Linear motor for ejector mechanism

Ejector mechanism actuators in electric injection molding machines require large thrust and low operating rate. Although the ordinary linear synchronous motor (LSM) is unfit for this machine, the linear motor presented in this paper is suitable for such use as it is compact in size and cost effective compared to LSM. This paper contains the new linear motor that can generate large thrusts for a short time: its mechanical design, simulated flux profile and experimental results of motor size and thrust output relationship are presented. The described linear motor has an approximate volume of 250 mm × 250 mm × 250 mm and generates a maximum thrust of about 20 kN at a current of 250 A.