Influence factors and prediction model of surface roughness in single-point diamond turning of polycrystalline soft metal

Abstract

Ultrasmooth surface of soft metals is required in the field of advanced technology. However, the strong plasticity of soft metals makes it hard to achieve high surface finishing in ultraprecision machining. In this paper, the ultraprecision machining experiments of polycrystalline tin are carried out, and the factors including tool nose radius, cutting parameters, and material properties affecting the surface roughness in single-point diamond turning are investigated. Side flow, anisotropy, and grain boundary step are identified as the main causes of increasing of surface roughness, with grain boundary step demonstrating the largest impact. A surface roughness prediction model of tin in single-point diamond turning is established, which takes the minimum undeformed chip thickness, side flow, anisotropy and grain boundary step into consideration. The experiments show that the maximum prediction error of this prediction model is 6.51%.