Green Light SLM Method for Copper
Fraunhofer ILT researchers are exploring using selective laser melting (SLM) to additively manufacture (AM) components made of copper alloys and pure copper. While SLM is used to process steels, titanium, and aluminum alloys, as well as nickel and cobalt alloys, copper is a struggle. SLM is currently only suited for copper alloys due to pure copper reflecting most of the laser radiation, Fraunhofer ILT researchers hope to develop a laser beam source that operates with green rather than infrared light by the end of 2017.
With no "green" laser source on the market meeting the boundary conditions of the SLM process, the department for laser beam source development at Fraunhofer ILT is building its own in a project they call "SLM in green." Their aim is to create a high-quality laser for single-mode operation that functions with a maximum output of 400 watts in continuous service (cw) with green wavelength (515 nm). A "SLM in green" laboratory setup is expected to be ready by the end of 2017. Thereafter, the Fraunhofer ILT will further develop its processes as part of a research project funded by AiF German Federation of Industrial Research Associations.
By using green laser light with a wavelength of 515 nm, the absorptivity of pure copper is much higher. This means that less laser power output is needed for a stable process. Furthermore, the laser beam can be focused more precisely, allowing it to manufacture far more delicate components using the new SLM process.
The primary future goal is to create a reliable process with which industrial users can 3D print complex geometries of pure copper with hollow structures and undercuts. The process can be used for highly efficient heat exchangers and heat sinks or for the production of delicate, complex electrical components in small batches.