An analytical grinding force model based on individual grit interaction

Abstract

Abstract Grinding force is an important parameter that affects the productivity and quality of industrial products. The very high negative rake angles of the grits play an important role in the material removal mechanism resulting in the formation of a stagnant area ahead of the grits called the dead metal zone (DMZ). Ploughing force also comes into effect when the undeformed chip thickness is comparable with the cutting edge radius of the active grits. Based on these facts, in this study, a new model is proposed to predict the grinding forces and understand the material removal mechanism. This is achieved by modeling the grit-workpiece micro-interaction and geometry of the grinding wheel, enabling the engaged grits and undeformed chip thickness to be defined. An analytical kinematic-geometrical force model considering dead metal zone and ploughing, as well as practical conditions such as run out and wheel wear has been developed. The input parameters of the model are grinding conditions, workpiece material and wheel properties, and sliding coefficient of friction between wheel-workpiece pair. The grinding force is composed of three portions including ploughing, cutting and formation of DMZ. The influential parameters on each force portion are analyzed. Considering the physical mechanisms involved in the grinding process, the model provides more in-depth knowledge about the grinding forces which can be used for finding the optimum conditions. This model is able to explain some inherent characteristics of grinding forces such as the high ratio of normal to tangential force and high specific grinding energy in low feed rates and depth of cuts. A series of experiments were carried out to evaluate the model accuracy and the contribution of each force portion is discussed in detail. The model predicts the grinding force and its fluctuations accurately without the need for performing grinding calibration tests which is a clear advantage compared to the current models.