Indian Journal of Textile Research Vol. 4, June 1979, pp. 63-70 Detailed Analysis of Carding Quality and Its Influence on Processing and Yarn Properties S K NERURKAR- The Bombay Textile Research Association, Bombay 400086 Received 17 June 1978; accepted 22 April 1979 Detailed analysis of card web/sliver and other post-card products has been done for obtaining improved understanding about the changes in the characteristics of card web/sliver with carding quality and the impact of carding quality on the pro- perties of yarn spun on different spinning systems. The analysis has shown that although the routine tests of carding quality such as trash in sliver, neps in card web, cylinder load, etc. assist in grading carding quality, other card web characteristics such as evenness in card web weight per unit area, short term variation in sliver thickness, fibre parallelization, fibre to fibre separation are also important parameters of card web contributing to carding quality. Although bad carding gives better parallelization, the rate of improvement in parallelization in the subsequent processes is better with good carding, probably due to better fibre separation. Fibre separation seems to influence carding quality more than fibre parallelization. The size of trash particles does not change much with carding condition. Open end spinning has been found to be more sensitive to carding condition both for performance and yam quality than ring spinning. These findings suggest that by carding material under adverse conditions many carding quality characteristics other than the routine ones get changed and the influence on spinning performance and yarn quality depends on the spinning system used. Although the influence of carding quality on post- discovery of hooks in card web by Morton and carding processes and yarn quality is well accepted, the Summer", hook measurement and configuration of term 'carding quality' has not been defined precisely. fibres in a sliver were studied by several workers. This is due to incomplete understanding about the Simpson and Fiori8 found that both hooks and fibre different measurements required to fully describe parallelization must be measured to characterize the carding quality and also due to many non-measurable card sliver and processing performance. The concept of characteristics of card web in a routine manner. The card loading was developed by Kaufmann", while need to have a more detailed understanding for carding Krylov'? devised a simple method for measuring quality is now felt due to the phenomenal increase in transfer efficiency. These different parameters of production rate of card, when carding quality becomes carding quality did not seem to encompass all the critical at such rate, and also due to the advent of many determinants of carding quality. new spinning systems in recent years which may Although the routine tests of card web such as neps, require different configurations of fibres in a sliver than trash particles and cleaning efficiency help to grade the for ring spinning for better performance. Recently, carding quality to some extent, and the same were Ashnin 1 developed a high speed method for assessing emphasized more in the past, not much information is web quality, while Sundra and Swiech" tried to relate available as to how with the deterioration in carding the purity of card web to yarn properties. Ul'man" tried quality evenness in card web weight per unit area, short to evaluate card web quality by counting the number of and long term variation in sliver thickness, fibre holes containing neps on the web deposited on the separation and fibre paralle1ization, etc. are affected at plate. Barella and colleaguest-" developed an card stage and also at subsequent stages. In an attempt electronic instrument for measuring the unevenness to get a better understanding of the subject of carding and neps in card web, while Jackowski" measured fibre quality, card web and its post-card products obtained distribution across the flat carding surface. After the under widely different carding conditions have been examined in detail. The changes in different characteristics of card web/sliver due to carding -This work was carried out by the author at the Southern conditions have also been examined and their influence Regional Research Center of United States Department of Agriculture at New Orleans, USA, while pursuing the fellowship on spinning and yarn quality has been studied. It is sponsored by the World Association of Industrial & Technological envisaged that this approach may help in improving Research Organisation, Vancouver, Canada. understanding of carding quality to some extent, 63 INDIAN J. TEXT. RES., VOL. 4, JUNE 1979 although