Quantifying Primary Trim Scrap in Rapier Weft Insertion
Primary rapier trim scrap depends on insertion geometry rather than fabric width, requiring exact tail length modeling to prevent yarn yield deficits.
Leno Selvedge
Edge Binding
Specialized edge structures utilize twisted warp yarns to lock the weft ends securely in shuttleless weaving. The leno selvedge is a narrow, durable border created by pair-wise twisting warp yarns around each inserted weft pick. This technique prevents the weft from fraying or sliding out of the fabric body during subsequent wet processing.
It is highly effective for open-weave and low-density linen fabrics.
Mechanical Setup
Forming twisted yarn structures on high-speed looms requires a specialized shedding mechanism. The leno selvedge is produced using leno healds or a dedicated leno motion device that causes two warp yarns, the ground thread and the crossing thread, to cross over each other between insertions. As the rapier or air-jet inserts the weft, these threads twist around the pick, trapping it in a secure grip.
Because flax yarns are stiff and relatively inelastic, the tension on these leno threads must be carefully managed to prevent yarn breakage. This setup is commonly used on both the left and right sides of the fabric to ensure symmetrical tension and uniform edges.
Processing Advantage
Linen fabrics undergo aggressive washing and bleaching that can cause loose edges to unravel. The leno selvedge provides superior stability compared to standard flat selvedges, making it ideal for fabrics destined for heavy finishing. It allows the fabric to be processed on continuous finishing lines without risk of edge damage.
This reduces waste and ensures a high-quality finished product.