Machining aluminum castings

Machining of aluminum

Generally, cast aluminum alloy parts are easy to machine., including, all types of machining. Low cutting force allows large volumes of metal to be removed in one pass. The surface quality after machining depends on the processing parameters, such as cutting speed, cutting geometry, lubrication and cooling.

More speed – less roughness

When machining aluminum, it is recommended to use high cutting speeds so that, to achieve the lowest possible roughness of the processed surface, all other things being equal.

Effect of silicon on cutting tool wear

In addition to the microstructure - defects, then, inclusions - the silicon content has the greatest influence on the wear of the cutting tool. So, cutting tool for processing modified hypoeutectic silumin has the highest service life, whereas hypereutectic silumins for the manufacture of cylinders of internal combustion engines cause very significant wear on the cutting tool.

Chips during mechanical processing of silumins

When machining softer aluminum cast alloys, in particular, most hypoeutectic silumins, narrow spiral or short brittle chips are formed. For this, suitable cooling emulsions and lubricants are widely used..

During mechanical processing of hypereutectic silumins, small chips are formed with the formation of powdered silicon. In combination with a lubricant, this powder acts as an abrasive. In a manner, machining of these types of cast alloys is similar to machining gray iron castings.

When machining parts made of eutectic silumins, which are characterized by a very soft matrix, long spiral chips are formed. Moreover, relatively high plasticity of the material leads to adhesion of aluminum to the cutting edges of the tool. These phenomena require the use of a lubricant, what, in turn, leads to a deterioration in the quality of the processed surface.

Cutting tools for aluminum

Cutting tools made of high-speed steels are used for machining aluminum castings., hard alloys and ceramics. Diamond tools are often used for finishing..

See. Aluminum cutting tool

Allowances for machining castings

The machining allowances for the main methods of casting aluminum alloys are used as follows:

  • sand casting: 1,5-3,0 mm;
  • die casting: 0,7-1,5 mm;
  • injection molding: 0,3-0,5 mm.

aluminum shavings

See. also about shavings Machining of aluminum

To minimize aluminum losses during chip remelting, it is sorted by type of alloy and pressed into briquettes. Moreover, the chips must be protected from moisture contamination, greases and iron impurities, so all this significantly reduces the value of aluminum scrap. Aluminum shavings are not a fire hazardous material and do not require fire prevention measures. When grinding aluminum parts, the system for collecting aluminum dust must be explosion-proof.

A source: Aleris International, 2014