MECHANISM OF NEP FORMATION IN AIR-JET TEXTURING

Experiments conducted to investigate the reasons for nep formation in air-jet texturing indicate that neither periodic tension variations in feeder yarn nor differences in tension levels between the two parallel fed ends have any significant effect on nep formation. Insufficient and inhomogeneous opening of filaments inside the nozzle is primarily responsible for nep formation; higher levels of interfilament friction and lower vortexing intensity contribute to insufficient opening of the filament bundle. We therefore suggest that neps in air-jet textured yarns are formed because the filament bundle does not open in the nozzle. Partial opening results in one kind of nep, while complete lack of opening causes another kind in the succeeding part of the unopened section of the yam.