Mechanical Impact
Rapid deceleration mechanisms in shuttleless looms bring the weft inserter or rapier head to a complete stop at the end of every pick cycle. Sudden mechanical deceleration creates terminal braking shock that transmits high peak tensile stress through the inserted linen weft yarn. Loom machine logs and mill maintenance records track braking forces to prevent yarn snapping and loom stoppage during high-speed production runs.
This kinetic force acts strictly on the weft yarn during insertion deceleration and excludes general warp tension forces.
Weft Tension
Linen yarn exhibits low elasticity compared to synthetic or cotton strands, making it susceptible to tensile failure when subjected to abrupt mechanical stopping forces. Experiencing severe terminal braking shock causes the weft yarn to snap near the receiving selvedge, generating short pick defects or total loom stoppage that requires operator intervention. Modern rapier looms incorporate electronic weft brakes and programmable braking profiles that decelerate the yarn gradually before the pick is released.
Loom technicians calibrate brake timing against weft yarn count and tensile strength specifications, logging settings on loom setup sheets. Optimizing these deceleration curves reduces peak tension spikes, allowing mills to operate looms at higher speeds without causing fabric selvedge defects or yarn breakage.
Machine Boundary
Incorrect brake profile settings cause loop formation or loose pick defects if deceleration occurs too slowly. Excessive braking force snaps weak yarn strands instantly, leaving broken weft ends inside the fabric shed.
