Cyclic Tensile Stress Decay in Wet Spun Flax Sized Warp Yarns
Optimal polyvinyl alcohol and starch size blends limit cyclic tensile stress decay in wet spun flax warp yarns below 15 percent, maximizing high-speed loom efficiency.
Shedding Stress
Shed Tension
Mechanical forces acting on warp yarns during the opening of the loom shed can cause fiber fatigue and yarn breakage. Minimizing shedding stress is essential for maintaining high loom efficiency, especially when using linen yarn which has lower elasticity than cotton. The yarn must withstand both tensile pull and abrasion from the heald eyes as they move up and down to create the shed.
This stress is measured by tension sensors mounted on the warp beam.
Fabric Deformation
Excessive tension on the warp yarns during shedding can lead to localized stretching and structural defects in the manufactured linen. When shedding stress is too high, it causes yarn deformation that results in uneven fabric density and warp-wise striping in the finished cloth. This quality defect is visible after dyeing and can lead to the fabric being downgraded during inspection.
Adjusting the shed height and timing reduces the peak tension on the yarn during each loom cycle.
Loom Optimization
Sizing the warp yarn with starch or polyvinyl alcohol provides a protective coating that reduces abrasion during shedding. This treatment increases the yarn’s resistance to mechanical wear and allows the loom to operate at higher speeds. The optimized settings are recorded in the weaving mill’s standard operating procedures.