Precision grinding and facing of copper-beryllium alloys

This paper investigates the machinability of Cu-Be alloys by ultraprecision grinding and facing. The material temper, tool geometry, and machining parameters are varied to assess their effects on surface finish. The study shows that microgrinding of Cu-Be with a diamond wheel generates a rougher surface finish as compared to that produced by microfacing with a single-point diamond tool. Similar chip formation mechanisms are observed when the depths of cut vary from few millimeters to submicron levels. A mathematical model is derived to compare the theoretical and experimental surface finish. Good agreement between predicted and measured data is obtained, providing grain boundaries are visible on a machined surface when being observed under a microscope. Feedrate and tool radius are the most influential parameters on surface finish. Flatness of 20 nm on the 9.5 mm diameter rod and roughness of 2 nm R-a and 8 nm R-t are achieved. Although the material's micromachinability is the same for both the aged and unaged alloys, size and distribution of beryllides must be controlled for better tool life and surface finish. (C) 1999 Elsevier Science Inc. All rights reserved.