Cutting Temperatures in End Milling of Compacted Graphite Irons

Abstract

With the increasing demand for greater fuel efficiency, automotive companies urge to develop new and more efficient engines. In order to withstand the high compression rates and temperatures at which these super engines are subjected to, vermicular cast iron or compacted graphite iron (CGI) has been identified as the most suitable material to replace gray cast iron (LCI) in the production of engine blocks and cylinder heads. However, compacted graphite iron needs different machining conditions when compared to gray cast iron, therefore studies of the various output parameters involved in the machining of this material are important. This paper studies the influence of the cutting conditions (cutting speed and feed rate) on the average machining temperature near to the cutting zone using an infrared thermal camera in the end milling process of high strength CGIs. The surface roughness and power consumption were also monitored. The results showed that the cutting speed has a greater influence than the feed rate on the average cutting temperature, mainly due to the higher energy provided to the system when the cutting speed is increased. The increase in the feed rate generates more heat and greater temperature variability in the cutting zone, since the thicker chip sizes have more influence in the heat dissipation from the cutting zone. It is also observed that the material characteristics had more influence in the temperature of the regions near to the cutting zone than the machining parameters.