Design and validation of a suction device to reduce cross-contamination in multi-material laser-based powder bed fusion

Powder suction modules for additive manufacturing systems in the field of multi-material laser powder bed fusion (PBF-LB/M) have a critical influence on the quality of the manufactured components. In particular, metal powder cross-contamination originating from insufficient removal of foreign particles during multi-material processing can lead to undesired changes in material properties. In this paper, a suction device was simulated, designed, and validated to reduce cross-contamination. Requirements and necessary characteristic values of the multi-material PBF-LB/M system, the powder suction module, and the materials used were determined. Furthermore, an iterative simulative method and procedure for the design of suction devices was applied. For this purpose, a flattened bell-shaped geometry with flow-optimized fins was presented. This design led to both a high flow velocity and a homogenous velocity distribution at the nozzle inlet for full-surface multi-material PBF-LB/M suction modules. The developed method was validated by applying it to the material combination of tool steel 1.2709 and copper alloy CW106C. The aim was to reduce the cross-contamination generated during the in-process on an SLM 280HL multi-material PBF-LB/M system. Multi-material samples were built using the original nozzle design as well as the newly developed improved powder suction module and investigated in terms of resulting cross-contamination using energy-dispersive X-ray spectroscopy. The improved suction module had a significantly higher flow velocity and a more homogenous velocity distribution at the nozzle inlet compared to the original suction module. Cross-contamination of the manufactured multi-material samples was reduced by up to 93 % due to the improved suction model.