Needle Deflection and Sewability on Lockstitch Sewing Machine

It is established that in sewing operation, a needle could be deflected by factor such as sewn fabric structure. Empirically, however, this deflection is considered to be closely related to sewability, but without defining the proper correlation they may have. A series of studies are, therefore, undertaken to find out the correlation between sewabiliity and needle deflection in sewing operation. The present paper is aimed at a proposed method for evaluating the needle deflection. In the method, the deflect-ing force is measured by two gauges attached to the lateral surfaces of a needle shank, and then the deflection is estimated by using a simple needle model. Some model studies are carried out on synthetic paper and cotton fabrics, and their results are presented,