03 m/s, feed rate of 10 kg/min and moisture content of 10.2%.

' The optimum operating conditions for the Jumbo saw gin stand machine were recorded at saw drum speed of 4.4 m/s, feed rate of 10 kg/min and lint moisture content of 8.8 % d.b.

References

Anthony, W.S. 1985. Effect of gin stands on cotton fiber and seed Cotton. Gin and Oil Mill Press.; 86(16): 14-18.

Anthony, W.S. 1989. Performance characteristics of cotton ginning machinery .Paper, American Society of Agricultural Engineers.; ( 89-1010): 26 pp

Anthony, W.S. and C.K. Brag (1987). Response of cotton fiber length distribution to production and ginning practices. Trans. of the ASAE 30 (1): 290-296.

ASHRAE (1999). ASHRAE handbook, heating, ventilating and air conditioning applications, inc. SI Edition.

ASTM (1989). Designatians:64,(1634-96). American society for testing and materials. Standards of Textile Testing and Materials. Society, Philadelophia, USA.

ASTM, Standards (1984). Designations: 1445 ' 75. American society for testing and materials. Standards of textile testing and materials .The society, philadelaphia, USA.

Byler, R.K. (2003). Moisture restoration for seed cotton, two approaches. p. 767-771. In Proc. Beltwide Cotton Conf., Nashville, TN. 6-10 Jan. 2003. Natl. Cotton Counc. Am., Memphis, TN.

Columbus, E.P. and G.J. Mangialardi (1996). Cotton seed moisture and seed damage at gins. Trans. of the ASAE 39 (4): 1617-1621.

Eweida, M.A.; G.A. Morshedi; M.A, Risk and S.S.Marzook (1984). Effect of the rotary knife gin 'stand adjustment and cleaning the cotton lint on ginning efficiency in some Egyptian and upland cotton varieties. Agric.res.rev. 62(6): 301 '311.

Hossam El-din, A.E. (1978) ginning efficiency as affected by cotton characteristics and some other major factors. Ph.D thesis. Fac. of Agric. Al 'azhar Univ.

Hughs, S.E., M.N. Gillum and W.F. Lalor.1983  Fiber quality from a combination gin-lint cleaner.Paper, American Society of Agricultural Engineers. ( 83-3533): 15 pp

Mangialardi, G.J. and W.S. Anthony 2000.  Engineering and ginning: feasibility of applying seed cotton cleaning principles to lint cleaning. Journal of Cotton Science. 4(3): 183-192.

May, O.L. and B.C. Bridges, Jr. (1995). Breeding cottons for conventional and late planted production systems. Crop Sci., 35: 132-136.

Patil, P.G., S.K. Shukla and V.G. Arude 2006.  Design development and performance evaluation of portable cotton ginning machines. AMA, 37(1): 30-34.

Perter, M.A. and F.T. Wahba (1999). Assessing ginnability of Australian cotton fiber. Trans .of the ASAE.  42 (4): 853 '857.

Rafiq-Chaudhry, M. 1997. Harvesting and ginning of cotton in the world. Proceedings Beltwide Cotton Conferences, New Orleans, LA, USA, January, 1997, Volume 2 : 1617-1619.

Whitelock, D.P, C.B. Armijo, G.R.Gamble and S.E. Hughs 2007.   Survey of seed-cotton and lint cleaning equipment in U.S. roller gins. USDA - ARS Southwestern Cotton Ginning Research Lab, 300 E College  Journal of Cotton Science. 2007; 11(3): 128-140.

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