Abstract
The Direct drive system for a trunnion unit of 5–axis machining center was newly developed. Direct drive motors for A and C–axis control the trunnion unit and the rotary table precisely without any speed reduction gears, and the motor for C–axis can turn the rotary table of 530 mm diameter at speed of 1,000 min–1. The system realizes highly multi tasking performance at one machine by precise machining function as a machining center and turning cut function like a lathe.