Development of a Millimeter Scale Turning Centre for Gear Hobbing

Conventional machining is generally preferred in manufacturing metal components with 2'/2D features and/or 3D silhouettes. With the ever increasing demand for reduced sizes and increased accuracy, however, traditional machine tools have become ineffective for cutting miniature components. A typical example is gear manufacturing. It is known that gears are machined using the gear hobbing process in which the cutter axis and the workpiece axis are required to be synchronized to an accurate constant ratio. According to a market survey, only a few machine tools can make gears with the size of (01.0 mm. This paper presents our effort in developing a PC-based millimeter scale CNC turning centre with gear hobbing capability to machine miniature gears. In this machine, the synchronization required by the gear hobbing process was achieved directly by controlling the AC servomotors. Experiment results show that the machine is able to machine high quality components with diameter as small as 0.075 mm and hob gears with module as small as 0.09.