Correlation of Yarn Strength with Fiber Strength Measured at Different Gage Lengths

Abstract

The fiber strengths of 105 cottons measured with the Clemson Flat Bundle Tester at 0, 2, 4, 6, and 8 mm. gage length were correlated with the strength of yarns made from the same cottons. The correlation between single end yarn strength and flat bundle fiber strength was higher for all of the longer gage lengths than for so called zero gage length, being highest for 2 and 4 mm. For these gage lengths the coefficients of correlation ranged from 5% to 27% higher than for zero length for the several types and numbers of yarn. The correlations for the skein strength favored the longer gage lengths even more than in the single end breaks, the coefficients ranging from 3% to 49% higher for 2 to 4 mm. gage lengths than for zero length. The results indicate that the increase in correlation with greater gage length, up to 4 mm., is higher the finer the yarns and also higher for combed yarns than for carded yarns. From the tests it seems that the "equivalent gripping distance" on individual fibers in yarn breaks must be approximately 3 mm. and that measuring the fiber strength at the short lengths used in the Pressley test will incorrectly rank certain cottons in relation to their merit in yarns.