Crankshaft miller is a machine tool used to mill crankshafts for engines. The miller causes a great amount of heat during the cutting process, which combines heavy and intermittent cutting. In this paper, the approximation equation of thermal displacement which applied a method to estimate thermal deformation on the basis of a few machine temperatures and the finite element analysis is proposed. The thermal characteristics and the mechanisms of heat transformation in the crankshaft miller are made clear by numerical simulations using the finite element models of the miller and the experiments. The simulations tried a steady and transient state analyses of heat transformation to consider the heat transfer coefficient in the cutting process. From the results of the analyses, the temperature distribution and thermal deformation on each part of the miller were found. The results of analyses are compared with the experimental values using the actual miller. The point of efficient measuring temperature and the calorific values in order to revise each coefficient value in the approximation equation were examined. Additionally, the effectiveness of proposed approximation equation was shown.
