Design against distortion for additive manufacturing

This paper presents the methodology and findings of a novel piece of research with the purpose of understanding and mitigating distortion caused by the combined processes of additive manufacturing (AM) and post machining to final specifications. The research work started with the AM building of a stainless steel 316 L industrial impeller that was then machined by removing around 0.5 mm from certain surfaces of the impeller’s blades and hub. Distortion and residual stresses were experimentally measured.

The manufacture of the impeller by AM and then machining was numerically simulated by applying the finite element (FE) method. Distortion and residual stresses were simulated and validated. The FE distortion was then used in a numerical procedure to reverse distortion directions in order to produce a new impeller with mitigated distortion. The results have shown that distortions in the new impeller, on average, have reduced to less than 50% of the original non-compensated values.