The Effects of Copper and Silicon on the Machinability of Copper Silumin

Abstract

Copper and silicon, which are main alloying elements of the so-called copper silumin (JIS AC4B), seem to influence, according to their respective quantities, the mechanical properties, especially the machinability, of the alloy, even within their specified standard ratio of 2.0∼4.0% of copper and 7.0∼10.0% of silicon.In this paper, the effect of adding copper and silicon on the mechanical properties of the alloy are discussed, especially, the machinability in terms of cutting force, finished surface integrity and deposit material, built-up edge, and chip formation in turning test, and also in terms of the drilling resistance, and drilling speed.The test was perfomed on the specimen group 1, which contained about 8% silicon and varying from copper 1 to 5%, and the specimen group 2, which contained about 3% copper and silicon varying from 5 to 12%.The results are summarized as follows:The tensile strength is slightly low and the elongation is considerably greater in the alloys containing less amount of copper, but the elongation decreases and the strengths (Tensile strength, shearing strength, hardness and others) increase with the increased copper content. And the strengths of alloys containing about 8% silicon are superior to those of alloys containing silicon either more or less than 8%. From the cutting tests, no difference is recognized in machinability in the viewpoints of the cutting force, finished surface, built-up edge and others, compared among the different amounts of the alloying elements.In case of 1 to 2% copper content, fused deposits are observed on the surface, and regarding chip formation chips of continuous straight type are produced. When the copper content is more than 2%, however, there seems no difference in those measures by varied copper and silicon contents.