The feasibility of a new method for scallop removal in die milling

In this paper a new method for die milling, which significantly reduces the volume of the scallops while maintaining the same overall productivity as the conventional operation, is proposed. The method is based on the superposition of an additional motion, termed the tertiary motion, onto the conventional motion, i.e., spindle rotation and feed, of the milling process. This additional motion results in the capability to control the topography of the generated surface and, for suitable combinations of the motion parameters, in a very effective means for scallop removal. The basic theoretical concepts of the approach are summarized addressing the relationship between tool geometry and the kinematics of the operation and the resulting surface topography. Subsequently a method is introduced for the synthesis of three-dimensional surfaces through computer simulations. Simulation results are presented that illustrate the utility and the feasibility of the proposed method for generating surfaces with a wide range of topographical characteristics. Finally, the feasibility of the approach is demonstrated through the development and implementation of a three-axis computer controlled "die finishing attachment" It is shown that more than 90% of the volume of the scallops generated by conventional ball nose milling can be removed.