Filament Yarn Quality Control

Quality parameters: linear density/denier (measured via wrap reel and weighing, tolerance ±2-3%), tenacity and elongation (tensile testing ASTM D2256, batch testing), boiling water shrinkage (dimensional stability, <5-8% for most apparel), dye uniformity (visual and spectrophotometric evaluation after dyeing, critical for automotive, apparel), and filament uniformity (diameter variation <3% CV, critical for technical textiles). Online monitoring: laser diameter measurement (continuous monitoring of individual filaments during spinning), tension monitoring (detecting breaks, excessive variation), and slub detection (capacitance or optical sensors). Process control: polymer viscosity (IV intrinsic viscosity monitoring via offline GPC, target ±0.02 dL/g), spinning temperature (±1-2°C control critical), quench air temperature/velocity (±1°C, ±5% critical for uniformity), and moisture control (avoiding hydrolysis in polyester, maintaining nylon moisture for processability).