Abstract
ADI (austempered ductile iron) has superior mechanical properties and shows a strength nearly identical to that of hardened steel. In view of such advantageous properties of ADI, research has been carried out in order to apply ADI to gears. However, it had long been thought impossible to develop ADI gears, because ADI is a difficult-to-cut material and tool failure occurs in a short time. This study aims at developing a method of hobbing ADI with a hob of high-speed steel. The results obtained are summarized as follows : ( 1 ) A tool of 5° rake angle and 15° relief angle was best, undergoing very little wear of the cutting edge without failure. ( 2 ) The conditions of 1-thread hob, hob feed of 1.0 mm/rev and cutting speed of 63 m/min are suitable for hobbing ADI gears. ( 3 ) The wear obtained with cutting oil was larger than that obtained in dry cutting. ( 4 ) By cooling the cutting portion with compressed air, tool life was improved.
