Using Cotton Sliver Draft Force to Evaluate Textile Processing Efficiency, Part I

USING COTTON SLIVER DRAFT FORCE TO EVALUATE TEXTILE PROCESSING EFFICIENCY, PART I

D. D. McAlister, III, J. D. Bargeron, L. C. Godbey

ABSTRACT. Fiber bundles in sliver form more closely represent the fiber bundles commonly used in commercial testing. Therefore, this experiment focused on studying drafting force using untwisted fiber bundles (sliver) rather than twisted fiber bundles (roving) as had been previously studied. Four cottons of similar micronaire but different lengths were utilized for this experiment. Ring spun yarns of three different linear densities were produced from each cotton to cover the range of coarse to fine yarns commonly produced in a textile mill. Fiber quality, processing quality, and yarn quality were measured for each cotton in addition to finisher sliver drafting force. The analysis of the data indicates that short fiber content has the greatest impact on drafting force. In addition, it appears to be possible to determine processing waste and spinning efficiency levels through the determination of drafting force of sliver. Keywords. Cotton, Textile processing, Fiber quality, Short fiber content, Drafting force.

pinning technology is advancing far beyond predict- and against metal (fiber-to-metal) and found a strong rela- ing cotton fiber performance from the fiber proper- tionship (r = 0.85) between fiber crimp and fiber-to-fiber co- ties reported by High-Volume Instruments (HVI) hesion with a RotorRing test method. In earlier work, and used for the marketing of cotton. Currently the convolutions in cotton fiber (similar to crimp in synthetic fi- fiberS properties measured by HVI are length, length unifor- ber) were found to play an important role in the friction be- mity, strength, micronaire, color, and trash. Many researchers tween a single cotton fiber and a straight-edge probe have pursued various methods for measuring other properties (cantilever assembly). Cyclic changes in the frictional force related to the surface characteristics of cotton fiber. Graham occurred at repeat distances between successive convolu- and Bragg (1972), using a draft zone simulation instrument, tions in the fiber (Basu et al., 1978). Lord (1955) found that were able to measure the effect of inter-fiber cohesive forces the coefficient of friction of a fiber tends to increase as the that exist in roving prepared for ring spinning. This research frequency of convolutions increase. Utilizing image analy- was successful in proving that the force (grams) required to sis, a more recent study found that DPL ACALA 90 and draft roving for spinning was highly correlated (r = 0.84) to ACALA MAXXA SJV varieties had a high shape factor and spinning efficiency. Employing the same instrument used in a low number of convolutions per millimeter length of fiber; 1972, Graham and Taylor (1980) showed that a strong cor- whereas, PAYMASTER HS 26 had a low shape factor and a relation (R2 = 0.80) existed between fiber micronaire and high number of convolutions per millimeter length of fiber mean length versus the force (grams) required to draft roving (Han et al., 1998). In a related study, Foulk and McAlister formed from cotton fibers. Work by Ghosh et al. (1992) dem- (2001) showed that Favimat testing of single cotton fibers onstrated the importance of fiber cohesion (friction) mea- from multiple bales revealed that fibers with more convolu- surements for man-made staple fibers. These researchers tions have a higher linear density, tenacity, and elongation. concluded that fiber cohesion was influenced by fiber length, Additionally, Mogahzy et al. (1997) found that increasing finish type (the lubricant on a synthetic fiber) and level, fiber percentages of naturally occurring wax on the surface of cot- geometry, crimp type and level, fiber additives, degree of fi- ton fibers had a negative relationship (R2 = 0.55) with fiber ber entanglements, and fiber surface roughness. In fact, these friction as measured with the RotorRing test method. In cur- researchers were able to quantify the fiber cohesion (mea- rent studies at ARS, Cotton Quality Research Station, Clem- sured in Joules) as it relates between fiber (fiber-to-fiber) son, South Carolina, a strong relationship was found between particular surface metals on cotton fiber and RotorRing fiber-to-fiber and fiber-to-metal cohesion measurements with both relationships being negative with increasing metal Article was submitted for review in June 2002; approved for content on the fiber surface (Brushwood, 2001). Other than publication by the Power & Machinery Division in May 2003. the work carried out by Graham and Bragg (1972), there has Trade names are used soley to provide information. Mention of a trade been no other research relating drafting efficiency to textile name does not constitute a warrenty or an endorsement of the product by processing efficiency and to quality of the end product (yarn). the U.S. Department of Agriculture to the exclusion of other products not mentioned. However, this earlier work was performed on roving which The authors are David D. McAlister III, Research Leader, Jefferson has twist. Most test methods for determining fiber surface D. Bargeron III, ASAE Member Engineer, Agricultural Engineer, and characteristics are time consuming and not practical for nu- Luther C. Godbey, Agricultural Engineer; Cotton Quality Research merous samples. In addition, it is not feasible for a textile mill Station, ARS, USDA, Clemson, South Carolina. Corresponding author: to conduct such tests before making machine-setting deci- David D. McAlister III, Cotton Quality Research Station, ARS, USDA, P.O. Box 792, Clemson, SC 29633; phone: 864-656-2488; fax: sions. Therefore, this work was undertaken to apply the draft 864-656-1311; e-mail: [email protected]. zone simulation utilized by Graham and Bragg to assess the

