Additive manufacturing (AM) offers new possibilities in manufacturing and designing products. The aerospace and automotive industries are main drivers because of the possibility of manufacturing lighter structures that reduce weight and save fuel. During the manufacturing process, different discontinuities or defects can occur, depending on the applied AM technology. To ensure constant manufacturing quality of the parts, regular sampling or 100% inspection using nondestructive testing (NDT) techniques is required. In particular, computed tomography (CT) allows a contactless investigation and includes different analysis techniques (such as nominal-actual comparison, porosity analysis, wall thickness analysis, and so on). As an advantage to other techniques, it can even evaluate parts with a very complex inner structure. The following article gives an overview of the AM technology, particularly selective laser melting (SLM), and commonly occurring discontinuities and their possible causes. Furthermore, the functionality of a CT system and the reconstruction process will be explained. In Part 2, we will show a few examples of AM parts under different types of analysis. The limits of this NDT technique will be discussed as well.
ASTM, 2011, ASTM E1441-1: Standard Guide for Computed Tomography (CT) Imaging, ASTM International, West Conshohocken, PA.
ASTM, 2015, ISO/ASTM 52900: Standard Terminology for Additive manufacturing – General principles – Terminology, ASTM International, West Conshohocken, PA.
Carter, L.N., C. Martin, P.J. Withers, and M.M. Attallah, 2014, “The Influence of the Laser Scan Strategy on Grain Structure and Cracking Behaviour in SLM Powder-Bed fabricated Nickel Superalloy,” Journal of Alloys and Compounds, Vol. 615, pp. 338–347.
Dantzig, J.A., and M. Rappaz, 2017, Solidification, second edition, EPFL Press, Lausanne, Switzerland.
Gaytan, S.M., L.E. Murr, F. Medina, E. Martinez, M.I. Lopez, and R.B. Wicker, 2008, “Advanced Metal Powder based Manufacturing of Complex Components by Electron Beam Melting,” Materials Technology, Vol. 24, No. 3, pp. 180–190.
Gustafson, R., 2002, “Prototyping Process Produces Sand Molds, Cores for Production Castings,” Modern Casting, Vol. 92, No. 8, pp. 38–39.
Hassen, A.A., and M.M. Kirka, 2018, “Additive Manufacturing: The Rise of a Technology and the Need for Quality Control and Inspection Techniques,” Materials Evaluation, Vol. 76, No. 4, pp. 439–453.
Kruth, J.P., 1991, “Material Incress Manufacturing by Rapid Prototyping Techniques,” CIRP Annals, Vol. 40, No. 2, pp. 603–614.
Rapid Prototyping Services Canada, 2018, http://rapidprototypingservicescanada.com/selective-laser-sintering-sls.php, accessed 20 July 2018.
Wong, K.V., and A. Hernandez, 2012, “A Review of Additive Manufacturing,” ISRN Mechanical Engineering, Vol. 2012, Article ID 208760, https://doi.org/10.5402/2012/208760.
192 Page Views
0 PDF Downloads
0 Facebook Shares