Surface Roughness Characterisation and Analysis of the Electron Beam Melting (EBM) Process

Abstract

Electron Beam Melting (EBM) is a metal powder bed fusion (PBF) process in which the heat source is an electron beam. Differently from other metal PBF processes, today, EBM is used for mass production. As-built EBM parts are clearly recognisable by their surface roughness, which is, in some cases, one of the major limitations of the EBM process. The aim of this work is to investigate the effects of the orientation and the slope of the EBM surfaces on the surface roughness. Additionally, the machine repeatability is studied by measuring the roughness of surfaces built at different positions on the start plate. To these aims, a specific artefact was designed. Replicas of the artefact were produced using an Arcam A2X machine and Ti6Al4V powder. Descriptive and inferential statistical methods were applied to investigate whether the surface morphology was affected by process factors. The results show significant differences between the upward and downward surfaces. The upward surfaces appear less rough than the downward ones, for which a lower standard deviation was obtained in the results. The roughness of the upward surfaces is linearly influenced by the sloping angle, while the heat distribution on the cross-section was found to be a key factor in explaining the roughness of the downward surfaces.

Microstructure and Mechanical Performance of Ti–6Al–4V Lattice Structures Manufactured via Electron Beam Melting (EBM): A Review

“…The accuracy of the EBM process is mainly affected by heat transfer [40]. Due to the high working temperature, the shrinkage of the material and the unmelted powder that could be found attached to the part can cause an error of size and dimensions [88]. Especially, for the smaller details and features, as in the case of the lattice structures, this deviation affects the final performance of the structure.…”

Abrasive fluidized bed finishing to improve the fatigue behaviour of Ti6Al4V parts fabricated by electron beam melting

“…In the postheating stage, the same parameters of preheat 1 are used. The standard sets (themes) of process parameters for Ti6Al4V were adopted [27]. In details, themes named Ti6Al4V A2X-PreHeat-50um-5.0.61 and Ti6Al4V A2X-Melt-50um-5.0.61 were used for the preheating/postheating and melting steps respectively, and the relevant process parameters are listed in Table 1.…”

Electron Beam Melting of Ti-6Al-4V Lattice Structures; Correlation between Post Heat Treatment and Mechanical Properties

“…EBM process can avoid the first two defects mentioned above and limit the latter due to its vacuum working conditions [11]. On the other hand, during the production of Ti-6Al-4V alloy via the EBM process due to the presence of preheating phase before the melting, the temperature inside the building chamber reaches values of 650-750°C for this specific alloy [11], [13,14]. These working conditions ensure small thermal shrinkages and the powder bed results in enough strength to support the construction of the overhang part and limiting the use of supports [15].…”