On-Line Seam Qualification and Control in a Sewing Machine

This paper presents part of the results achieved with the use of a system and electronic equipment on an overlock sewing machine, to acquire, monitor and storage the variations of the thread tensions during the stitch formation. The correct balancing of the stitch, as well as the amount of the overall pre-tension given to the threads are of the highest importance to a quality stitch formation. The system developed allows the establishment of relationships between thread tension on the three threads involved in the stitch formation of stitch type 504 and its consumption and the evaluation of the quality of the seams. The knowledge of the absolute reference values of each variable on different sewing conditions, are the first step for the development of a control device to guarantee the on-line set-up of the sewing machine. Another application of the system used is the possibility to compare on-line the “sewability” of diflerent materials.