Calculating Loom Reed Width from Warp Crimp and Fabric Sett
Calculating correct loom reed width requires combining off-loom grey contraction, finished warp sett, and weft crimp percentage into one unified formula.
Weft Take-up
Thread Shortening
Percentage shortening of a weft yarn as it paths through the warp shed during weaving measures the structural crimp imparted by interlacing points. Fabric designers compute weft take-up to calculate actual yarn consumption per pick and predict woven width contraction. The metric expresses the difference between the straight yarn length before weaving and the straightened yarn length removed from the fabric, divided by the straight length.
Application covers woven fabric design, ending when weft insertion operates without warp interlacing as in laid triaxial non-wovens.
Crimp Mechanics
Shed opening parameters and warp thread tension dictate the degree of weft bending across the weave pattern. High warp tension forces the weft yarn to flex heavily around warp ends, increasing weft take-up percentage. Plain weave structures exhibit higher weft contraction than loose satin weaves due to frequent interlacing.
Consumption Calculation
Accurate yarn budgeting requires factoring contraction rates into raw material procurement orders. Underestimating weft take-up leads to yarn shortages during full production runs on high-speed air-jet looms. Designers calculate linear yarn requirements based on crimp testing of grey fabric samples.
Fabric Width Effect
Weft structural contraction interacts with fabric width relaxation off the loom. Finishing treatments that shrink warp yarns alter weft take-up values by altering interlacing geometry. Mill technicians measure crimp removal on straightened pick samples to monitor finished fabric density.