The Anatomy Of An End Mill For Aluminum
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. Cutting tool manufacturer says all of these challenges can be addressed with the right tool design. The company’s end mill (part of its line) is an example of a tool designed specifically for high metal removal rates in aluminum. Different aspects of the tool were engineered for the separate difficulties of machining aluminum quickly.
To attack the chatter problem, the flutes 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. One typical practice to keep this from happening is increasing the concentration of the coolant or switching from water-soluble coolants to oil-based solvents. The manufacturer design addresses this problem by decreasing the tool’s surface finish to 15 Ra. This requires extra finish passes when grinding, but results in a tool that can avoid sticky aluminum chips using common coolants and concentrations, the company says.