Turning, milling, boring, sawing, and other traditional machining operations are easily performed on machine aluminum and machine aluminum alloys. Many of the same machines that can be used on steel can be used on machine aluminum as well. But to reach optimal machining aluminum conditions including rotational speeds and feed rates, one needs machines specifically designed for machine aluminum alloys.
When working with machine aluminum, one should be aware of its properties in order to work more efficiently and safely.
Machine aluminum’s density allows high speed rotation and translation as its swarf is less than that of steel. Its modulus of elasticity, a third of that of steel’s, needs appropriate chucking and clamping arrangements to avoid deformation and distortion. The machine aluminum’s thermal conductivity assists with heat dissipation.
Also, due to the high rate of chip removal, the heat generated by the machining process gets taken away with the swarf without having had time to diffuse into the metal. A coefficient of linear expansion that’s twice the size of steel makes heating undesirable if criteria of dimensional stability are to be satisfactory. Here, machine aluminum differs from steel because it has no need to provide heat treatment of the “stress-free annealing” kind during machining.
In addition, note that the cutting force required for machine aluminum is much less than that for steel. For the same section of swarf, the force for machine aluminum is one third of that required for low carbon steel. So following for the same cutting force chip removal is three times higher with machine aluminum whose level of mechanical properties are on par with that of low-carbon steel.
It is important to keep in mind that the tools utilized with machine aluminum must have a specific geometry. Very keen edges are required and cutting tool faces must be highly polished. This removes swarf effectively and prevents it from bonding to the cut tool. Cutting angle depends upon the specific machine aluminum alloys. The cutting edge’s rake angle must be greater than six degrees and can attain up to twelve.
When using machine aluminum alloys with less than seven percent of silicon, it is preferable to use cutting tools tipped with TiN,TiCN or DLC coating by PVD deposition.
Like other wrought alloys, machine aluminum can be machined rapidly. Special machines with high speed spindles can exceed 3000 m/min with 2000 and 7000 series alloys. With such high cutting rates, it is possible to achieve thin sheets and lighter components.
Due to machine aluminum’s low modulus, high rates of advance are not advisable even for rough machining. A finishing operation’s rate of advance is determined by the specified surface roughness for the finished product. Cut depth depends on specified accuracy.
During machining aluminum, lubrication has three very important functions. It cools the machine aluminum to dissipate the heat generated by the cutting process, prevents swarf from bonding to the cut tool, and it removes swarf from the point of machining.
For these reasons and more, machine aluminum is a more pliable and beneficial metal to machine than steel.