Applied Engineering in Agriculture Vol. 19(6): 637-640 2003 American Society of Agricultural Engineers ISSN 0883-8542 637 impact of fiber characteristics of different cotton slivers (50/1), 900 rpm (flyer speed); Spinning, 22/1, 36/1, and (which contain no twist) on process quality with respect to 50/1 Ne, 4.0 t.m., 11,000 rpm (spindle speed). The quality process machinery settings. Slivers were chosen in prefer- data for these yarns are listed in tables 2, 3, and 4, ence to roving for this research project in order to remove the respectively, for the yarn counts listed above and represent an influence of twist on the fiber orientation and to use samples average of three replications for each cotton. more closely representing the fiber bundles utilized in com- Additionally, slivers (2nd pass drawing) from processing mercial instrument testing of cotton fiber properties. The first for each cotton were evaluated for drafting force. Drafting part of this study re-examines the impact that commercially force is measured in grams and is an indicator of the force available measured fiber properties have on the force re- required to parallelize the assembled fibers for the next stage quired to draft (parallelize) cotton fibers into a sliver form of processing. Historical data on drafting force measurement and the impact of the force required to draft sliver(s) into yarn between two pairs of drafting rolls are available to verify on processing efficiency and yarn quality. some of the results of this study Graham and Bragg, 1972; Graham and Taylor, 1980. Drafting force was determined by deflection of one pair of rollers in a two-pair draft zone. MATERIALS AND METHODS Deflection was first calibrated utilizing weights in order to determine the representative force required to attain a given Four cottons from the same crop year representing the deflection of the pair of rollers. The corresponding deflection same classer’s grade (31) were utilized for this study. Of the for a given weight was sensed electronically (millivolts) via four cottons, two had the same staple length (35) one was a a linear variable differential transducer (LVDT). Force was staple 33 and the other a staple 37. All cottons had a measured in grams. The calibration is represented by the micronaire of 4.0 ± 0.10. The fiber strength ranged from 25.4 following formula: to 28.5 g/tex. Fiber properties were measured with High Volume Instrumentation (HVI), Advanced Fiber Information System (AFIS), Suter-Webb length array method, and Table 2. Yarn quality of each cotton type for 22/1 Ne. Shirley Fiber Maturity Tester (FMT) and are listed in table 1. Property[a] Cotton 1 Cotton 2 Cotton 3 Cotton 4 The fiber property data represent an average of three replications for each cotton. Waste (%) 8.07 5.78 