A computational approach to evaluate temperature and heat partition in machining with multilayer coated tools

In this paper, analytical models for estimating the interface temperature and heat partition to the chip in continuous dry machining of steels with flat-faced tools treated with multilayer coatings are presented. The database for modeling includes changes in the thermal properties of both workpiece and substrate/coating materials and the Peclet and Fourier numbers occurring at actual interface temperatures. Process outputs involve the average tool-chip interface temperature, the tool-chip contact length, the friction energy and the heat balance between the moving chip and stationary tool. It was found that the heat partition coefficient varies significantly from 0.65 to 0.8 when using multilayer coated tools, and changes from 0.5 to 0.6 for uncoated carbide tools. This implies that the use of multilayer coated tools causes about 30% more heat generated due to friction to be transferred into the moving chip. In general, both power and linear models can be used to estimate the interface temperature.