Development of a PC-Based Millimeter Scale CNC Turning Centre With Gear Hobbing Capability

Currently, a trend of extreme product miniaturization is particularly evident in sectors such as portable multimedia devices, communications, aerospace and biomedical devices. With increasing product compactness, the demand for precision miniature components is driven higher and higher and the ability to manufacture these components accurately, swiftly and cost effectively is critical for manufacturers to maintain market competitiveness. However, traditional machine tools become ineffective for cutting miniature components. This paper presents our efforts in developing a PC-based millimeter scale turning centre (referred to as MMT hereafter) with gear hobbing capability to machine miniature gears. The system architecture of our 2^nd-gerneration MMT is given. In order to fine-tune the micro gear hobbing process to maximize the gear profile accuracy, the mechanics of the process must be thoroughly understood. In order to do so, a computer simulation tool is developed. The simulation procedure and simulation with different process defects are discussed in detail. 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 0.3mm.