Critical evaluation of the pulsed selective laser melting process when fabricating Ti64 parts using a range of particle size distributions

Abstract

Selective Laser Melting (SLM) is a metal additive manufacturing process where parts are fabricated from metal powder based on CAD data. Selection of the best process parameters for the pulsed SLM processes is a fundamental problem due to the increased number of parameters that have a direct impact on the melt pool compared to the continuous SLM processes. In previous studies, volumetric energy density or scan speed have been used as control variables for applied energy. In this paper, the process parameters (laser power, exposure time, point distance and hatching distance) were considered individually, in addition to particle size distribution and layer thickness. The Taguchi experimental design method was used to determine and optimise the effect of the selected input parameters. The effect of exposure time and its correlation with layer thickness and particle size distribution was then investigated. The results show the best combination of process parameters which can provide fully or near fully dense parts. The results also show the minimum exposure time that can be used with different powder types and layer thicknesses. The paper concludes with a study which shows the part location has a significant impact on sample quality.