5.94 8.67 Carded ring yarns were produced from these fibers and the SES (mN/tex) 125.0 153.0 169.0 130.0 qualities of these yarns were assessed by measuring defects, SES C.V. 12.5 9.9 10.5 11.2 mass evenness, strength, appearance, processing efficiency, SEE (%) 7.22 6.37 6.39 6.83 SEE C.V. 10.7 11.2 11.4 18.6 and waste generation. Processing proceeded as follows: C.V. m 25.6 20.8 20.5 22.9 Carding, 60 grains, 31.8 kg/h; Drawing (first pass), 53 grains, Thick places (#) 2578 1256 1214 1739 350 m/min.; Drawing (second pass) 55 grains, 500 m/min.; Thin places (#) 991 233 189 577 Roving, 0.80 Hank (22/1), 1.00 Hank (36/1), and 1.25 Hank Neps (#) 417 131 329 305 EDMSH 14 3 6 10 Table 1. List of fiber properties for each cotton type. [a] Waste = waste generated in yarn processing, [a] Property Cotton 1 Cotton 2 Cotton 3 Cotton 4 SES = Single End Strength of yarn Staple (32nd) 35 35 37 33 SEE = Single End Elongation of yarn UHML (mm) 27.69 27.94 29.46 25.91 Thick places = thick place defects in yarn UI (%) 81.9 83 83.7 81.9 Thin places = thin place defects in yarn Neps = nep defects in yarn Strength (g/tex) 25.4 27.8 28.5 28.3 EDMSH = number of yarn ends out of production in a one thousand Elongation (%) 6.8 6.1 5.2 7.8 spindle hour time period. Micronaire (µg/in.) 4.1 4.0 4.0 4.0 Trash (%) 0.12 .26 0.08 0.12 Color (Rd) 78.3 77.2 78.8 79.4 Table 3. Yarn quality of each cotton type for 36/1 Ne. Color (+b) 9.7 9.1 9.5 8.8 [a] UQL (mm) 29.72 30.48 32.00 27.94 Property Cotton 1 Cotton 2 Cotton 3 Cotton 4 SFC (%) 15.3 8.2 7.6 11.9 Waste (%) 8.07 5.78 5.94 8.67 Fineness (militex) 171.6 162.4 166.4 179.4 SES (mN/tex) 111 138 167 125 Maturity ratio 0.91 0.95 0.92 0.85 SES C.V. 19.9 13.1 13.9 16.0 Neps/g 494 400 277 442 SEE (%) 6.00 5.32 5.69 6.62 [a] Staple = Fiber length measured in 32nds (in.) SEE C.V. 14.8 13.5 9.8 18.9 UHML = Upper Half Mean Length C.V. m 30.3 25.6 23.9 27.3 UI = Uniformity Index (length uniformity) Thick places (#) 3748 2424 1990 2900 Strength = fiber bundle strength Thin places (#) 2697 1218 600 1729 Elongation = fiber bundle elongation Neps (#) 1498 900 1025 986 Micronaire = fiber linear density EDMSH 80.0 22.9 47.6 74.3 Trash = percent foreign matter in fiber sample [a] Color (Rd) = sample color measured on gray scale Waste = waste generated in yarn processing Color (+b) = sample color measured on yellow scale SES = Single End Strength of yarn UQL = Upper Quartile Length (AFIS) SEE = Single End Elongation of yarn SFC = Short Fiber Content Thick places = thick place defects in yarn Fineness = fiber diameter Thin places = thin place defects in yarn Maturity Ratio = fiber maturity Neps = nep defects in yarn Neps/g = number of neps in a 1 gm sample of fiber. EDMSH = number of yarn ends out of production in a 1,000 spindle hour time period.

