The Comparative Study Of The Newest Capacitance Evenness Testing Method And Sight Inspection Method About Short Fiber Yarn

Yarn evenness is one of the key indicators to measure yarn quality．Capacitance evenness tester is thestandard instrument for evaluating the yarn quality, and it is also used to test of yarn evenness CV, yarn defects,and so on. The detection results which capacitance evenness tester makes can be used to evaluate the quality ofthe yarn.The blackboard evenness tester is the traditional tester which is used to test yarn evenness. Sightinspection method is also listed as the one of the national standard to evaluating the yarn quality.This paper isto discuss the relativity between these two kinds of detection methods of yarn evenness, and study thedifferences among these two methods.First of all, this paper studied the stability of the two kinds of evenness detection methods, the resultsshow that the USTER TESTER5has very high stability. Uster Technology Co., Ltd rules areUSTER TESTER5test ten times in each sample has high reliability. Blackboard evenness grade CV andStability times of blackboard evenness tester is low, the stability of the test results is high. But the Sightinspection method is influenced greatly by human factors. Further analysis of test results is that the values ofthe CV and stability times of polyester yarn were less than cotton yarn. Secondly，Use USTER TESTER5and blackboard evenness tester to test three kinds of sample which including100%cotton ring spun yarn,100%cotton compact spun yarn and100%polyester ring spun yarn. And then use simple linear regression toanalysis the results of two tests.Using curve fitting method to analysis the relativity between the yarn evennessCV and blackboard evenness grade, and then found that the best fitting model is cubic model (three times), butthe coefficient of determination was low.Based on analyzed values, a multiple regression equation wasgenerated. The results of relativity between yarn evenness CV and Blackboard evenness grade is better thensingle regression analysis. Then through the use of enter method and stepwise method in the results of100%cotton ring spun yarn and100%cotton compact spinning yarn and100%polyester ring spun yarns, theexpression of the corresponding equation is obtained.The results of100%cotton compact spinning is betterthan100%cotton ring spun yarn and polyester ring spun yarn at a certain degree. And it also indicates that theindicators of the electronic evenness tester have relativity with blackboard evenness grade.According to the results of the multiple regression analysis, we make further classification of the testingresults of the samples in accordance with shape grade, yarn count grade.Under the same conditions, analysisresults show that, The higher number of the shape, the better relativity between yarn evenness CVm andBlackboard evenness grade. What’s more，due to the number of shape value of the100%cotton compactspinning yarn and100%polyester ring spinning spun yarn were higher than those of100%cotton ring yarn, sothe determination coefficient which between yarn evenness CVm and Blackboard evenness grade of the100%cotton compact spinning yarn and100%polyester ring spinning spun yarn is larger than that in100%cotton ring spinning yarn.In the solution of yarn count, if the yarn is thinner, the relativity between yarnevenness CV and the blackboard evenness grade is higher.And the number of determination coefficient whichbetween the result of100%polyester ring spinning yarn are highest of this three kinds of simple,100%cottoncompact spun yarn second and the lowest is the results of100%cotton ring yarn. The uncertainty of measurement to capacitance evenness tester and blackboard evenness tester wereevaluated.The results show that the uncertainty degree of capacitance evenness tester depends on the samplesof uniform and representative, and test instruments of measurement error. And the uncertain degree ofblackboard evenness tester mostly depends on the uniformity of samples and representative, followed, as wellas tester’s error.