Evaluation of techniques to quantify the effectiveness of powder bed fusion residue removal protocols

Abstract

Purpose Powder bed fusion (PBF) additive manufacturing (AM) has facilitated the production of medical devices with intricate geometries and patient-matched features. The medical industry especially has leveraged complex geometries for orthopedic applications. However, these geometries increase the difficulty of manufacturing residue removal. Furthermore, PBF-specific methods for residue removal and quantification have not been developed yet. This study aims to assess the use of a novel challenge assembly to evaluate PBF residue removal protocols. Design/methodology/approach A novel modular PBF challenge assembly was evaluated for its ability to resolve differences in the residue removal techniques. Several metrics were adapted from consensus standards and applied to evaluate their suitability. Though the challenge assembly can incorporate multiple complex geometries and reticulated structures, this study used the test case of regular lattice structures and two generic residue removal protocols (RRPs). Findings The challenge assembly successfully represented increasingly complex residue removal scenarios, showing increasing amounts of residue remaining in parts of increasing density. Simultaneous examination of multiple geometries with different residue removal difficulties can be used to design production processes. Indirect estimates of extracted residue provided some information on residue remaining. However, they were not sufficient to evaluate the part because of the high variability and uncertainty. Additional metrics proved necessary to corroborate the results during a verification phase. A carefully selected panel of metrics could provide adequate information to validate a process. Originality/value This study evaluated and demonstrated a framework to assess RRPs for complex geometries. It showed that the results of single indirect metrics such as extracted residues may provide ambiguous results across a range of parts. PBF-specific metrics for residue removal and quantification would greatly improve repeatability and certainty.