638 APPLIED ENGINEERING IN AGRICULTURE Table 4. Yarn quality of each cotton type for 50/1 Ne. 68 66.8 Property[a] Cotton 1 Cotton 2 Cotton 3 Cotton 4 67 66.11 Waste (%) 8.07 5.78 5.94 8.67 66 65 SES (mN/tex) 97 130 129 103 63.69 64 SES C.V. 18.9 15.2 16.2 18.8 62.84 SEE (%) 5.53 5.48 4.69 6.08 63 62 SEE C.V. 14.9 11.5 13.6 14.2 (g) Drafting Force C.V. m 33.3 29.1 26.5 30.0 61 60 Thick places (#) 4486 3379 2704 3674 Thin places (#) 3884 2129 1254 2734 1234 Neps (#) 2429 1643 1477 1643 Cotton Type EDMSH 961.3 24.2 64.3 702.2 Figure 1. Measured drafting force from sliver for each cotton. [a] Waste = waste generated in yarn processing SES = Single End Strength of yarn SEE = Single End Elongation of yarn process. Short fibers tend to “clump” together as thick places Thick places = thick place defects in yarn along the length of a sliver and float uncontrolled in a drafting Thin places = thin place defects in yarn zone. Cox (1948) showed that when a thick place arrives at Neps = nep defects in yarn the front roll, a greater than normal draft is required. EDMSH = number of yarn ends out of production in a 1,000 spindle Yarn mass evenness (C.V.m) deteriorates (increases) hour time period. when a high force is generated during drafting. High force with uneven drafting would result in more thin (weak) Grams Force = 0.00177(millivolts) - 0.444 (1) segments and thick segments along the length of the fiber assembly. Although not statistically different for this data set, The spacing between roller pairs was set according to the the trend of better yarn quality is consistent with the length of fiber for each condition to avoid fiber breakage differences in drafting force between low draft-force condi- between the nip points of the two pairs of rollers. Roll spacing tions (better quality) and high draft-force conditions (poorer was set 4 mm longer than the measured Upper Quartile quality). Length (table 1) for each condition (as is the standard practice Poor drafting (high force) also results in more fiber lost as in setting draft roll spacing for short staple fiber spinning). waste because the fibers are not properly aligned and are The draft was held constant at 5 by reducing the speed of the poorly controlled in the fiber assembly being drafted. Within back roll pair to 5 times less than the speed of the front roll the data set of this study, there is a significant relationship pair. Roller speed was measured in rpm; with the front roll (R2 = 0.885) at the 0.06 level between drafting force and the pair turning at 115 rpm and the back roll pair turning at amount of waste generated during processing as shown in 23 rpm. The drafting rolls have a diameter of 2.54 cm, which figure 2. results in a delivery of 9 m/min as calculated below: Poor drafting of an assembly of fibers results in thin and Surface speed (m/min) = (2) thick places along the mass of fibers as discussed previously and as indicated by the poor yarn evenness and defect level ×p [roll diameter(cm) ] rpm of roll in the high draft-force conditions. These yarn characteristics 100 are also reflected in good or poor spinning efficiency. This Eight thousand data points were collected for draft force efficiency, as measured by spinning ends down per thousand- for each sample. Data was analyzed for mean differences and spindle hour (EDMSH), deteriorates as drafting force correlation via Analysis of Variance. increases regardless of the nominal linear mass of the yarn made. This relationship is depicted in figures 3, 4, and 5, respectively, for 22/1, 36/1, and 50/1 yarn counts at R2 = 0.950 or above at the 0.02 level. RESULTS AND DISCUSSION An Analysis of Variance for the comparison of sample means was significant (p < 0.05). A Tukey post-hoc test was SUMMARY then used to determine which sample means of the drafting The purpose of the first part of this study was to conduct force for pairs of the test cottons from all four cottons were similar work by Graham and Bragg (1972) and Graham and significantly different (at p < 0.05). The results (fig. 1) indicate that drafting force is the same for cottons two and 9 three and likewise for one and four. Further, drafting force for 8 cottons two and three is significantly lower (d min = 1.273) at the 0.05 level from cottons one and four. Of all the fiber 7 properties listed, only short fiber content (SFC) has a 6 y = 0.7302x - 40.244 significantly strong relationship (R2 = 0.881) at the 0.06 level with drafting force with respect to this particular data set. 5 R2 = 0.885 Long cottons tend to be more uniform than short cottons and (%) Waste Processing therefore are better aligned during the drafting process. The 4 data indicate that an increase in short fiber results in an 62 63 64 65 66 67 increase in drafting force. The implication is that a broader Drafting Force (g) distribution of fiber length in an assembly of fibers creates Figure 2. Correlation of drafting force and processing waste. more tension in the strand being aligned by the drafting

