Laser Powder-Bed Fusion of Metals: Density, Geometric Freedom, Residual Stress, Supports, Productivity and Qualification

Laser-based powder-bed fusion of metals, designated PBF-LB/M by ISO/ASTM and widely called LPBF, SLM or DMLS, selectively melts successive powder layers to create near-net-shape metal components. Its industrial value can include tool-less geometric complexity, internal features, part consolidation, rapid design iteration and high material utilisation relative to subtractive routes for selected geometries. Those benefits are conditional. The deposited layer is a heterogeneous granular state; laser–matter interaction can move among incomplete fusion, stable conduction-like melting and keyhole behaviour; plume, condensate, ejecta and gas flow redistribute energy and material; supports conduct heat and restrain distortion while adding removal and surface burdens; and rapid cyclic heating creates microstructure, residual stress and location dependence. The as-built object normally requires controlled cooldown, powder removal, plate separation, support removal, heat treatment, machining or finishing, cleaning and inspection. This qualitative engineering review maps that state-resolved chain and its principal failure modes. It explains why volumetric energy density, relative density, scan speed, nominal oxygen level or a single in-situ signal cannot serve as universal qualification metrics. It proposes powder, machine, build, post-process and acceptance records aligned with current ISO/ASTM controls and bounded primary evidence. The resulting selection gate accepts PBF-LB/M only when geometry, alloy state, support/recovery access, complete-cell productivity, safety, inspection coverage and change control are demonstrably compatible with the required delivered component.

3Dresyns Engineering Review ER-145, version 0.2. Provider-neutral technical review.