Examining the effect of lubrication rate on sewing thread friction coefficient and on seam slippage [Ispitivanje utjecaja parafiniranja na koeficijent trenja šivaceg konca i na pomicanje šava]

Sewing thread is one of the most important factors that affect seam quality. For this reason, it is necessary to examine sewing thread in details. The friction force that occurs during the sewing may cause the breaking of sewing thread. These breaks reduce the seam quality and increase the sewing duration. In this study, the effects of different rates of lubrication applied for sewing threads on the coefficient of friction of thread to-thread and thread to-metal for reducing the friction force is examined. Also, the effect of lubrication amount on seam slippage, which is one of the most important seam faults, is investigated. In the study, three different counts of poly/poly sewing thread and five different lubrication amounts are used for each serving thread. In the tests was established that the increasing of the linear density of the sewing thread and the lubrication amount reduce thread- to-thread friction coefficient. The increased lubrication rate reduces thread to-metal friction coefficient, and the changing of the linear density of the sewing thread does not affect the friction coefficient. Beside this, change of lubrication rate has no effect on seam slippage