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Publication . Article . 2022

Developing processing windows for powder pre-heating in electron beam melting

Zeyu, Lin; Dadbakhsh, Sasan; Rashid, Amir;
Open Access
Published: 01 Nov 2022 Journal: Journal of Manufacturing Processes, volume 83, pages 180-191 (issn: 1526-6125, Copyright policy )
Publisher: Elsevier BV
Country: Sweden
Abstract

Powder pre-heating is a critical step in electron beam melting (EBM), while there has been no systematic work tostudy the corresponding processing windows so far. Accordingly, this work investigates the relation between thesintering and the issues appearing during pre-heating (e.g., smoking or excessive sintering) in EBM of highlysusceptible-to-smoke Nickel-Titanium (NiTi) powder. First, the EB spot size was assessed depending on differentfocus offsets and beam currents from beam tracking experiments on a ceramic-coated stainless steel plate. Af-terwards, the smoke tests were carried out at different focus offsets and beam currents in terms of beam speeds. Itis shown that a smaller EB spot can effectively prevents smoking by enhancing the sintering degree. However,since this high sintering degree can cause strong powder bonding preventing the powder recycling, less focusedbeam (or larger EB spot) was selected to reach medium but efficient sintering in the level of around 30 %.Moreover, due to the influence of the diverging angle on the EB-material interaction, it is found that the negativedefocused EB mitigates the smoke phenomenon compared to the positive defocused EB with a similar spot size.Based on the smoke test results, linked to the sintering degree, the processing windows for pre-heating NiTipowder are developed demonstrating three different modes: smoke-heating, melting-heating and healthy-heating. QC 20220930

Subjects

Industrial and Manufacturing Engineering, Management Science and Operations Research, Strategy and Management, Engineering and Technology, Teknik och teknologier, Production Engineering, Human Work Science and Ergonomics, Produktionsteknik, arbetsvetenskap och ergonomi

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