Research into mirror surface finishing by the ironing process

Abstract

The object of this paper is to clarify the mechanism of mirror surface finishing by the ironing process. The mirror surface is in demand for electro-optical parts such as optical drums and magnetic discs, which hitherto have been finished by diamond bite cutting, lapping, etc. In the ironing process, the metal surface on the die side becomes a rubbed surface ( Ra = 0.05 μ m for high-viscosity oil) which is markedly inferior to the die surface ( Ra = 0.006−0.011 μ m ); when oils of lower viscosity are used galling often occurs. The metal surface on the punch side becomes a near replica of the punch surface, the degree of replication increasing with larger reductions and lower viscosity oils or when the ironing is carried out dry. In these experiments, the metal surface was finished to Ra = 0.004 μ m under the following conditions: dry on the punch side; high-viscosity oil on the die side; and 50% reduction.