THE IMPORTANCE OF INCLUDING SIZE EFFECT WHEN MODELING SLOT MILLING

This paper presents a detailed mechanistic force analysis that include s size effect for slot milling operations. Existing studies of the mil ling process have modeled the slot end milling operation as a simple g eometric extension of peripheral end milling models with constant valu es 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 cuttin g force variation, particularly for steady-state slotting with four-fl ute cutters. It is shown through a comparison of model simulations and experimental results that significantly improved predictions of the c utting force variation are obtained by properly accounting for the siz e effect in slotting. The dependence of the cutting force variation on axial depth of cut and helix angle is demonstrated. Practical implica tions of selecting helix angle and axial depth of cut based on the imp roved slot end milling model are also discussed. Modeling approaches o ther than the mechanistic approach considered here are also noted in t his light.