Crimp Measurement: Frequency, Amplitude and Contraction
topic
Crimp parameters for polyester staple: crimp frequency (crimps/cm, target 10–18 for cotton system, 4–8 for worsted system), crimp amplitude (height), and crimp contraction (CC%) = (L_crimped − L_extended)/L_extended × 100. Measured under 0.5 mN/dtex tension (BISFA method). Crimp stability: CC% after tensile cycling (measures permanent set). Crimp recovery after boiling (hot crimping stability): critical for polyester/wool blends processed in hot wet conditions.
Role
Crimp parameters determine staple fibre processability in carding and the bulk and handle of the resulting yarn and fabric. Understanding crimp mechanics and its measurement is essential for staple fibre specification and blending design.