Filament Yarn Entanglement and Cohesion Testing

Filament yarn entanglement (interlacing, cohesion) testing measures the frequency and strength of air-entanglement nodes formed by interlacing nozzle treatment (6–8 bar air pressure, slot nozzle) that replace twist as the cohesive mechanism in flat filament and DTY yarns for weaving and knitting processability. Entanglement count (nodes per metre): Rothschild F-Meter (hook probe at 1 cN/dtex running tension, node detected as periodic resistance force increase >30% above baseline, electronic counter): weaving flat filament optimum 40–80 nodes/m (low interlacing preserves filament separation for sizing and shed formation); knitting DTY 20–40 nodes/m; non-interlaced POY 0–5 nodes/m (requires size or twist before weaving). Node breaking force (Rothschild F-Meter with load cell, measures force to pull node apart): 10–25 cN/node for normal weaving interlacing; >40 cN/node for high-cohesion BCF carpet yarn; <5 cN/node indicates insufficient air pressure or nozzle wear — low node strength causes filament separation and snagging on loom heddles. CV% of entanglement spacing (coefficient of variation of node-to-node distance, Rothschild F-Meter statistics per 200 nodes): CV% <25% for uniform interlacing; CV% >40% indicates air supply pressure pulsation, nozzle blockage, or yarn tension variation in texturing machine. Interlacing nozzle geometry effect: slot nozzle (produces open nodes, 30–50 nodes/m) versus tandem nozzle (tight dense nodes, 80–150 nodes/m, BCF carpet application) versus bicomponent interlacing (air temperature 140°C, thermal bonding nodes for high-strength sewing thread cohesion). Crimp take-up uniformity (evenness of DTY crimp density along length) quantified by optical sensor on Uster Tester 6 optical module — CV% of crimp density >5% causes barré defect in warp knitting.