SUMMARY

Accumulated distortion in scenarios where the substrate is an integral part of the final design, such as repair of tooling, can lead to part disqualification. In the present study, use of a new approach to sacrificial supports for additive manufacturing were investigated to mitigate transient thermal induced distortion of thin substrates in a powder based directed energy deposition process utilizing a five-axis hybrid machine tool. In the study, sacrificial supports were deposited on the underside surface of a substrate prior to clad surface deposition. A range of support structure geometries were produced to investigate the impact of these structures on substrate distortion. Substrate distortion was found to decrease with increasing number of supports and support build height. Sacrificial support structures were shown to reduce maximum substrate distortion by up to 87%. Clad surface deposition saw up to a 25% increase in powder catchment efficiency with use of sacrificial supports. Finite element models were used to evaluate sacrificial support structure placement relative to clad surface deposition. Placement of sacrificial support structures withing the bounds of clad surface deposition yielded less distortion than supports placed outside of the clad surface deposition. The present results show that sacrificial supports can be implemented to significantly reduce substrate distortion and could be used as a mechanism to regulate substrate distortion to achieve final dimensional accuracy.