Abstract
The productivity of deep hole drilling is greatly improved in recent years, where the long twist drill with the high pressure coolant supply has been used. The problems of this system are revealed such as the excess consumption of electric power, and the dispose of the large quantities of waste coolant. To solve these problems, MQL drilling becomes practical and now widely used in many Japanese automobile factories. In this research, the process improvement technology for MQL drilling is proposed. Excellent tool life was achieved by using mixed gases as the mist carrier instead of the conventional compressed air. The results of drilling experiment shows the increasing drill-life and the increasing thrust force during drilling. The cutting force and chip thickness analysis suggest the novel tribological conditions derive from atmosphere.
