Yarn Evenness and Hairiness Testing
topic
Uster Tester 6 (capacitance-based mass variation measurement): CV% (coefficient of variation of linear density, target <1.5% for polyester FDY), Uster thin places (−50% threshold), thick places (+50%), neps (+200%), imperfections index. Uster hairiness (optical, counts fibre ends protruding >1mm — for spun-like DTY). Spectrogram analysis (FFT of mass signal) identifies periodic defects (machine wavelength signatures). Classimat (visual defect classifier): rare large defects that cause fabric defects (classifies by length and weight deviation).
Role
Yarn evenness testing with the Uster Tester is the industry standard quality control methodology for polyester yarns. Statistical parameters (CV%, imperfections) and their correlation with fabric appearance defects (barré, pilling zones) are central to industrial textile quality engineering.