Machining tactics for interior corners of pockets

Abstract

The cutter-workpiece contact of an end mill fluctuates when cutting along a curvilinear tool path. It increases sharply when reaching a concave corner. Since conventional contour-parallel tool-path cutting does not take this condition into account, it will cause a momentarily rise of cutting resistance in concave corner regions, producing undesirable effects such as machine chatter, gouging and even cutter breakage. This paper proposes to use machining tactics in which a corner-looping tool path is employed to remorse progressively the concentrated material at corner regions, thereby restricting the cutting resistance to an acceptable level. Different corner types are categorised and the procedures of generating the proposed machining tactics are described. Experimental results demonstrate that using the proposed machining tactics can significantly control and reduce the cutting resistance fluctuation encountered in concave corner regions.