A Study on Efficiency Analysis of Micro Manufacturing Systems

Demands for various miniature mechanical products are increasing. On the other hand, manufacturing systems for those products are becoming larger and more complicated. AIST developed the first prototype of a "microfactory" having practical capability of machining, in 1999, as a counter measure for the situation. It consisted of miniature machine tools and robot manipulators. Since the microfactory was a space-saving and energy-saving system, we proposed that the microfactory could reduce environmental impact of micro mechanical fabrication. However, the effect of the microfactory in reducing environmental impact and costs has not been quantified. An appropriate index to evaluate microfactories by considering environmental impacts, costs and system throughput, simultaneously, will help the concept to become more popular. In this report the authors propose a system efficiency index, based on process time, machine cost, operator's cost and environmental impact, using the microfactory as an example. The calculation shows that the proposed efficiency index is useful in evaluating and designing the system configuration. Comparison with a conventional system indicates that microfactories are hopeful as environmentally conscious manufacturing systems for micro mechanical fabrication.