Germany-based Fraunhofer Institute of Laser Technology have developed a novel new laser powder bed fusion technique. The new process leads to parts with far lower rates of distortion and stress as they fuse metal. The technique can thus create very high quality parts with a new heat balance in the build chamber. The company will debut their work with low-distortion LPBF printing at formnext 2018.
Fraunhofer ILT is currently working with infrared laser specialist Philips Photonics on a Digital Photonic Production DPP research initiative under the title DPP Nano. The project is also government funded. The printing system uses a heating system that raises the bed temperature from below. This one heat source alone, however, would cause internal thermal stresses throughout the print, which can lead to defects.
So, the company also uses a DPP Nano project system with an additional heat source at the top. The six vertical-cavity surface-emitting laser bars (VCSEL), as shown above, makes this arrangement of heat sources possible. Independently operable, each VCSEL bar emits 400 W of power, providing 808 nm infrared radiation. Through the use of these bars, components heat up to several hundred degrees Celsius, viewable with infrared camera monitoring.
Improved Powder Bed Technologies
As the picture above shows, there is far less less distortion of the metal on the right in comparison with the left. The former received heat from below only, while the latter was given the full heat array treatment. This is thanks to the new technology system. While it doesn’t reinvent the wheel, it certainly improves its consistency in action.
That proof of concept test had Fraunhofer ILT scientists 3D printing a component made from Inconel 718. The component heated up to a temperature of 500 °C. It’s one of many tests that attempt to regulate the metal 3D printing techniques that craft complex items, but show very low levels of control. Powder bed technologies are going through an evaluation phase right now. This is a crucial step forward for bringing the process up to scratch.
Featured image courtesy of Phillips Photonics & Fraunhofer ILT.