Department of Mechanical Engineering Faculty of Engineering, Yazd University, Yazd, Iran


Sewing is one of the most commonly used manufacturing processes in the world. In the textile industry, development of sewing machines with optimal mechanical performance is very important. Obviously, the quality of sewing, the increase of the needle transmission force and the optimal mechanical advantage are greatly dependent on the design criteria of the needle driving mechanism. Unfortunately, despite the importance of this topic, very limited number of researches has been carried out in this regard. Therefore, in this paper, first a newly developed needle driving mechanism of a sewing machine is introduced. Then, the concepts of transmission angle and mechanical advantage are described. Next, the multiobjective constrained optimization process of this mechanism using the genetic algorithm is explained. For this purpose, some objective functions are presented to reduce the needle generated heat by minimizing the needle velocity in the penetration zone, to reduce undesirable vibrations by minimizing the needle jerk, and to increase the mechanical performance by maximizing the mechanical advantage and minimizing deviations of the transmission angle from its ideal value. Results confirm improvement of the required design criteria of the newly developed mechanism in this study