Weft Bar Defect Causes and Prevention
topic
Weft bars are horizontal bands of different weft density visible across the fabric width caused by momentary changes in pick spacing from warp tension spikes, loom speed variations, take-up system hesitation, weft tension changes from package depletion, fell position displacement from loom stops, or periodic warp yarn properties creating cyclic tension variation, with prevention requiring identification of the specific causal mechanism through correlation of bar position with loom events and process data that distinguishes the multiple possible causes producing visually similar defects.
Role
Addresses the most commercially significant fabric quality defect in terms of customer complaints and fabric downgrading, with weft bar prevention requiring the systematic diagnostic approach that correlates visible bar frequency and position with loom operational events and process parameter measurements to identify the specific causal mechanism among the multiple possible causes, enabling targeted correction rather than the generic parameter adjustment that may not address the actual cause.