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.
Catch Selvedge
Edge Reinforcement
Temporary auxiliary borders are woven along the edges of a fabric to secure the weft yarns during high-speed insertion. The catch selvedge holds the weft ends in place until the primary selvedge can be secured by the weaving mechanism. It is later trimmed away from the main body of the fabric as waste before finishing.
This structure prevents the weft yarn from slipping out of the warp tension.
Mechanical Operation
Rapier and air-jet looms rely on continuous tension to prevent the inserted weft from curling or slackening. The catch selvedge is formed by a small group of independent warp yarns that operate at the extreme outer edge of the loom. As the weft carrier exits the main shed, it deposits the weft yarn across these auxiliary yarns, which interlace to form a temporary bond.
This arrangement ensures that the weft remains taut during the beat-up process, preventing loose loops or uneven tension across the fabric width. Once the main weft is bound by the primary weave, the connection is severed by a mechanical blade, leaving the catch selvedge as a strip of waste yarn.
Process Importance
Fine linen weaving requires precise control over yarn tension to maintain a flawless fabric face. Without a stable catch selvedge, the high twist of flax yarns would cause them to recoil and form weft snarls along the edges. The auxiliary edge acts as an anchor, allowing the cutters to trim the weft ends cleanly without disrupting the tension of the active warp ends.
This ensures a clean and stable edge for subsequent wet processing and dyeing.