Warp Tension Control on Loom

                          It is desired to obtain constant uniform warp tension across the width of the warp. Since during fabric formation, low warp tension creates clinging that causes unclear passage for the filling. While high tension increases yarn breaks. Detecting and controlling the optimum warp tension will maximize the weaving efficiency, improves fabric quality, fabric dimensional stability due to better ratio of warp crimp to weft crimp and enhances the uniformity of color shade. The running tension should be at a value neither to over-elongate nor to entangle the yarn .

Loom warp tension and its variability depend on following factors......

1.  Applied force on warp yarns by back rest roller to the warp tension.
2. The radius of back rest roller.
3. The vertical position of back rest roller.
4. The horizontal position of back rest roller.
5. Variation in warp beam radius during weaving from full to empty beam.
6. Fabric structure.
7. Warping speed variability & warp tension.
8. Building uniformity of warp beam.
9. Material properties.
10. Machine type.

Warp tension curve is the result of.......Let off, take up, shedding and beat up actions. Weaving motions cause warp move back and forth through reed, heddle eyes and drop wires which stretch and looser warp yarn within weaving cycles.

The warp breakage during weaving not only depends on the strain but other factors such as big knot, missing/cross ends, thick places, slub, etc. also play a major role. Experimental results show that the strain on the warp yarn during a pick cycle, which is maximum during full shed open condition and

at beat up, can be minimized by incorporation of a spring loaded, self rotating reciprocating backrest and by increasing the free warp length.

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