Abstract
Shrinkage of cloth caused by needle penetration in the lock stitch machine sewing had not been measured and thus the characteristics of such shrinkage had not been presented. An investigation of the shrinkage was carried out on several types of cloth under various sewing conditions.
The following results were obtained.
1) When the stitch density is constant, the shrinkage ratio y (%) is related to static needle thread tension x (g), by the expression, y=ax2d+c, where a and c are constants.
2) The 0 g shrinkage ratio, i.e., the shrinkage ratio at the needle thread tension Olgiis useful for the estimation of the shrinkage by needle and sewing thread penetration.
3) At a low stitch density, there is a positive relationship between the stitch density and the 0 g shrinkage ratio.
4) The material and the diameter of sewing thread are factors determining the extent : of the shrinkage.
5) The shrinkage could be predicted by means of stitching cloth without thread.