Abstract: According to the characteristics of hard-twist yarns, such as high strength, less hairiness, good wear resistance but easy skein twisting and breakage, this paper formulates different sizing formulas and sizing processes, tests and analyzes the sizing quality indexes such as breaking strength, hairiness, wear resistance and end breakage rate, and finally determines the sizing process suitable for hard-twist yarn, so as to improve the sizing quality.

Key words: hard-twist yarns; sizing formulas; twist run back