Chemical etching as a finishing process for electron beam melting (EBM) parts

Abstract

Additive Manufacturing (AM) allows to reduce the industrialization step by eliminating or minimizing the tools conception phase, process development,… These technologies permit now to produce real parts with required mechanical properties. AM technologies allow new ways of thinking by unlocking the design limitations encountered by other manufacturing methods. The Electron Beam Melting (EBM) technology is a powder-bed-metal based additive manufacturing technique developed at Chalmers University of technology in the late 1990’s and commercialized by the Swedish company ARCAM AB in the early 2000’s. The most widely used material for the EBM Process is Ti6Al4V. This is the material used in this study with standard processing parameters. EBM process is a near net shape process and it is necessary to carry out finishing operation after EBM. The goal of this research is to analyze the impact of chemical etching on parts produced by electron beam melting. Given that the surface conditions are poor (Ra between 25 to 35 µm), an enhancement of these is asked. Dimensional and surface measurements were realized on conceived parts. Different exposure times were tested. The impact of these times on surface quality was evaluated. To help predicting the excess thickness to be provided, the dimensional impact of chemical polishing on EBM parts was estimated. 36 parts were measured before and after chemical machining. The improvement of surface quality was also evaluated after each treatment.