Research on different cooling methods in the machining of CGI and GCI

Abstract

Gray cast iron (GCI) is the most common material used in diesel engine blocks. Compacted graphite iron (CGI) is a new material for high-power diesel engine blocks, which can allow an increase in the cylinder-pressures and achieve better fuel economy and a higher power output. However, the difficult machinability of CGI seriously hinders its large scale production. At high-speed machining, the tool life of machining GCI is 10–20 times that of GCI. To improve the tool life of machining CGI, this work focuses on the influence of uncooled, cutting fluid cooled and liquid nitrogen (LN2) cooled methods in the machining of CGI and GCI. The results indicate that LN2 cooled method can effectively reduce the highest temperature and temperature diffusion in the processing. Furthermore, for machining CGI, LN2 cooled method increases the tool life by 192.6% and 66.7% compared with uncooled and cutting fluid cooled methods, respectively. However, for machining GCI, LN2 cooled method plays a negative role. For CGI and GCI, the wear modes of the tools are similar, which are mainly material adhesion, coating wear and adhesion and built-up edge.