Vol. 19(6): 637-640 639 60 1000 900 50 800 700 40 600 500 30 400 300 y = 243.01x - 15324 20 y = 9.2545x - 570.48 2 200 R = 0.9722 2 100 10 R = 0.953

Ends Down/1000 Spindle h. 0 62 63 64 65 66 67

Ends Down/1000 Spindle h. 0 62 63 64 65 66 67 Drafting Force (g) Drafting Force (g) Figure 5. Correlation of drafting force and spinning ends down for Figure 3. Correlation of drafting force and spinning ends down for 50/1 Ne. 22/1 Ne. efficiency from bundles of fibers (sliver) with a high degree Taylor (1980) to verify the impact of cotton fiber properties of confidence without having to physically process fibers into on measured drafting force but through the use of a different yarn to make these determinations. This preliminary work assembly of cotton fibers (slivers), which more closely lays the foundation for more extensive work incorporating represents fiber bundles, used in commercial fiber testing. more fiber property variables, including fiber surface The impact that the drafting force for those slivers has on characteristics as has been done in the synthetic fiber processing and yarn quality was also studied. Micronaire was industry. held constant and within the normal tolerance (±0.10) for the measurement of micronaire as established by the Agricultur- al Marketing Service (AMS, 2001). Classer grade was the REFERENCES same for all cottons used in this study. AMS. 2001. The classification of cotton, cotton division, Unlike what was demonstrated by Graham and Taylor agricultural marketing service. Washington, D.C.: Agricultural (1980), fiber length did not have a significant affect on Marketing Service. drafting force. However, SFC did have a significant effect Basu, S., A. Hamza, and J. Sikorski. 1978. The friction of cotton and is an indication of the distribution of fiber length in an fibres. J. Text. Inst. 69(2): 68-75. assembly of fibers. Brushwood, D. E. 2001. The influence of surface materials on raw Although measured yarn quality was not statistically cotton processing friction. Proc. of the 2001 Beltwide Cotton different for each of the conditions in each of the three yarn Conf., 1291-1294. Memphis, Tenn.: National Cotton Council of counts, the trend in yarn quality follows with the significant America. differences in drafting force for slivers from each of those Cox, D. 1948. Fiber movement in drafting. Textile Res. J. 39: conditions. In addition, within this data set, it appears that it 230-240. Foulk, J., and D. McAlister. 2001. Favimat analysis of single cotton would be possible to predict processing waste and spinning fibers. Proc. of the 2001 Beltwide Cotton Conf., 1261-1267. Memphis, Tenn.: National Cotton Council of America. 90 Ghosh, S., J. E. Rodgers, and A. E. Ortega. 1992. Rotor ring 80 measurement of fiber cohesion and bulk properties of staple 70 fibers. Textile Res. J. 62(10): 608-613. 60 Graham, J. S., and C. K. Bragg. 1972. Draft force measurement as 50 an aid to cotton spinning. Textile Res. J. 42(3): 175-181. 40 Graham, J. S., and R. A. Taylor. 1980. The relationship of drafting 30 y = 13.969x - 850.54 force variability to cotton fiber properties and spinning 20 R2 = 0.954 efficiency. Textile Res. J. 50(5): 271-275. 10 Han, Y. J., Y. J. Cho, W. E. Lambert, and C. K. Bragg. 1998. 0 Identification and measurement of convolutions in cotton fiber

Ends Down/1000 Spindle h. 62 63 64 65 66 67 using image analysis. Artificial Intelligence Rev. 12: 201-211. Drafting Force (g) Lord, E. 1955. Frictional forces between fringes of fibers. J. of the Textile Institute 46: 41-58. Mogahzy, E. Y., R. Broughton, H. Guo, and R. A. Taylor. 1997. Figure 4. Correlation of drafting force and spinning ends down for 36/1 Ne. Cotton fiber friction: The unknown quality of cotton. Proc. Beltwide Cotton Conf., 545-552. Memphis, Tenn.: National Cotton Council of America.

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