Influence of the chemical composition on the machinability of brasses

Although brasses are essentially copper and zinc alloys, they also contain other alloying elements such as lead, silicon, aluminium, iron, tin, manganese, nickel or arsenic whose presence and content are responsible for the wide variety of properties inherent to these materials. In this article, the effect of the chemical composition of brasses, considering each alloying element and the effective copper content, upon the machinability has been investigated. For that purpose, machinability tests have been carried out on a CNC lathe under lubricated conditions. The study includes both commercial alloys and samples prepared in laboratory. The experimental procedure consists on turning operations, during which cutting forces and surface roughness obtained in brass workpieces are measured. The chip class is accordingly evaluated. The statistic treatment of the results enables the establishment of correlations between the studied machinability parameters and the chemical composition of different kinds of brasses.