Sunday, January 27, 2019

BROKEN PICK IN THE FABRIC, A FABRIC DEFECT, A WEAVING DEFECT, CAUSES, AND REMEDIES

BROKEN PICK IN THE FABRIC:


"If weft yarn gets absent in the middle of the fabric for a short length, it is called a broken pick". See below graphic. The main factors generating broken pick and their remedies are given below:



Causes and remedies of broken picks:

1 - A broken-pick defect in the fabric occurs mainly due to the poor quality of the weft yarn and loom settings. 

2 - The thin places present in the weft yarn can generate broken pick in the fabric. If weft yarn has low strength, then it causes broken pick. When the weft yarn passes between the top and bottom layer during picking, a certain tension is applied to weft yarn. The weft yarn having poor tensile strength and excessive thin places doesn't able to bear the tension and gets broken in the middle of the fabric. 

3 - Loom setting plays a great role in the generation of a broken pick in the fabric. Shed crossing timing (a loom position at which the ends of the top and bottom layer are levelled) directly affects the frequency of this defect. Early shed crossing timing always creates a chance of broken pick in the fabric. As soon as the loom reaches the shed crossing position, the tension on the weft yarn reaches up to the maximum. In this situation, the weft yarn doesn't able to bear the tension and gets broken in the middle of the fabric. 

 4 - If the receiving gripper releases the weft yarn later than required, this kind of situation can create broken pick defect in the fabric.how does it happen? When receiving gripper is about to exit from the shed, the shed starts to get closed and  crossing position, the warp ends grip the weft yarn completely. Here late weft release by gripper pulls the weft yarn. Thus chances of broken pick get increased. 

5 - If the frequency of this kind of defect in the fabric is high, then fabric gets rejected. Weaver should always be very careful about this kind of defect.
                               
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