An overview on post-processing of metal additive manufactured components

Abstract

Additive manufacturing (AM) is a rapidly evolving manufacturing technology capable of producing complex near net shape products based on a 3D digital design data. The scope of mass customization, design freedom and batch production establishes the supremacy of AM over traditional manufacturing methods. Metal AM technology is capturing significant attention in aerospace, biomedical and automotive industries due to the never-ending demand for customized and complex parts. However, the direct implementation of metal AM components is not recommended owing to the poor surface integrity, dimensional inaccuracy and mechanical anisotropy. The metal AM parts are characterized by the presence of many defects/irregularities such as balling defect, stair-stepping effect, incomplete fusion defects, cracks and voids/porosities. The surface defects together with solidification shrinkage phenomenon lead to loss in dimensional and form deviations of the metal AM components. Further, the microstructural variations in the fabricated part along various directions relative to the build orientation causes anisotropy in mechanical properties. Post-processing operations form the concrete solution to overcome the aforementioned challenges in metal AM parts. The well-established post-processing variants for metal AM components can be categorized into surface finishing methods, mechanical impact treatments and thermal processing methods. The surface post-treatment variants utilize various sources including laser, abrasives, chemicals, electro-thermal energy and mechanical forces, whereas heat treatment and hot isostatic pressing (HIP) constitute the thermal processing methods. A comprehensive outlook on the working mechanism and research trends related to the metal AM post-processing methods forms the crux of the chapter. Moreover, the directions of future research with regard to digital twin driven post-processing using machine learning modules and artificial intelligence aided automation have been portrayed from the standpoint of Industry 4.0.