Pulsed mechanical surface treatment—an approach to combine the advantages of shot peening, deep rolling, and machine hammer peening

Abstract

Several manufacturing processes are used to beneficially influence the surface and subsurface properties of manufactured parts. Different aspects such as the surface topography or resulting residual stresses are addressed using different manufacturing processes. This paper presents the first approach for pulsed mechanical surface treatment (PMST), a new manufacturing process aiming to combine the mechanics used in deep rolling and shot or hammer peening. The process can generate a defined surface topography while constantly impinging a mechanical impact on the workpiece. Two different tools (type 1 and type 2) have been designed to approach this new concept. Hardened carbide pins are used for type 1 to prove the concept using a simpler kinematic and resulting in a burnishing-like process. For type 2, hardened roller is used and results in an actual rolling process. Specimens made of S235 are processed in experiments with tool type 1 with varying pulse frequency and feeds. The resulting surface topography is described using optical measurement systems while micro-hardness measurements are used to describe the subsurface properties. The results in general show an increase of hardness in the surface and subsurface layer while the resulting surface topography can be directly controlled by the process parameters and therefore be designed for specific functional properties.