Melt Spinning Process

Melt spinning for polyester, nylon, polypropylene: (1) polymer preparation—drying (polyester to <50 ppm moisture), melting (polyester 260-290°C, nylon 260-280°C, PP 220-260°C), filtration (removing gel particles, contaminants), (2) metering—gear pump delivering polymer at constant rate to spinneret, (3) extrusion—spinneret with 50-2000 capillaries (0.2-0.5 mm diameter, 2-5× length-to-diameter ratio) forming filaments, (4) quenching—cross-flow or radial air (15-25°C) cooling filaments to below Tg rapidly (quench length 1-3 m), (5) finish application—spin finish (0.5-1.5% emulsion providing lubrication, antistatic, cohesion), (6) winding—godets and winder at 1,000-6,000 m/min creating packages 5-20 kg. Spin-draw process: integrated spinning-drawing (one-step) at 3,000-6,000 m/min for POY (Partially Oriented Yarn) or FOY (Fully Oriented Yarn).