Post processing of additively manufactured parts using electrochemical jet machining

Abstract

Additive manufacturing is an increasingly important counterpart to subtractive and constant volume manufacturing methods, however metal powder bed fusion methods often suffer from poor surface quality dominated by adhered unfused powder at the near-surface. Finishing steps are often required before part use in many applications, for example in aerospace components or biomedical implants, where ‘better than cast’ surfaces are sought. Here, we introduce electrochemical jet machining as a single-step process to i) selectively finish additively manufactured parts created by powder bed fusion, and ii) to subsequently micro-pattern these with the intention of increasing part functionality. Roughness of Ti-6Al-4V parts is shown to be reduced from an average Sq of 18.6 µm (as-built), to 2.4 µm upon rapid finishing, and the mechanisms of material removal are explored. Furthermore, repeating micro-dot patterns have been added to demonstrate the potential of the technique to allow tolerance superposition of additively manufactured parts.