Areal surface topography representation of as-built and post-processed samples produced by powder bed fusion using laser beam melting

Abstract

The increasing interest in Additive Manufacturing (AM) is due to its huge advantage in producing parts without any geometrical limitations. It is due to this reason, AM is extensively utilized in automotive, aerospace, medical and dental applications. Despite their popularity, AM is often associated with inferior surface quality which is one of the many reasons why it has failed to fully replace traditional methods. Hence, AM is always followed by a subsequent post-processing step to produce the end-product. To establish control over the surface quality it is first necessary to fully understand the surface behaviour concerning the factors affecting it. In this paper, the focus is mainly on having a better understanding of the surfaces by using scale-sensitive fractal analysis. In addition, the paper documents the influence of build inclination and post-processing in particular shot blasting on surface topography and utilizes a multi-scale approach to identify the most important scale and parameters for characterization. Results of this study reveal that shot blasting has a minimalistic effect on surface features at a large scale as it cannot remove the waviness completely. At smaller scales, blasting imparts additional features on the surface due to the impact of abrasive particles at high pressure. At the intermediate scales, the influence of shot blasting is highest as it successfully eliminates the surface features comprising of partially melted powder particles and stair-step effect.