Shaped body especially prototype or replacement part production - by CAD data-controlled laser melting of successively applied individual metal powder layers.

Abstract
A process for producing a shaped body, especially a product or component prototype, a tool prototype or a replacement part, according to three-dimensional CAD data of a model, involves applying metal powder layers, each of which is fixed to the underlying layer, prior to applying the next layer, by heating in a predetermined region using a focussed laser beam which is guided over the powder layer in accordance with CAD cross-sectional data corresponding to a selected cross-sectional region of the model. The novelty is that (a) a binder-free and flux-free metal powder is applied and is heated by a laser beam of sufficient energy to produce complete melting over the entire layer thickness at the beam incidence spot; (b) the beam is passed along several tracks over the predetermined region of the layer, each track partially overlapping a previous track; and (c) a protective gas atmosphere is maintained over the interaction zone of the beam with the powder. ADVANTAGE - The process permits production of a prototype (e.g. an exhaust gas manifold prototype) which can be tested under conditions (e.g. high temperatures and high mechanical stress) corresponding to those to which the subsequently mass produced product will be exposed, the prototype having a homogeneous solidified structure and a strength and density at least approximating those of the end product and not requiring expensive post-treatment steps. The starting powder can be selected from a wide variety of metallic materials (e.g. special steels, aluminium or titanium), does not require pretreatment and only requires a sufficiently fine particle size to permit build-up of finely graduated individual layers.