Influence of Selected Machine and Material Parameters on the Stitch Length and Its Irregularity

One of the main demands for sewing garment quality is good-looking seams, the appearance of which is greatly influenced by the stability of stitch length. The method and equipment for measuring stitch length in the seam are presented. The article reveals the influence of fabric tensile stiffness, friction force, and sewing speed upon the stability of stitch length. Experimental results evidently prove that the mean stitch length decreases and the stitch length variance increases as the fabric tensile stress grows. However, the mean stitch length increases and the stitch length variance tends to decrease as the fabric external friction grows. The rotational speed of the main shaft also has a great influence on the process. The increase in the rotational speed of the main shaft increases both the mean stitch length and the stitch length variance. Thus, in order to obtain good-looking seams it is very important to evaluate the forces acting in the sewing process, sewing speed, etc.