The Crimp in a yarn is defined as the mean difference between the actual length of any yarn and its apparent length in the fabric after weaving. It is usually expressed as a percentage of the apparent length of the yarn in the fabric.
Determination of the crimp of yarn is carried out by marking a known length on the fabric, removing the marked yarn in such a manner that to dose not lose its twist, holding between two grips at the marked points, and slowly extending it till it is subjected to a specified straightening tension. The increase in length of yarn is determined and expressed as a percentage of markedlength to obtain the value of crimp.
My Q Crimp tester is designed to determine the crimp of yarns taken out of fabrics. One end of the yarn is held in a pivoted loading grip on which the desire tension load is applied by means of a sliding weight acting on a lever arm, while the other end is held in a movable grip which is mounted on a screw and can move along the direction of the yarn, stretching it in the process. the distance moved through by this grip gives the extension of the yarn, and can be measured ona scale fixed by the side of the grip assembly.
The loading grip is pivoted on jewel bearing and mounted on a slider platform which can be moved toward or away from the moving grip to enable different marked length of yam to be tested. The test length is indicated on scale fixed on the base of the apparatus against a pointer fixed to the sliding platform.
The yam is held in between the two grips and pulled by moving the movable grip away from the loading grip. The tension under which crimp is to be determined is set on pendulum by moving the sliding weight and is indicated on a load scale. When the yam is under the specified tension, the pendulum lifts off its support, thus breaking a contact and turning off a low voltage indicator light. The elongation of the yarn when the light just goes off is noted, from which the valve of percentage crimp can be calculated.
Relevant Standard - Is 3442-1966 : Method for Determination of Crimp and Count of Yarn Removed from Fabrics
|Maximum test length||400mm|
|Maximum elongation||125 mm|
|Tension load||3gm to 20 gm|