The following are excerpts from a MMS online article that I thought was interesting.
===========================================================================There are four barriers to aggressively milling aluminum: chatter, chips adhering to the tool, the abrasiveness of the material and controlling the large volume of chips. To attack the chatter problem, the flutes of the SharC Mako are not evenly spaced. Rather, the tool has two long flutes and two short flutes. This uneven spacing prevents regular flute impacts from creating harmonic vibration, which can cause chatter in the walls and floors of the cut.
Aluminum?s natural ductility and malleability make it generally easy to work with and attractive for machining. But under aggressive cutting conditions, it becomes gummy, sticking to flutes and causing the ruin of many an end mill. The Toolmex design addresses this problem by decreasing the tool?s surface finish to 15 Ra.
Oxides left in the aluminum from the melting or casting process are a source of abrasiveness in all aluminum grades. In fact, many industrial abrasives contain the same material?aluminum oxide. Cast grades of aluminum can contain aluminum oxides left over from the sand-cast process and can also contain the more aggressive silicon oxide. To combat these abrasives in aluminum parts, the Toolmex design uses TiAlN coating with a high concentration of aluminum oxide to essentially fight fire with fire.
During chip formation, chips tend to curl, taking up more space after they are cut than before. Because the chips tend to stay in the flutes, the chances are high that chips will be cut more than once when using conventional end mills. The Toolmex design is able to address this thanks to the fact is has three flutes instead of four. The odd spacing makes it possible to grind what the company calls ?gash rollout? into the bottom of the end mill. Gash rollout offers extra evacuation area, picking up loose chips from the bottom of the end mill and forcing them out the top. ===========================================================================