Geometric approaches to enhancing edge quality in planar milling

Abstract

Experimental studies show that the in-plane exit angle is a crucial factor affecting edge quality in milling operations. Serious edge defects start to form at tool exits with an exit angle larger than a threshold value determined by the depth of cut, feed rate and material ductility, regardless of other cutting parameters. By adjusting the tool path, the exit angle can be used as a handle for changing the defect formation on the machined edges. A computational framework that minimizes the primary edge defect in planar milling by appropriate selection of the orientation for parallel tool paths is presented. Algorithms are developed to predict defect locations on linear and circular edges while the tool is moving along a given tool path. Process-planning software implemented with these algorithms demonstrates the feasibility of enhancing edge quality with geometric approaches in an automatic manner. The paper provides an effective solution to the edge defect problem in circumstances such as micro-milling and precision manufacturing where edge finishing is difficult to perform.