Machinability in Hot Machining

There has been much improvement in the quality of metallic materials. Some materials, however, we still find very difficult to treat. Hot machining by electric current is a method this writer has found quite effective in treating such materials. In this research, cemented carbide tools were used to turn various kinds of metallic materials. As a result of experiments, the writer has come to the following conclusion : (1) Surface roughness of better quality is obtained by running electric current than by usual machining. The more electric current, the better. (2) Surface thus turned is less subject to erosion. (3) As long as heating temperature remains less than 800 deg. C, the tool life remains the same whether electric current is used or not. (4) The forms of chips, affected by electric current, change from shear type to flow type with their surface roughness becoming better in quality.