it may not suggest any new definition of spindle hours for each count. As the hank of card sliver carding quality. was different for the two carding conditions, the same was adjusted to a common hank of 0.16 Ne in two post- Experimental Procedure card drawing passages in steps. Blowroom laps of 140z/yd made from two The part of the material after the second drawing American cottons, Middling (clean) and Low Middling was spun on Toyoda OE spinning with 5.19 and (dirty), were processed on Whitin metallic card with a 5.23 TM for 12/1 and 24/1 counts respectively, and at Crosrol doffer take off and crush roll attachment under 34,000 rpm rotor speed and 6000 rpm opening roll two different carding conditions. The fibre properties speed. End breakage study on OE spinning was ofthe cottons are given in Tablel. The card particulars conducted on 20 rotors and for 80 spindle hours. are given in Table 2. The card sliver was given two The fibre and yarn properties were determined by passages of drawings, then processed on roving and methods recommended by the American Society for two carded counts, i.e. 12/1 and 24/1, were spun on Testing and Materials 11. Sliver uniformity was tested Robberts ring frame with 4.2 TM and at 9100 and on the Saco-Lowell sliver thickness tester converted to 12000 (rpm) spindle speed respectively, on 2.25 in electrical recordings 12. The 'between length' measure diameter ring. The ringframe used was with 240 was 1in and the 'within length' measure was 1yd. The spindles and end breakage study was conducted for 720 CV% of 20 one-yard samples was averaged for a test. Sliver and roving evenness and yarn imperfections and uniformity were measured on Uster IIevenness tester Table I-Fibre Properties at standard recommended speeds for the respective materials. Middling Low Middling Fibre hooks were measured by cutting ratio and Length fibre parallelization by projected mean length on Classer's, in 1-3/32 1-1/16 SRRL triple clamp instrument'". The sizes of dust particles were measured using a Coulter counter. The Digital jibrograph 2.5% span length, in 1.08 1.06 percentage card waste was calculated by processing 50% do 0.47 0.46 200 lb of lap cotton for each trial. Five readings of Uniformity ratio 43 43 cylinder load, flat load and transfer efficiency, equally Micronaire reading 4.60 4.60 spaced in the entire duration of trial, were taken for each trial. Transfer efficiency and cylinder load were Stelometer Zero gauge, g/tex 40.3 41.8 measured by Krylov method 10, while flat load was 1/8 in gauge, g/tex 22.6 23.0 estimated by actual weighing of the flat strips from 15 Elongation, % 8.43 7.28 flats removed by flat comb during normal working. The number of neps and trash particles was counted by Shirley analyzer template method. For each trial, 36 readings were Trash, % 0.82 2.87 taken for nep and trash study. The variation in weight of card web per unit area was calculated by weighing 40 Table 2-Card Processing 'Particulars for Good and Bad web pieces of 4 x 4 in size. This was done by Carding Condition sandwiching the card web at the front of cros-rol of card, between a pair of plastic sheets of appropriate size. Carding condition Good Bad Speed and production parti- Results and Discussion culars on card Hank of blowroom lap fed to card 0.00136 0.00136 Card waste study-The results of card waste study _Licker in, rpm 745 450 given in Table 3 show that under bad carding Cylinder, rpm 300 185 condition less waste is removed than under good DolTer, rpm 20.8 25.8 carding condition. This has resulted in poor cleaning at Flats, in/min 5.5 0.875 Hank of card sliver 0.167 O.lll card under bad carding condition, as seen from the Total mechanical draft at"card 122.4 81.6 lower cleaning efficiency. Grains per yard of card sliver 50.0 75.0 N ep count and variation in weight of card web per unit Production rate at card, lb/hr 30.0 56.0 area-The numbers of neps and trash particles in card web and CV% in weight of card web per unit area are Card settings Flat to cylinder, 0.001 in 10 34 given in Table 4. Under bad carding condition, higher All other settings Normal Normal numbers of neps and trash particles are obtained at card stage with both the cottons. Variation in weight of 64 NERURKAR: CARDING QUALITY & ITS INFLUENCE ON PROCESSING & YARN PROPERTIES card stage due to carding condition got narrowed Table 3-Percentage of Card Waste and Cleaning Efficiency down as the rate of improvement of parallelization in of Card at Different Carding Conditions the subsequent process was higher with good carding, possibly due to better fibre to fibre separation Middling Low Middling (obtained with good carding) and lower degree of (clean) (dirty) parallelization obtained with good carding.