Study of drafting force variability and sliver irregularity at the break draft zone of a draw frame

Abstract

To produce an evener fiber assembly, it is important to understand fiber dynamic behavior during the drafting process. Drafting force and its variability is an alternative approach to understand the fiber's velocity-friction characteristics, representing a combined effect of multiple fiber properties. In this study, online drafting force and its variability was measured with different break draft ratios and back roller gauges to analyze its effect on sliver short-term evenness. Drafting force variability well correlated with sliver evenness with correlation coefficient R 2 ¼ 0.81. The coefficient of variation (CV%) of drafting force was highest (2.3%) at low break draft 1.1-1.2, and then reduced gradually to its minimum value (1.5%) around a break draft of 1.6-1.7. The minimum variability of drafting force well corresponds with lower irregularity of sliver at certain break draft ratios. This indicates that a stable drafting force promises better fiber distribution along the sliver length. The variability of drafting force and sliver irregularity also increased as the back gauge increased from 43 to 51 mm. Furthermore, the impact of short fiber content on the drafting force was investigated at three back gauges. The increase in short fiber content gives higher magnitude of drafting force. Drafting force was also compared with the number of neps and change in fiber length in sliver for each break draft. Better nep opening and improved fiber lengths were also found around (1.6-1.7) break draft and follow the same trend of variability of drafting force as the break draft changed.Keywords variability of drafting force, sliver irregularity, break draft ratio, short fiber content During the drafting process, lack of control on the motion of each fiber results in more or less irregular fiber arrangement. The variability in fiber properties, especially in natural fibers, create difficulties in producing more even fiber assemblies. In pursuit of a single parameter, which can represent overall velocity-friction characteristics of fibers, researchers came up with the measurement of drafting force and its variability.Drafting force is the direct and intuitive factor resulting from fiber motion in the drafting zone. Many researchers have investigated the drafting force, describing it as a force required for pulling out the highspeed fibers from the low-speed ones, causing fibers to slide past one another. 1,2 Studies on the effect of various parameters on drafting force, such as fiber crimp, length and fineness, 3,4 and draft setting, such as draft ratio, drafting speed and top roller pressure, 5-7 have been reported.The force required to draft a sliver depends on the frictional properties of its constituent fibers. Moreover, the fiber behavior during the drafting process depends on these frictional forces and, more specifically, on the variation of frictional forces. 8 The drafting force and its variation can be a source of information as they are consequential of intricate fiber cohesion mechanisms. 9 Drafting force variabil...

Fiber motion and the accelerated point distribution in roller drafting

“…When the break draft was in the draft range between 1.24 and 1.56, the accelerated point distribution was more focused, and this corresponds to the previous study. 16,17 After conducting the F-test to test the fitness of the model to the experimentally observed accelerated point distribution, the Gaussian distribution model was proved to fit significantly. As for the lognormal distribution, the encircled part in Table 6 shows the p-value, which is higher than , and its corresponding F-value, which is smaller than the F-critical value, hence the lack of significance in the fitted model.…”

Optimization of Break Draft, Pin Spacer and Rubber Cots Hardness to Enhance the Quality of Ring Spun Yarn Using Factorial Design

“…Various studies were conducted regarding drafting parameters of spinning systems to improve the yarn quality [5][6][7]. The drafting parameters of ring spinning that affect the quality of yarn are drafting angle and spinning triangle (both relate to spinning geometry) [8][9][10], draft amount, draft (break and main draft) distribution [11], drafting roller setting (front and back zone gauge) [12,13], top rubber coated roller hardness (front and back) [14], cradle length, cradle arm pressure [13,1], aprons hardness (top and bottom), spacer size and spacer type (nose type and pin type). Each mentioned parameter contributes to the quality of spun yarn [16].…”

Investigation into novel drafting systems on ring spinning frame for improving yarn properties

“…Sun et al 8 and Ma and Wang 9,10 proposed the model of fiber arrangement in the time domain to simulate the roller drafting process, which sheds light on the sliver dynamic behavior in the drafting zone. Siddiqui and colleagues 11,12 measured the online drafting force and its variability with different break draft ratios and back roller gauges, and demonstrated the relationship between the fiber length and the drafting force to analyze its effect on sliver short-term evenness.…”