End mill for machining aluminum material
Aluminum is one of the most commonly machined materials, as most forms of the material feature excellent machinability, and is thus a commonly used material in manufacturing. Because of this, the competition for aluminum machining can be intense. Understanding the basics behind tool selection, running parameters, and advanced milling techniques for aluminum can help machinists earn a competitive advantage.
Rake angle for improving cutting quality and enlarged chip pocket realized high efficiency machining. Furthermore, the special treatment of a cutting edge restricting chattering during machining contributes to the improvement of machined surface quality and the extension of the service life.
Requirements for Efficient Machining of Aluminum
Due to the soft and “sticky” nature of aluminum, specific geometries and characteristics of a carbide end mill are required for efficient machining. Many cutting tool manufacturers offer end mills specifically designed for aluminum for this reason.
A sharp edge and high rake angles are needed to separate a chip from the parent material. Positive rake angles up to 25 degrees radial and 20 degrees axial are common.
A high helix angle, generally around 45 degrees is also desirable. The helix helps move chips up and out of the cutting zone and also generates an excellent surface finish. The angle also helps soften the impact at entrance of cut, resulting in a smoother, quieter cut.
For aluminum milling a two- or three-flute end mill works best because this allows for larger flute areas. A core diameter of slightly less than 50 percent of cutter diameter is optimum for the same reason. An open flute design is essential for easy chip movement away from the cutting zone. Surface finish on the flute is also critical. Long-chipping, low silicon aluminum alloys have a tendency to stick to cutting tools. As a heated chip flows over the flute it will try to adhere to the tool surface. The flute surface must be very smooth to counteract this tendency.
Extremely slick commercial tool coatings are also available that reduce the friction coefficient on the flute surface. A good example is one that has a friction coefficient of 0.1, less than half that of TiCN.