Sampling techniques for yarn
In yarn sampling, yarn is collected from a cone or cheese package for or from a fabric sample for the final product test, and from a ring frame or winding machine for ongoing production test.
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| Yarn sampling |
Use of random numbers
Yarn sampling by random numbers method is normally useful for a small number of yarn bobbins which are to be selected from comparatively small bulk sizes.
Generally, yarn for testing is selected from 10-15 packages of consignment at a random level from either the winding unit or the storage unit. (In spinning, make sure it is not selected from a stock of condensed yarn.) (In the case of condensed yarn, some parameters of yarn testing vary. However, condensed yarn testing is separate from ring frame yarn testing.)
In the case of more yarn types of yarn formation or in case of the consignment containing more than five cases, then choose five cases or select at a random level from multiple options.
(This is suitable for large-scale sample testing with a large number of yarn varieties.)
If the consignment contains less than five cases, ten packages are selected at random from all the cases with approximately equal numbers from each case.
The appropriate number of tests is then carried out on each package.
Yarn sampling from cone
Form cone, yarn sampling is done according to the random numbers method.
In case of yarn take up, It is important to not use a 1-2 yard length of yarn as a specimen, from the package starting or from the ending point of the cone package.
Skip a minimum of 1 yard of the distance between two consecutive specimens in a continuous yarn package.
Yarn sampling from fabric
A sampling of yarn from fabric is also very important and widely used to check the quality of fabric and estimate fabric appliances and applications.
During separating threads from fabric, it is vital to consider following rules.
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| Yarn sampling from fabric |
Fabric samples are always taken as the warp and weft separately because often the properties in each direction generally differ.
The warp and weft direction should be specifically marked on each sample before it is cut out for yarn separation. (So, that warp yarn and weft yarn are separated for sampling.)
No two specimens should contain the same set of warp or weft threads. (Otherwise, it will give the same result.)(To find out more accurate results it is vital that we choose the same yarn from the various surfaces of the fabric.)
During thread separation from fabric, it is important to specimen threads are different.
I.e. - For warp thread always select threads parallel to each other. If chosen threads are from the same line then they give the same results.
The same things apply for weft threads, For weft threads always select threads parallel to each other. If chosen threads are from the same line then they give the same results.
In the correct layout, each sample contains a different set of warp threads so that their properties are potentially different depending on the degree of uniformity of the fabric.
As it is the warp direction in this case that is being tested the use of the same weft threads is not important.
Samples should not be taken from within 50mm of the selvedge as the fabric properties can change at the edge and they are no longer representative of the bulk.
It is applicable to use rectangular strips of two warp and five weft samples.
Basically, the size of these strips is 20 inches in width and contains more than 50 threads.
Questions -
- What is random sampling?
- How sampling is done for cone/cheese?
- How sampling is done for fabric?
- What should be kept in while doing sampling for fabric?
References
Lord, P. R. (2003). Handbook of yarn production: Technology, science and economics (1st ed.). Woodhead Publishing.
NPTEL IITm. (n.d.). Nptel.Ac.In. from https://nptel.ac.in/courses/116102029
Saville, B. P. (1999). Physical testing of textiles. Woodhead Publishing.
Testometric co. Ltd. (n.d.). Testometric.co.uk. from https://www.testometric.co.uk/
Yarn tests. (2019, July 23). ATIRA; Ahmedabad Textile Industry’s Research Association. https://atira.in/yarn-tests/
(N.d.). Textilelearner.net. from https://textilelearner.net/classification-of-textile-testing-fiber-testing-yarn-testing-fabric-testing/
Writer - DSPAT Team
