Powder characteristics and chemical composition is critical in ensuring repeatable process and suitable mechanical properties of metal components built using AM. One of the major advantages of SLM and EBM is the reusability of the powder. However, few studies have been carried out to assess how recycling particles after high power machining affect the components properties. Let's have a look at preliminary studies. The powder properties (size distribution, shape, composition) significantly affects its processing behaviour and the final qualities of components built using AM techniques. The powder outside the localised melting area can be recycled. This contributes to economic viability and sustainability of these technologies. To ensure reliable and repeatable production, it is necessary to assess and control/limit variation in powder stock properties. The first step is to understand how high power and high-temperature AM processes affect the recycled powder characteristics. We sum up the changes occurring in Ti64 and IN718 powders used and recycled during Electron Beam Melting and Following Selective Laser Melting respectively: Following Electron Beam Melting of Ti6Al4V powder (recycled only) [1]:
Following Electron Beam Melting of Ti6Al4V powder (recycled +5%new) [2]:
Following Selective Laser Melting (EOS M270) of IN718 powder (recycled +5%new) [2]:
Key takeaways Machining has a clear impact on powder. Vaporisation of low melting temperature compounds occurs but their quantities tend to remain within aerospace standards. Higher pressure in the build chamber seems effective in preventing such vaporisation. Ultimately and most importantly, oxygen pick up (hence powder susceptibility to oxidation?) seems to be the limiting factor for powder recyclability in both SLM and EBM. More systematic reviews are needed to verify these trends and predict specific numbers of cycles.
References
[1] V. P. R. Niñerola, “Powder recyclability in Electron Beam Melting for aeronautical use,” Aircr. Eng. Aerosp. Technol., vol. 87, no. 2, 2015. [2] a. Strondl, O. Lyckfeldt, H. Brodin, and U. Ackelid, “Characterization and Control of Powder Properties for Additive Manufacturing,” Jom, 2015. Comments are closed.
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