Determination of Twist in Double-Ply Yarns
  • Determination of Twist in Double-Ply Yarns



    The purpose of the experiment is to determine the twist amount of double-ply ring yarns, natural and artificial, spun from staple or filament fibers, by direct counting method..(TS EN ISO 2061) With this method, the twist amount of the yarns produced by the Open-End rotor spinning technique cannot be determined.




    It is applied to give the fibers a permanent appearance, to increase the contact surface with each other, and to keep the fibers together. The fibers in parallel with the twist add strength to the yarn. A twist is given to the yarn in each turn of the twisting element.

    Twist is expressed by the number of turns per unit length (such as laps/m, laps/inch, laps/cm). The amount of twist to be given to the yarn varies depending on the type of yarn (cotton, polyester, viscose, etc.), the place where it will be used (weaving, knitting, etc.) and the spinning machine used (ring, rotor, air-jet, friction, etc.). The twist is given in the S (left) or Z (right) direction.


    Used materials


    Standard atmosphere conditions, yarn sample, needle, tensioner weights, twist measuring device; ( It basically works according to the twist shortening (open/close) method. The twist measuring device basically consists of two yarn clamping jaws, one movable and the other fixed. The movable jaw can rotate in both directions and a counter is mounted on it. Distance between the jaws It can be changed depending on the length of the sample.There is a mechanism in the device that will take the elongation resulting from the opening of the twist and a mechanism that can hold the yarn in a certain tension between the jaws.)


    Sample preparation


    While the test samples are being taken, the area where the twist is to be measured should be determined so that the yarn twist does not change. should not be handled. When sampling from batch production, 5 bobbins or cops are selected as samples. The first 5 meters of the yarns in each bobbin or cop are not used as samples and are discarded because of the possibility that the twist may have changed due to the looseness of the yarn. Test samples are taken at random intervals greater than one meter across the yarn. Usually 10 test samples and 50 cm test length are sufficient for each yarn taken from the bobbin or bobbin. In addition, yarn samples should be conditioned for 24 hours under standard atmospheric conditions. The amount of tension obtained by attaching a weight (tex/2 grams) equal to half the yarn number in Tex is used as a standard.




    Experimental Procedure


    The twist direction of the yarn is determined. A yarn sample of at least 10 cm in length is held in a vertical position between the thumb and forefinger of both hands. Bend to the right with the right hand. If the yarn twist opens and the yarn loses its strength or the fiber becomes parallel at the ends, it is a “Z” twist. If there is an increase in the twist of the yarn, it is “S” twist. The measuring range in the bending measuring device is adjusted according to the distance specified in the standard between the movable jaw and the rotating jaw. The test piece is held by taking care not to deform the twisting and it is pulled through the guides to reach the rotating jaw and the test piece is placed in the gripper jaws with a pre-stress equal to (0,5 ± 0,1) cN/tex. Then half of the yarn count (in tex) is attached to the yarn end. The movable jaw is brought to the "0" position.


    Excess thread is cut off and discarded. Yarn properties are entered into the twist measuring device. (yarn number, twist direction, blend number) Twist measuring device is operated. The movable jaw starts to rotate to open the yarn twist. The opening created by the needle placed between the yarn layers is taken from the left to the right jaw and the yarn layers are completely separated from each other. As soon as the yarn layers become parallel, the movement of the rotary jaw is stopped. When the test is finished, the twist value is observed on the screen on the device. The twist value is determined according to the test method. Sample results are noted separately. It has an average bend.





    Determination of Twist in Double-Ply Yarns
    Posted by %PM, 21% 621% 2016 16%:%May in Quality control Read 4031 times

Determination of Twist in Double-Ply Yarns