The Improvement of Machinability of Gray Cast Iron Using Nonmetallic Inclusions in High Speed Cutting (2nd Report)

Abstract

This paper deals with machinability in high-speed face milling of gray cast iron to which small quantities of Al and Mg were added. The machinability of Al-Mg-added gray cast iron was evaluated in face milling with cermet inserts at cutting speed from 100 to 1000 m/min in comparison with conventional gray cast iron and Al-added gray cast iron. In the face milling of conventional gray cast iron and Al-added gray cast iron, the wear increased significantly as the cutting speed increased. The wear pattern of tools in the milling of these irons were almost the same, and the thermal cracks similarly occurred in both cases. On the other hand, the addition of both Al and Mg has drastically decreased the wear rate and the wear hardly progressed even in prolonged cutting length after initial wear. The amount of the adhesion on tool faces increased as the cutting speed increased. The adhered layer mainly consisted of the elements added to the work material. As this result, the increase cutting speed resulted in the thick adhered layer and the reduction of tool wear. Furthermore, the small addition of Al and Mg prevented the thermal cracks in the face milling of the gray cast iron.