Thursday, December 6, 2018

BROKEN END IN THE FABRIC, MISSING END IN THE FABRIC, A WEAVING DEFECT, CAUSES AND REMEDY

MISSING END IN THE FABRIC AND BROKEN END IN THE FABRIC, A FABRIC DEFECT, A WEAVING DEFECT, CAUSES, AND REMEDIES:

BROKEN END:

"If an end gets absent in the fabric for a short in length in the fabric, then this kind of defect is termed as a broken end". See below graphic.




MISSING END:

"If the end gets absent for long in length in the fabric, then this defect is called missing end". See below graphic.



Possible causes of this defect are poor yarn quality (strength, the degree of yarn twist, elongation, hairiness and yarn imperfection), improper selection of drop wires, improper setting of warp stop motion, dirt deposition on the drop wire and electrodes of warp stop motion.

The warp yarn quality greatly influences the frequency of broken end or missing end in the fabric. We know that warp yarn goes under minimum possible tension during weaving. This tension increases more when the loom reaches to fully open shed position. Jerk is also generated on the warp during weaving. If the warp yarn used in the fabric is not able to absorb the jerk and not able to wear the minimum possible warp tension, then the rate of warp breakages goes high. This high breakage rate results in the form of a broken end. Thus the warp yarn should have enough strength to wear the jerk and tension both. The warp yarn should have low imperfection because a thin place in the yarn always has a chance to break during weaving.

The hairiness of the warp yarn also helps to increase the frequency of broken end in the fabric. When an end breaks, the drop wire falls on the electrode and loom stops after one or two loom revolutions. But sometimes loom take little much time to stop and the warp end entangled with adjacent end due to excessive hairiness of warp yarn before falling of drop wire on the electrode. Thus loom continues to run and causes broken end. The same situation creates if the yarn has excessive degree yarn twist.

If the warp yarn does not have enough elongation, then it may be a serious cause of high warp breakage rate. This increased rate results in the form of the high frequency of broken end defect in the fabric.

The selection of the thickness of drop wire has a big concern with warp breakage rate. The thickness of drop wire is selected according to the warp count. If the thickness is lower than enough, then loom takes much time to stop after warp break. Hence the frequency of broken end increases. If the drop wire has more thickness than required it put excessive tension on the warp and results in the form of increased warp breakage rate. Thus it helps to increase the frequency of broken end defect in the fabric.

The setting of drop wire stand directly affects the efficiency of warp stop motion. The distance between drop wire stand and last heald shaft should be as minimum as possible. The clearance between drop wire and electrode should always be minimum. Drop wires and electrodes should be clean. Any type of dirt and dust deposition cause failure of warp stop motion.

If the drop wire has not been put on any end during a pinning and when this end breaks, then missing end generates in the fabric.

A total failure of warp stop for some period also causes missing end defect in the fabric.

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