In addition to their use in prototyping and toolmaking, additive manufacturing processes are now increasingly being used in series production. Powder bed-based laser beam melting is particularly suitable for the production of metallic components. Here, the component is built up layer by layer by local melting the metal powder by a laser beam and subsequent solidification. The figure provides an overview of the individual process steps. First, the base plate is lowered by the desired layer height, after which the coater applies the powder. Then the powder is melted locally by a laser beam, whereby the energy input here must be selected so that bonding to underlying layers can occur. The advantages of this technology include the possibility of creating components directly from the CAD model, the almost unlimited freedom of shaping, and the high resource efficiency since powder that has not melted can be reused for subsequent manufacturing processes. However, the process-related temperature gradients result in deformations and residual stresses, which can have a negative effect on process stability and component quality.
Additive manufacturing by laser beam melting involves several special features, some of which have to be taken into account as early as the component design or production preparation stage. Examples are the staircase effect and the process-related necessity to build support structures together with the component.
Due to the layered construction, so-called steps result in gradients or curvatures of the component in the build-up directions. With low gradients and high layer thickness, this effect can become clearly apparent and negatively influence the component’s dimensional accuracy and surface quality.
During laser beam melting, components cannot be built up into the powder without further ado. If, due to design features, it is impossible to avoid this by a suitable orientation of the component in the build space, so-called support structures (supports) can also be built up. These are auxiliary structures that are built together with the component. Depending on the contour to be supported, there are several possible support structures:
- Block support
- Line support
- Web support
- Point support