Twist is the spiral arrangement of fibers around the axis of the yarn in terms of the nominal length of the gauge before opening and is preferably expressed in terms of the number of twists per meter (TPM).
Determination the amount of twist in Twisted Filament Yarn (TFY or TFO)
The twist tester consists of a pair of clamps, one of which can rotate (with adjustable speed) in both directions (clockwise or counterclockwise) and is directly connected to the counter. The adjustability of this clamp allows the user to adjust the length of the test sample as desired. This device is also equipped with a system for applying pretension to the test sample.
Video of the steps of performing this test in the laboratory of Sirang Co.
Among the existing standards in the field of yarn twist measurement, we can name the international standard ISO 2061 or ASTM D1423, or the national standard of Iran No. 32.
The steps of performing test for determination the amount of twist in Twisted Filament Yarn
To determine the yarn twist, it is first necessary to determine the yarn twist direction according to the national standard of Iran No. 11261 or ISO 2: 1973 that is expressed as S or Z. After that, a certain length of yarn is placed between the clamps of the machine and a certain pretension (0.05 cN/dtex) is applied to the yarn using the available weights.
Then other test parameters such as test method; direction of warping, speed of rotational clamp, test length, and yarn linear density are given to the machine and then the machine is started.
It is worth mentioning that in order to achieve a valid and reliable result, it is necessary to repeat this process for a larger number of samples.
The output of the device includes information such as the number of twists per meter, mean of twists, twist factor, coefficient of variation, etc., which can be viewed on the device panel and printed using a printer.