Optimisation of surface determination to improve the accuracy and repeatability of detecting unfused powder in AM Aluminum component
Year: 2019
Type: article
Abstract: Additive manufacturing (AM) is quickly being recognized as a core technology for producing complex and customized components, so the need for well understood non-destructive testing is more urgent than ever. The mechanical properties of cast components are well studied and non-destructive testing is well established by various methods like XCT and ultrasound. On the other hand, there are big challenges for NDT with regard to additive manufactured components as the pores are different in nature from those found in cast alternatives. In additive manufactured components, the pores could be hollow, filled with partially fused powder or unfused powder. Furthermore, porosity could be due lack of fusion of un-melted powder (low laser energy) or balling up effect (too high laser energy). There is also the possibility of unfused powder within the internal architecture of complex components. In such cases XCT becomes an essential detection tool. This paper presents the design of an Aluminum (AlSi10Mg) AM artefact / sample with built-in unfused and semi fused powder features. Several defects with different shapes and dimensions were created. Two 1mm cylinder defects were placed inside an 8mm aluminum cylinder artefact. The first defect was located 200μm from the outside envelope of the surface and the second defect was located centrally 1mm from the top surface of the artefact. The built-in defects were used as markers to identify the determined powder grey value. A Nikon XTH 225 (Nikon Metrology, Tring) industrial XCT was used to analyze the pores/ defects’ location and volume. This threshold was utilized to ascertain the optimum ISO value for surface determination. Data processing, surface determination process and defect analysis was carried out using VG Studio Max 3.1 (Volume Graphics, Heidelberg).The artefact was then sectioned to confirm the actual location and dimensions of the designed defects using an Alicona G4 (Alicona, Graz) focus variation instrument.. The results of the scans were determined using two different surface determination strategies. The results obtained from each of the defect analysis were compared to the designed value and the focus variation. The focus of the study is on providing best practice for selecting inspection parameters, optimizing ISO value for porosity detection and identifying unfused and semi fused powder in AM SLM component.
DOI: 10.58286/23728
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4362238311