​The finishing step of additively manufactured metal components may be categorised into three mechanisms: 1) mechanical, 2) thermal and 3) (electro-)chemical processes. In this article, we review the effectiveness and impact of mechanical subtractive techniques on finished AM components.

Balling is a defect that can occur when the molten pool created during selective laser melting (SLM=L-PBF) becomes discontinuous and breaks into separated islands. In this post, we report and discuss how the powder particle arrangement impact the bead geometry and formation of balling defects during SLM.

Process parameters development is a rigorous multi-step process paramount to manufacturing repeatability and reliability of production. Amongst ensuring high density, suitable surface roughness and reliable mechanical properties, dimension accuracy and precision must also be guaranteed as part of the ideal (ie no mechanical post processing involved) AM process. Here, we review the critical factors that can be used to ensure dimension accuracy. 

Fully dense components built using selective laser melting exhibit mechanical properties equivalent or even better than those of parts produced by conventional manufacturing [1] [2]. But building components using SLM sometimes requires external support structures. These support structures are necessary for a few reasons: they strengthen and fix the part to the building platform, they conduct excess heat away and they prevent warping or complete build failure.

Commercial viability of laser-based 3D printing and its general acceptance as a valid production technique resides in how it can limit the need for post--surface or -heat treatments. Surface roughness, with its capability to affect air flows and aerodynamics is a critical factor in aerospace or medical applications. The efficient function of high value components, such as combustion chambers in turbine engines, relies on high quality and controllable surface finish.