DIFFERENT METHODS OF HAIRINESS TESTING

Methods of Testing Yarn Hairiness ;-

The measuring principle is based on evaluation with diffetacted light . Hairiness value H is defined as the total length of all fibers ends sticking out in cms.

There are different method of yarn hairiness testing as follows

Ref:-https://www suessen.com.y

1) Preliminary remarks:-

Measuring yarn hairiness is most precisely i.e. determining all fiber ends sticking out and not embadded in the yarn body has significantly gained in importance in the last years.

Continuously increasing yarn processing speed and many high end product require yarn with a hairiness reduced to a minimum. The introduction of compact spinning on an industrial scale has furthermore enhanced the general sensivity to most precise evaluation of hairiness of staple fiber yarn.

image of yarn hairiness mresurement.

2) Demands to the measuring technique of yarn hairiness:-

Generally speaking, fiber ends sticking out from the yarn body are inevitable in  the spinning yarn from staple fibers , and simultaneously they are one of its essential characterstics compared with other yarns. While many short fiber contributes substantially to a good touch long hairs can disturbs considerably in subsequent process, cause high additional costs and impair the appearance and practical properties of the textile articles.

Fibers longer than 2 mm can already disturb subsequent process. So if a fundamental distinction between desired an adequate measuring method should be able to represent this difference with utmost accuracy and reliability.

3) Current  measuring methods:-

Three different measuring device are currently available;

Hairiness Module for UTS by M/s Zweigle Hairiness Tester G-566 by M/s Zweigle laserspot LST-111 by M,/s Keisokki. Whereas Hairiness module and within the usual Uster evenness test , the Zweigle device has been developed exclusively for hairiness measurement. The Keisokki laserspot permits to check apart from hairiness yarn diameter and evenness.

Fig.2 Principle of optical hairiness.

4) Description of method:-

All three measuring device operates according to an optical principle and have the disadvantage in common that values are determined by a two diementional projection , where by the absolute (extended) length of the fibers sticking out cannot be exactly measured, but only the rectangular, maximum distance of the hair end from the yarn body.(fig.2)

4.1) Uster Tester 3-H :-

The great advantage of this method is that hairiness parameters are obtained simultaneously with the usual evenness test at Uster Tester 3-H. So there is not must testing expenditure.

The measuring principle is based on evaluation with diffetacted light. Hairiness value H is defined as the total length of all fiber ends sticking out in cm related to a section of 1 cm in length. 

Furthermore, the device gives information on standard deviations SH of the hairiness value H and provides diagram and spectrogram.

This method is very suitable to locate machine failures, which influence yarn hairiness. Hairiness is counted on both sides of the yarn silhouette. As a recent result , tested value have a rather high reliability. But finally, it is impossible to differentiate and classify the fiber ends sticking out.

As the device uses an infrared laser one cannot exclude influences by light absorption.

image of measurement of yarn hairiness usin Uster ref. by Research Gate.

4.2) Hairiness tester G-566 :-

The special device to determine yarn hairiness applies the photo-elctronic principle. Fiber sticking out sensed by diodes as shadows. Twelve diodes are arranged at a distance 1,2,3,4,6,8,10,12,18,21,and 25 mm from the yarn body.

Classification is made according to the actual length i e. a 3 mm long hair is counted in class S3 only , althoug the diodes firb1&2 mm also detect the hair.

The device supplies a histogram showing the number of fiber ends in each length in addition, the S3 value is determined which adds up all fibers end of 3 and more mm.

It is of disadvantage that the fibers stickinh out are counted on one side of the yarn only . The resulting high variations of the measured valuess can be limited by corresponding test repetition.

4.3) Laser spot LST 111 tester:-

The measuring method by means of laser permits a very precise separation of the often diffuse outer yarn layers and short fibers sticking out. Hairs are detected on both sides . This device is able to measure simultaneously the variation of both yarn hairiness. Hairs can be determined in 3 optional length class . Furthermore a hairiness value Ha is indicated, which is defined as the total length in mm of all fibers, sticking out related to yarn section of one cm.

Value Ha is therefore in the range of one power of ten higher than the known value H according to Uster.

In addition, the device offers various othe evaluation option like thin and thicks or related between yarn diameters and hairiness, and this is the most suitable to locate machine defects.

However , classifying hairs in the three length classes only is often insufficient for an over all evaluation of yarn hairiness in the sense of item 2.

4.4) Comparative measurement:- 

A correlation analysis showed a very good compatibility of Laser spot LST 111 with UT-3 H and G-566. It was also found , however , that there is no correlation between Zweigle G-566 and Zell weger UT-H device .

This means is practice that a yarn tested with UT-3 H can be classified quite differently from a yarn tested with G-566.

Customer experience shows that for developing specific products with compact yarn it is inevitable to have a hairiness measurement that can differentiate between individual length classes.

image measurement of yarn hairiness ref:-by Textilebeducation.

Ref:-https://www.fiber2fashion.com.