A Combination of 3D Printing and Casting Technology Ensures Lighter and More Durable Agricultural Machinery Components
Lighter, stiffer and more resistant — this is the result of the redesign of an agricultural machinery component, in which 3D printing and casting were combined.
In its original design, the swing arm for the Catros 2TS disc harrow was a complex, 245 kg heavy component connected with a total of 16.5 m of welded seam. The high number of welds made production expensive and time-consuming. Reason enough for Amazone's engineers to look for an alternative manufacturing process.
Amazone develops and produces high quality agricultural machinery for economical agriculture. The company's most recent projects include the redesign of a swing arm. The aim was to make this component lighter, stiffer and more resistant. The undercarriage swing arm connects the harrow with the axle of a tractor that is used to transport the implement from the farm to the field.
At the beginning of their analysis, Amazon engineers found that changing the production method from welding to casting offered a high potential for weight reduction. At the same time, this adjustment made the production of the component less complex, cheaper and faster. Since the component can now be cast in one piece, production is also less prone to errors.
Casting Instead of Welding
First of all, Amazone optimized the topology of the new component design. The engineers used the Solidthinking Inspire software tool for this purpose. After defining the installation space, benchmarks such as loads, required rigidity and production conditions for the casting were added. In this step, they also defined the areas in which the structure had to remain unaltered, e. g. bearing points or cylinder connections.
The results provided the engineers with the basis for a detailed design, which they could use for an FE analysis with Optistruct. The results speak for themselves: the cast component significantly lighter than the welded structure and, thanks to softer transition in the structure, deviations in stiffness could be reduced as well. The tests showed that the fatigue strength of the cast component increased by a factor of 2.5 compared to the welded component, while the weight could be reduced by 8 %.
3D Printing and Casting
The promising results from the re-design and the application of new production methods motivated the engineers to look for further ways to improve the component. The engineers found one of these possibilities in additive manufacturing, which — combined with casting — could make the component even lighter. For this step in the process, Amazone turned to Altair and Voxeljet. In a joint project conducted in 2015, the companies successfully combined 3D printing and casting technologies. Voxeljet produced the required molds for the component using 3D printing technology.
As part of the new process, Amazone developed an optimized topology that takes into account the new production benchmarks that had to be applied for the 3D printing and casting processes. As a result, the weight of the new component could be reduced by a further 11 % without impairing the original fatigue strength and rigidity of the cast component.
The use of the Solidthinking Inspire tool ensured a smooth design process. Afterwards, Solidthinking Click2Cast (C2C) was used to simulate the casting process. Thanks to C2C, the engineers could use casting simulation to determine whether the new design could be cast according to plan. In the early design phase, the designers used C2C to optimize the component design and verify the producibility of the components in order to avoid errors and detect critical areas. Additionally, by using Inspire and C2C iterations between design and manufacturing could be significantly reduced. Even at the end of the design process, C2C is successfully used by simulating the complete mold filling process and solidification of the material. This simulation contributes to the control of the filling process and improves the quality of the components.
Saving Time Through 3D Printing
Usually, the production of molds for such a complex component is time-consuming. For this reason, Voxeljet produced the tools required for the casting process from quartz sand, using the powder-binder-jetting process. Casting of the swing arm is carried out at Pro Cast Guss.
The combination of 3D pressure technology and casting delivers excellent results: The prototype of the suspension swing arm weighs only 200 kg.
This article was first published by konstruktionspraxis.
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