The purpose of this test is to determine the strength of cotton fiber with the HVI device. Along with length and fineness, one of the most sought-after properties in cotton fibers is strength. Fiber strength directly affects yarn strength. The stronger the fiber used, the stronger the yarn produced. The minimum strength value of usable textile fiber is 6 cN/tex. (TS 1153, BS 5116 )
A sample of sufficient weight taken from the bale can be used in the strength test. samples; It is cleaned by removing foreign materials such as seeds, sand, stems, etc. The samples are conditioned under standard atmospheric conditions.
Fiber length and strength determination are made in the same area of the device. This region; It includes a brushing mechanism to parallelize the fiber, an optical system to measure the length of the fiber sample, and a gripper system to determine fiber strength and elongation.
The following features are determined by the test performed in this section..
1-Fiber strength (g/tex)
2-% fiber elongation
3-Upper half average length
5-Short fiber index
The cotton fiber in the test card is sent to the jaw system where the strength test will be performed after the length determination. The jaws (one fixed, the other movable) hold the sample at a distance of 1/8 inch. The back jaw is pulled at a constant elongation rate until the sample is broken and the fiber strength is determined. Strength measurement results can be given as both Pressley and Stelometer. In addition, the elongation at break value is also determined. The same processes are repeated for the other sample. At the end of the test, the strength and elongation at break values of the samples are given as the average of the two measurements. As a result of the strength test
strength and elongation at break are evaluated according to the tables below.
Strength Values and Evaluation
Stelometer Value (g/tex) Pressley Value PM (1000 pounds / inch2) Deevaluation
20 and below 70 -76 Very weak
21 – 23 77 - 83 Weak
24 – 26 84 – 90 Average
27 – 29 91 – 97 Robust
30 and above 98 – 104 Very robust
Elongation Value and Evaluation
%Elongation Value Evaluation
0-5 Very little
5 – 5,8 Less
5,9 – 6,7 Medium
6,8 – 7,6 High
7,7 - Above Very high