A Numerical Model for Heat Transfer in Dry and Wet Grinding Based on the Finite Difference Method and Jet Cooling

Abstract

Grinding is a promising machining method for finishing workpieces that need a smooth surface with tight tolerances. Due to the high thermal energy generated in the grinding zone, an accurate prediction of workpiece temperature plays a crucial role in the design and optimization of the grinding process. Finite difference method (FDM) is used for simulating the temperature distribution in a workpiece subjected to shallow grinding using a DuFort–Frankel explicit scheme. Moreover, two simple methods, one for modeling the effect of material removal in shallow grinding and the other for calculating the heat partition, are presented. A semi-empirical correlation of cooling jet is applied to calculate the convection heat transfer coefficient (CHTC) over the grinding surface. Experiments were carried out to verify the simulation results, and a good agreement was observed between the simulation and experimental data. An analysis of the results indicated that the misestimation of workpiece temperature could occur when the effect of the material removal rate is not considered in the simulation. The simulation results showed that the heat flux flow is one-dimensional for a high Peclet number, while a two-dimensional heat flux flow prevails for a low Peclet number. The results revealed that reducing the Peclet number and extending the depth of cut increase the heat partition. The study of wet grinding demonstrated that, for efficient cooling, the coolant should be applied directly to the contact zone. Moreover, using water-based emulsion as a coolant was more effective than palm and sunflower oils.