An Energy Analysis of Electric and Pneumatic Ultra-high Speed Machine Tool Spindles

There is a growing demand for ultra-high speed precision machine tool spindles to create complex miniature devices and features, in consumer markets such as medical devices, electronics and communications. The key enabling drive technologies for spindle rotational speeds in the 100,000 rpm range includes electric motors, both AC and DC powered, and air turbines. In particular for high speed micromachining, turbine spindles have advantages in terms of precision and cost. A widely considered drawback of pneumatic technology though is low energy efficiency, but to date there has been little in depth analysis of commercial/state-of-art turbo-spindle energy performance. This paper provides a holistic comparative analysis of electric motor and turbine powered spindle electrical power requirements, by including the power demand of supporting systems and infrastructure. The analysis indicates that at present the energy usage associated with turbine spindles is significantly higher than electric spindles. However, a number of technically feasible energy efficiency measures are identified for turbine spindles, which would make their energy performance comparable with electro-spindles. The analysis and results will contribute towards an overall life cycle assessment of high speed turbo-spindle technology, and provide impetus to further explore energy optimization approaches and methods.