The value of measuring crimp is overlooked by many technicians. Crimp affects the finishing process as well as such fabric properties as abrasion, strength, and elongation. Even though a fabric has a square construction, that is, the same yarn size in warp and filling and the same number of ends and picks, it will not have balanced strength unless the crimp is the same in both the warp and filling yarns. The crimp percentage is the mean difference between the straightened thread length and the distance between its ends while in the cloth. It is expressed as a percentage. In order to define a crimp, two values are necessary: the length of the cloth from which the yarns are removed and the straightened length of the thread. In order to straighten the thread, tension must be applied, just sufficient to remove all the kinds without stretching the yarn. There is no way to remove all the crimps before the yarn itself begins to stretch in practice. .
The standardized tensions recommended in the B.S. Handbook are given below:
- To know about crimp percentage.
- To know crimp geometry
- Come to learn W.I.R.A crimp tester
- To know how to calculate crimp percentage.
- W.I.R.A Crimp tester
- Fabric sample
Standard testing temperature:
An atmosphere at the prevailing barometric pressure with a relative humidity of 65% and temperature of 200 C is called standard testing temperature.
Preparation of specimen:
At first we have to select the warp and weft way of fabric. Then we select test length of fabric. Here we will take 13*13 inch2 fabric. our crimp length of the yarn is 13 inch. where a higher degree of accuracy is necessary special crimp testers are used . Here we will take 10 threads, 5 for warp way and 5 for weft way. Here we will used The W.I.R.A crimp tester.
- Initially, a dissecting needle is used to separate the central part of the first thread from the flap fringe. However, the outer ends are left attached.
- By removing one end from the cloth and placing it in the tester’s grip, and leaving the other end in the second grip, we can transfer the thread from the cloth to the tester without losing the twist.
- After calculating the standard tension, set the tension in the machine.
- We will now see a gradual increase in tension.
- A scale is used to determine the length of the yarn after tension has been applied.
- From these two lengths, we can calculate the crimp percentage.
- This will enable at least 5 crimp percentages for warp and 5 crimp percentages for weft to be calculated, and the average crimp percentage will be found.
Count of the tested yarn both warp and weft= 30 Ne
For load calculation, we will convert English count to Tex count.
From Warp way, specimen 01
Crimped length of the yarn (p)=13 inch
Un-crimped length of the yarn (l)=13.9 inch
Rest specimen’s crimp percentage is calculated same way that mention above.
Then we calculated average crimp percentage for warp and weft way.
Average warp crimp percentage 4.61%
Average weft crimp percentage 11.38%
From our calculation, we see, crimp percentage of warp yarn is low. Because, warp yarns are kept tension during weaving process. One the other hand, sizing process is done on warp yarn. As a result, strength of warp yarn is high than weft yarn. On the other hand, weft yarns are kept in low tension and use low quality. As result, weft yarn show more crime percentage.
- Booth, J. (2008). Principles of Textile Testing. New Delhi: CBS Publishers & Distributors.
- Corbman, B. P. (1983). Textiles Fiber to Fabric. New York: Mc Graw Hill.
- Hamby, E. B. (1993). Handbook of Textile Test and Quality Control. New York: Wiley Eastern Limited.
- HU, J. (2008). Fabric Testing. New York: Woodhead Publicatioing Limited.