Abstract
The powder bed-based additive manufacturing (AM) process contains uncertainties in the powder spreading process and powder bed quality, leading to problems in repeatability and quality of the additively manufactured parts. This work focuses on identifying the uncertainty induced by particle size distribution (PSD) on powder flowability and the laser melting process, using Ti6Al4V as a model material. The flowability test results show that the effect of PSDs on flowability is not linear, rather the PSDs near dense packing ratios cause significant reductions in flowability (indicated by the increase in the avalanche angle and break energy of the powders measured by a revolution powder analyzer). The effects of PSDs on the selective laser melting (SLM) process are identified by using in-situ high-speed X-ray imaging to observe the melt pool dynamics during the melting process. The results show that the powder beds made of powders with dense packing ratios exhibit larger build height during laser melting. The effects of PSD with efficient packing on powder flowability and selective laser melting process revealed in this work are important for understanding process uncertainties induced by feedstock powders and for designing mitigation approaches.
Highlights
The powder bed-based additive manufacturing process makes parts through fusing or binding powders in a powder bed [1,2,3,4]
Previous research results have shown that changes from a homogenous powder to non-homogeneous powders result in an overall reduction of powder flowability [18,19]
In-situ high-speed X-ray imaging was used to determine the effects of particle size distribution on selective laser melting dynamics
Summary
The powder bed-based additive manufacturing process makes parts through fusing or binding powders in a powder bed [1,2,3,4]. One cause of non-uniformity of part quality is variation of powder size distribution (PSD). Previous works have investigated the effects of varying powder size distribution on the resulting material properties [1,6,8,9,10,11]. Liu et al conducted work highlighting the effects of isolating two PSDs: a narrow, near-homogenous, PSD and a wider, heterogeneous, PSD with near identical average powder size [20]. Liu’s work concluded that changes to PSD affect powder bed flowability, Materials 2022, 15, 705. The 15–25 μm powder and 35–48 μm were mixed to create four additional particle sizeTdhiest1r5ib–u2t5ioμnms.
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