Tool Path Dramatically Increasing Manufacturing Efficiency

By Surfware

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.

The TrueMill toolpath consists of "racetracking" and "D-Slotting". Throughout the entire toolpath, the tool engagement never exceeds the user's specified value. Throughout the section of the path that is racetracking, the tool engagement is kept nearly constant. This is the largest part of the toolpath. Throughout the section of the path that is D-Slotting, the tool engagement varies more, but the variation is much less than with a traditional toolpath.

With a conventional toolpath, the problems caused by the spike in the tool load, tool temperature and chip thickness, are mitigated by a variety of methods, each of which has only limited success. In conventional machining, the MRR is lowered over most of the tool path by making a shallow depth of cut or lowering the feedrate. Lowering the MRR reduces the load on the tool (for a given surface speed). Then when the MRR spikes due to the radical and rapid increase in tool engagement, the load on the tool is not excessive at that point. The obvious disadvantage of this technique is that having a low MRR almost everywhere in order to handle brief, but large spikes, results in a longer roughing time than if a high and consistent MRR were maintained everywhere.