Reed Mark of Fabric and Its Relation with Warp Tension at Beat-Up with Different Loom Settings
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Indian Journal of Textile Research Vol.13,September 1988, Pp. 151-157 Reed Mark of Fabric and Its Relation with Warp Tension at Beat-up with Different Loom Settings S K NEOGI and P K BHATT ACHARYYA Indian Jute Industries' Research Association, 17 Taratola Road,Calcutta 700088, India Received 21 August 1987; revised and accepted 20 January 1988 Reed mark of jute fabric with plain weave, expressed as reed mark percentage ({tMP), has been studied with differ- ent loom parameters. Attempts have also been made to find out the relationships between RMP and (a) tension differ- ence between two warp shed lines at beat-up and (b) seepage of the fabric. RMP at fell varies in the same manner as that at grey state of fabric with different loom settings and the relationship between them is linear with correlation coeffi- cient of 0.96. RMP at grey state decreases with earlier shed timing, higher back rest position and change of leasing pat- tern of warp yarns from one-by-one to two-by-two. Beat-up tension difference varies inversely with RMP and the rela- tionship between them is linear with correlation coefficients of - 0.91 and - 0.76 for different shed timings and back rest positions respectively. Seepage of the fabric is directly related with RMP with correlation coefficient of 0.64. Keywords: Jute fabric, Loom setting, Reed mark, Warp tension 1 Introduction 2.1 Measurement of Reed Mark Reed mark or Reediness of fabric is one of the During weaving the warp and weft yarns interlace major faults and, therefore, needs proper care dur- at the fell to form a fabric and the resultant cover of ing weaving. Since jute cloth is mostly used as sacks the fabric depends mainly on the conditions of the for carrying food grains, cement, etc., pore size or yarns at that instance. It was, therefore, considered the cover of the cloth plays an important role in its worthwhile to study the reed mark at the cloth fell practical uses. Methods to overcome reed mark on on the loom to observe its behaviour with varying cloth are fairly known and have been discussed ear- parameters of weaving and then to compare it with lier'<", but no systematic analysis of the effects of the ultimate reed mark of the fabric off the loom. different loom settings on reed mark has been made. Since the fabric selected for study was of much open Snowden? made some studies with cotton fabrics construction with coarse warp yarns (Table 1),inter- and expressed the reed mark quantitatively but he yarn spaces for calculating reed mark were mea- too did not consider the effects of either different leasing patterns or the tension of warp yarns during weaving on the reed mark of the cloth. Table I-e-Particulars of Loom and Fabric The lack of sufficient information on these prob- lems has initiated in undertaking a study, reported Make of 100m Utex (India) here, with plain jute fabrics which are generally of Loom speed 152 ppm Reed space 112.1 ern opener construction and, therefore, more prone to Warp width at reed 107.3 em such defect. Shed dwell 130· The reed mark of the fabric has been expressed in No. of heald shaft Two with sliding wire healds percentage form as reed mark percentage (RMP) Let-off motion Negative friction type and calculated as (A- B)/Ex 100, where A is the Weave Plain (1/1) Ends/dm 39 distance between two warp ends separated by a reed Picks/dm 35.6 wire; and B, the distance between two successive Warp count 275.6 tex warp ends in a dent. Weft count 292.8 tex Denting pattern 2 in a dent for body and 4 in a dent 2 Materials and Methods for selvedge Leasing pattern 1 up-I down and 2 up-2 down Hessian fabric woven on a non-automatic shuttle Reed dent/ern 1.81 loom in UIRA laboratory was used for the study. Ratio of air space to reed The particulars of fabric and loom are given in wire, 0/0 68.5:31.5 Table 1. 