Green laser enables additive manufacturing of copper by selective laser melting
September 10, 2017
Source: ASM International
The Fraunhofer Institute for Laser Technology ILT, Germany, has developed a new approach that incorporates a green laser for selective laser melting of copper materials. The new process should offer users the first cost-effective AM method for components made of pure and highly conductive copper.
As part of a research project funded by AiF German Federation of Industrial Research Associations, the Fraunhofer ILT researchers are looking to develop the SLM process to make it more suitable for the additive manufacturing of components made of copper alloys and pure copper. Pure copper in particular is an attractive option for end users, as it is more electrically and thermally conductive than copper alloys.
"Depending on surface properties, pure copper reflects most of the laser radiation in conventionally used wavelengths of one micron," says Daniel Heussen, Research Fellow in the Rapid Manufacturing group. "As a result, only a small portion of the laser energy is deposited in the material and, thus, is available for the melting process. The reflected radiation can also damage the components of the system. In addition, the absorptivity of the material for the infrared light rises rapidly as the material transitions from a solid to liquid state, thus triggering an unstable and intermittent remelting process."
Green laser light with a wavelength of 515 nm makes the absorptivity of pure copper 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. A specially developed laser beam source, which operates with green rather than infrared light, will be designed at the Fraunhofer ILT by the end of 2017.
According to Dr. Heussen, "We are hoping for more homogeneous melt pool dynamics so that we can build components with high material density and achieve other positive effects, such as higher detail resolution."
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