In this experiment, it was aimed to determine the average length, length uniformity and short fiber index values of cotton fibers with the HVI device.
( TS 715 ISO 6989 )
Length is one of the most important physical properties of textile fibers. Although it is an inherited feature in natural fibers such as cotton, this feature, which is also under the influence of environmental conditions to some extent, affects fiber quality and thus yarn quality. Fiber length gives information about the purpose for which cotton can be used in the textile industry. Long fibers of the same number become a more regular and high-strength yarn. The effect of fiber length on quality varies according to the spinning methods applied. Fiber length affects quality by 35% in ring spinning.
Yarn properties affected by fiber length:
1-spinning limit
2-strength
3-unevenness
4-Attitude
5-Brightness
6-Hairiness
7-Productivity.
Used materials
standard atmospheric conditions, HVI (High-Volume Instruments) tester (measures fiber length based on the intensity of rays passed through a fiber bundle)
Sample Preparation
A sample of sufficient weight taken from the bale can be used for fiber length testing. samples; It is cleaned by removing foreign materials such as seeds, sand, stems, etc. The samples are conditioned under standard atmospheric conditions.
Experimental Procedure
The length test is selected on the computer. The device that prepares the sample is called a fibrosampler.
A sufficient amount of sample is left in the sample preparation unit next to the device and the cover of the device is closed. Cotton fibers, which are picked up from a random place by the rotating brush of the fibrosampler, are pulled through the perforated cylinder and placed on a comb. The samples on the test comb are brushed in order to separate and clean the short fibers on them and to align the remaining fibers, and the non-adherent fibers are removed. After the samples are brushed, they are transported to the optical scanning zone. The fine comb is delivered to the area where the measurement will be made. With the help of an infrared light source, the length is measured and saved on the computer. This process is repeated for other samples. By exposing the fiber bundle in the comb to the fibrograph light, the number of fibers extended to a certain distance can be determined by using the intensity of the light passing through the fibers. As a result, the length distributions of the fibers forming the cotton sample are determined. The same processes are repeated for the other sample. At the end of the test, the upper half average length of the fibers, the length uniformity and the short fiber index values are given by the device as the average of the two measurements. The evaluation according to the length uniformity is made according to the table below.
Uniformity Assessment
uniformity Evaluation
77 and below Very bad
77 – 79 Bad
80 -82 Average
83 – 85 Good
86 – Above Very good
Evaluation Based on Fiber Length
Fiber length (mm) Evaluation
Short fiber shorter than 26 mm
26 - 29 Medium fiber
30 – 38 Long fiber
39 and up Very long staple
SFI (Short Fiber Index) Evaluation
SFI (Short Fiber Index) Value Evaluation
5,0 - 6,0 Very good
6,1 - 7,9 Good
8,1 - 9,9 Medium
10 and above Bad
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