151 INDIAN J. TEXT. RES.,YOLo 13, SEPTEMBER 1988 sured between the axes of two successive yarns with back rest could not be set at a level with or below the. the help of an ordinary mm steel rule and a magnify- height of front rest because of the mechanicallirnit- ing glass of power of 5.88 dioptres. To find out RMP atiolls of the loom and hence the effects of loom ~ at fell, inter-yam spaces were measured between the setting with top shed tighter than the bottom could ~ - second and third picks soon after stopping the loom not be compared with those studied by Snowden9. with crank at back centre and front heald down, and The maximum height of back rest with two-by-two to find out RMP at grey state, measurements were leasing could not be set as high as that with one-by- taken after the samples were relaxed for at least 48 one as any attempt to go beyond the height of 11.5 h. RMPs at fell and grey state of each sample are the cm caused the top shed line getting too slack to per- average of six values calculated at six different mit satisfactory weaving. Distances between the places along the width of the fabric, leaving about back heald and front lease rod and between the 7.5 cm from each selvedge and 45 cm from the start lease rods were kept unaltered throughout the . of a sample. The places were so selected that the same Warp Yarns were involved for calculatin g the W E ' arp nds r" ofcorresponding all the samples.values At eachof RMP place, at twentyfell and consecutivegrey state ~ readings of A and B (section 1) were taken. There- LeaseRads fore,of inter-yarn each value spaces. ofRMP is' the result of 120 readings .. 2.2 Loom Setting and Leasing Pattern of Warp Yam BackHeald Loom settings studied to observe their effects Up f h dd ' . d f FrontHeald were timing.. 0 s e mg motIon an posItion.. 0 I 1 : : Down back rest. As shown in Fig. 1, three different posi- I il :1 II ,I ReedDent tions of shed level and heights of back rest with re- A B fr ed 1:;' h h d tim.1st, 2nd, spect to ont rest were arrang .ror eac s e -III LeasingPattern ing and back rest height, three types of leasing pat- T tern, one-by-one (invariably adopted for weaving ': I I jute fabrics with plain weave), two-by-two type 1 (i.e. conventional for cotton weaving) and two-by-two type 2 (i.e. type 1 with rearranged denting), as shown in Fig. 2, were used. Therefore, a total of 27 samples with various combinations of loom setting and leas- ing pattern were woven. As 'shown in Fig. 1, the .I I .::. .::1 . Fell H~dS Lea..Rods ABC 1 0I 1 I .. tI "'~ =r1~~~t"'.~\f\. 1stDent: A-B=Maximum-Minimum'High --?+2'4 ---2nd Dent: C-D=Maximum(-)-Minimum(+)-Low 23 66 8'5 , 2/2, Type 1 Leasinq Pattern .I I I I Value of 'X' I I I 1 1/1LeasinQ 2/2LoasinQ (Type1&2) 3.5cm 3.5 cm 8-5cm 8.5 cm 13-5Cm 11.5cm PS PE S~ED LEVEL -,-- 0'/360'. -,-- 315' 270' I : ' j-I' i BU/S .1 I m .I I I I I I I A 0 C B 1st,Dent: A-D = Maximum-Minimum (+ )aMedium SL 2ndDoot:C-B=Maximum(-)-Minimum=Medium BU-BeatuPjSL Shedlevel;SO-Shedopen 2/2. Type2 LeasingPattern SC-Shed ctosinQ;PS-Pick;nQ slor1sjPE-P jokIng ends Fig. I-Loom settingand timing diagram Fig. 2- Leasingpattern of warpyarns studied 152 NEOGIand BHAlTACHARYYA: REED MARK OF FABRICAND ITS RELAllON WITHWARP 1ENSION study. When the height of back rest was changed the 3 Results and Discussion distances of lease rods from the heald shafts were readjusted. 3.1 RMP at Felland Grey State Table 2 shows the values of RMP at fell and grey 2.3 Measurementof WarpTension state of the samples with different loom settings and For all the 27 cloth samples, tensions of single le~ing patterns. It is observed that RMP of the fa- warp yarn of both front and back heald shafts pass- bncs under any weaving condition changes from fell ing through the same dent of reed were measured to grey state and is generally higher at the former. d~ring weaving at four different places along the Changes i,n RMP are. possibly ?ue to the changesin WIdth of the warp sheet (about 7.5 cm away from the yam spa~mgsan.d cnmp amplitudes of both sets of selvedge) between warp beam and back rest with the yams while passmg from fell to grey state. It is also help of Rothschild electronic tensiometer and Hel- observed that RMP at fell varies more or less in the coscriptor recorder. The chart speed of the recor" same manner as at grey state and the relationship der was 50 minis. Tension recording was done after betw.eenthe ~s at these two stagesis linear (Fig. at least fifty picks were inserted. From the tension 3) WIth the equation, RMP at grey state = 22.70 + chart, ten consecutive peaks (i.e. the maximum ten- 0.68 x RMP at fell and correlation coefficient (r) of sion) at the instance of beat-up were noted for each 0.96, ~hich is statistically highly significant.