Optimizing Shed Height Settings for Air Jet Linen Fabric Construction
Optimizing air jet linen shedding requires asymmetric harness levelling at 26 millimetres to balance relay nozzle clearance with tension limits.
Nep Frequency
Fibre Tangle
Mechanical carding and hackling of raw flax can create small, knotted clumps of short fibres in the sliver. This density of imperfections is measured as the nep frequency, expressing the number of knots found per gram of material. Spinners use this value to assess the quality of the carded linen sliver before it enters the drawing frames.
Spinning Influence
Poorly maintained carding pins or excessive speeds during the hackling process generate a high rate of fibre entanglement. A high nep frequency reduces the spin-ability of the flax roving, causing frequent breakages in the wet-spinning frame. When these tangled knots pass into the spinning zone, they block the yarn guides and cause yarn unevenness, which lowers the yarn grade from prime to secondary quality.
Regular cleaning of the hackling boards reduces the generation of these knots by removing short and broken flax fibres before they can clump together.
Fabric Defect
Unwanted knots in the finished yarn create visible spots on the surface of the woven linen cloth. When the yarn has a high nep frequency, it causes dyeing inconsistencies because the dense knots absorb less dyestuff than the aligned fibres. Ensuring low nep levels during spinning results in a uniform fabric appearance after finishing.