As the 3D printing industry looks toward leveraging the technology for industrial production, experts are working hard to figure out the best ways to make each type of 3D printing technology work best from a production standpoint. For FDM 3D printing, that involves developing ways to print with tougher materials. For all technologies, it means increasing productivity, and in many cases, build volume.
Increasing productivity and build volume is what researchers at Fraunhofer Institute for Laser Technology ILT are working on for Selective Laser Melting (SLM) technology right now. The institute has done quite a bit of advanced research into SLM technology, and its latest development involved the construction of a large SLM additive manufacturing system with a build volume of 1000 x 800 x 500 mm. That’s an unprecedented size for an SLM system, and Fraunhofer ILT’s goal is to show that SLM machines can also be scaled to larger sizes. The current machine is a test system; it has demonstrated the ability to print large items quickly and reliably, but work is still ongoing.
“The focus of development work is on new strategies for exposure and shielding gas flow,” said Christian Tenbrock, a scientist in the Rapid Manufacturing group.
The inert gas strategies that are currently used aren’t effective for such a large build volume, so Fraunhofer’s researchers are working with small, moveable processing heads with a local shielding system. This ensures a constant stream of inert gas at every processing point, no matter the build size.
The scientists are currently testing systems with fiber lasers as well as exposure concepts with cost-effective diode lasers. While they are conducting research into established scanner systems with mirrors, they’re also looking into a moving processing head with highly dynamic laser axes and several individually controllable diode lasers. By increasing the number of beam sources, they would be able to increase the system’s build-up rate in a cost-effective manner. In addition, they could increase the build volume just by extending the travel length of the axis system, without changing the optical system.
“Because both optical systems have their characteristic pros and cons, we will continue to pursue both approaches,” said Tenbrock.
The scientists intend for their research to be used by 3D printer manufacturers as a blueprint from which to build larger SLM machines. SLM is actually an easier technology to adapt to large-scale 3D printing than others, as there is no need to adjust the shielding gas system and the optical system.
“We hope that the system concept will lead to a breakthrough in the successful use of this technology in series manufacturing,” said Tenbrock. “We create process conditions that are constant and easy to control, thereby improving process robustness.”
Developing a new additive manufacturing system, particularly such a large one, doesn’t stop at creating the machine, however. The Fraunhofer researchers also had to develop the parameters for efficient process management.
“The added value is created through intelligent strategies for exposure and path planning as well as suitable process parameters,” said Tenbrock.
The long-term goal is not only to develop new applications for SLM technology but to address common SLM challenges, such as internal stresses and distortion. Ultimately, the researchers plan to develop an entire system that will make it possible to manufacture large-scale parts for industries such as aerospace, automotive, and tool and mold-making industries.
Fraunhofer ILT will be at formnext, which is taking place in Frankfurt, Germany from November 14th to the 17th. The researchers will be demonstrating the new system’s large-scale capabilities through process videos. They will be available at the joint Fraunhofer booth, which is in Hall 3.0, Booth F50. 3DPrint.com will be on the scene all week in Frankfurt to keep up with the latest in 3D printing.
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