Yarn Steaming and Heat Setting After Twisting
topic
Twisted synthetic yarn heat setting uses autoclave steam treatment at 110 to 130 degrees Celsius for 20 to 40 minutes to thermally set the twisted yarn configuration in thermoplastic fibres including nylon and polyester, eliminating the tendency for snarling and kinking that unset twisted yarn shows under tension relaxation, with heat setting being essential for producing twist-stable knitting yarns and sewing threads that run reliably through processing equipment.
Role
Stabilises the twist geometry of thermoplastic twisted yarns by setting the helical filament configuration through thermal relaxation above the polymer glass transition temperature, preventing the snarling behaviour of unset twisted yarn that causes processing problems in winding, warping, and knitting operations where yarn snarling causes machine stops, knot formation, and fabric defects that make twist-unset yarn commercially unusable.