Draw Pin and Hot Roll Drawing Systems
topic
Draw winding machines use heated godets or draw pins at defined temperatures of 70 to 90 degrees Celsius for polyester and 50 to 70 degrees Celsius for nylon to heat the yarn above the glass transition temperature before stretching between the first and second roll set at draw ratios of 1.5 to 4.0 depending on the POY orientation level, with drawing at elevated temperature providing the molecular mobility needed for uniform filament extension without cold drawing neck propagation.
Role
Develops the full molecular orientation and crystallinity of synthetic filament yarns through controlled hot drawing that provides the thermal activation for uniform molecular chain extension, with hot draw temperature and draw ratio being the two primary process variables that determine the tenacity, elongation, and thermal shrinkage properties of the fully drawn yarn product for weaving and industrial yarn applications.