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A cutting-process model addressing the chip removal and edge ploughing mechanisms separately yet simultaneously is presented. The model is developed such that it is readily applicable in an industrial setting, its coefficients have physical meaning, and it can be calibrated with a concise quantity of orthogonal cutting data. The total cutting and thrust forces are each the summation of its individual components acting on the rake face and clearance face. These components are calculated using the rake and effective clearance angles from the normal and friction forces acting on each of these tool surfaces. These normal and friction forces are calculated by the chip removal and edge ploughing portions of the model, respectively, using four empirical coefficients. To calculate the clearance face forces, the interference volume is required, the calculation of which is based on a geometrical representation of the clearance face interference region. This representation is characterized in part by the depth of tool penetration, which is influenced by thermal energy generation and is therefore determined using a fifth empirical model.

A new machining process model that explicitly includes the effects of the edge hone is presented. A force balance is conducted on the lower boundary of the deformation zone leading to a machining force model. The machining force components are an explicit function of the edge radius and shear angle. An increase in edge radius leads to not only increased ploughing forces but also an increase in the chip formation forces due to an average rake angle effect. Previous attempts at assessing the ploughing components as the force intercept at zero uncut chip thickness, which attribute to the ploughing mechanism all the changes in forces that occur with changes in edge radius, are seen to be erroneous in view of this model. Calculation of shear stress on the lower boundary of the deformation zone using the new machining force model indicates that the apparent size effect when cutting with edge radiused tools is due to deformation below the tool (ploughing) and a larger chip formation component due to a lower shear angle. Increases in specific energy and shear stress are also due to shear strain and strain rate increases. A consistent material behavior model that does not vary with process input conditions like uncut chip thickness, rake angle and edge radius can be developed based on the new model. [S1087-1357(00)01302-2]

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This paper presents a detailed mechanistic force analysis that includes size effect for slot milling operations. Existing studies of the milling process have modeled the slot end milling operation as a simple geometric extension of peripheral end milling models with constant values for the specific energies used to predict forces for a given cutter geometry and cutting conditions. This paper addresses the limitations of this approach for accurate predictions of the instantaneous cutting force variation, particularly for steady-state slotting with four-flute cutters. It is shown through a comparison of model simulations and experimental results that significantly improved predictions of the cutting force variation are obtained by properly accounting for the size effect in slotting. The dependence of the cutting force variation on axial depth of cut and helix angle is demonstrated. Practical implications of selecting helix angle and axial depth of cut based on the improved slot end milling model are also discussed. Modeling approaches other than the mechanistic approach considered here are also noted in this light.