21st September 2017
Under the umbrella of the joint project “LightHinge+”, EDAG Engineering GmbH, voestalpine Additive Manufacturing Center, and Simufact Engineering GmbH have joined forces to demonstrate the practical use and potential of additive manufacturing technologies in automotive production. LightHinge+ is an additively manufactured hood hinge that combines lightweight construction and increased safety in a single construction.
“Engine hood hinge systems are very complex because of the high demands on safety and functionality,” says Dr. Martin Hillebrecht, Head of Competence Center Lightweight Construction, Materials and Technologies at EDAG Engineering GmbH. “This means that lightweight construction is still on the line. That is why, together with voestalpine and Simufact, we have set ourselves the goal of rethinking the hinge by means of generative production.”
The EDAG engineers have re-designed the hinge system. In the second step, the topology optimization of the complex component structure followed to achieve the desired weight advantage. Using bionic principles, EDAG engineers were able to determine the minimum material requirements and achieve a 50% weight advantage over the reference. The subsequent optimization of the support structures was carried out in close cooperation with the voestalpine Additive Manufacturing Center.
“The topology optimization calculates the minimal material requirements of the hinge,” explains Dr. Eric Klemp, Managing Director of the voestalpine Additive Manufacturing Center in Duesseldorf, Germany. “The resulting components geometries require a high proportion of support structures, which we could then minimize to a minimum in the project,” says Dr. Klemp.
An important step in the design and production of additive components is the simulation of the actual build process in the 3D printer. Here, Simufact came into its own with its software solution “Simufact Additive”, specially developed for additive production. “In the additive manufacturing process, the concentrated heat input with high heating and cooling rates causes distortion and residual stresses in the component,” says Dr. Patrick Mehmert, Product Manager Additive Manufacturing at Simufact. “A non-distortion-compensated hinge can thus deviate from one to two millimeters to the reference geometry respectively.”
With Simufact Additive, the actual printing process and the subsequent process steps can be simulated and thus distortions and residual stresses can be predicted. “On the basis of simulated distortion, we have negatively deformed the component geometry so as to minimize the shape deviations of the printed hinges to the target geometry,” Mehmert describes the procedure in the project.
The fact that this method also achieves the desired results was shown by the adjustment of the distortion-compensated components following the printing of the parts: A three-dimensional optical measurement performed by AICON 3D Systems proved the dimensional accuracy of the components.
The simulation of the build process has contributed significantly to the improved design, protection and distortion optimization of the additively manufactured LightHinge+ hinge. Expensive and time-intensive production tests could be prevented.
In the end, the voestalpine Additive Manufacturing Center achieved an economical, resource-saving production with low rework. The hinge is thus as good as ready for use after the laser melting process.
“The LightHinge+ hood hinge fully exploits the potential of additive manufacturing by means of efficient software-assisted engineering,” Dr. Martin Hillebrecht summarizes. “An ultimate weight reduction and integration of a pedestrian protection function, in distortion and self-tension optimized tool-less production with little rework for small series is achieved.”