The goal in roughing is to cut with the highest possible material removal rate (MRR) while maintaining a good cut everywhere and having a long tool life. It is a high and consistent MRR that causes short roughing time.
Traditional toolpaths follow contours of the pocket geometry using a constant stepover. When the tool encounters an inside corner, the tool's engagement with the material radically and rapidly increases. This greatly increases the load on the tool and the temperature of the tool. Chatter and other undesirable cutting conditions may result. This does not happen with TrueMill. With TrueMill the stepover is varied, if necessary, along the toolpath, depending upon the toolpath radius and in-process material boundary, such that the tool engagement is kept nearly constant. This greatly reduces the variation in tool load, tool temperature and chip thickness allowing for a high and consistent material removal rate.