Amazone develops and produces innovative agricultural technology with a high standard of quality, enabling and supporting modern and economical arable farming methods. With these standards in mind, Amazone leverages advanced development tools, processes, and manufacturing methods to contribute to its customers’ success. Agricultural machinery is used under very harsh and extremely varying conditions. In addition to service quality and the availability of spare parts, product longevity is a key purchase criterion for farmers. When developing a new product, manufacturers not only have to be competitive regarding price, they also have to consider the durability of the product, since this aspect impacts the manufacturer’s reputation in the marketplace.
New manufacturing methods for higher longevity and economic viability
Agricultural machinery and related equipment have seen an enormous increase in efficiency during the last decade. By increasing the ground coverage with, for example, higher throughput rates, expanded cutting units, and higher tank capacities, overall productivity has been significantly enhanced. However, the equipment must still be robust enough for harsh operating conditions, and design improvements must not lead to higher prices for the final product.
This is where new development and manufacturing processes come into play. In addition to the material resources saved in the production process by using a load-specific structural design, product durability and weight can be improved at no additional cost to the end user with a targeted, manufacturing-oriented, optimised development process.
CAE model of the original welded construction
Amazone recently conducted a project in which a suspension component for a soil tillage unit was subjected to optimisation to evaluate the part’s material usage and durability. The unit was the trailed compact disc harrow, Catros-2TS, which CAE model of the original welded construction is pulled by a tractor and can be used in different configurations. The compact disc harrow is used for intensive mixing and shallow cultivation (working depth up to 15 cm).
Light-weighting this component offers another benefit to farmers. With a lighter suspension component, he might have more options to choose from for add-on equipment. For example, if necessary, he could pick a heavier roller for a more intensive soil reconsolidation, and the overall allowed axle load would not be exceeded with the lighter suspension component.
In addition to a design space, non-design space areas were defined in solidThinking Inspire as well, where the structure was not be modified, for example at support points or cylinder connections.
From a welded construction to a cast component
Originally the Catros-2TS was a rather complex welded part with a weight of 245 kilograms, including a total of 16.5 metres of weld seams needed to join the single parts. This amount of welding made production very time and cost intensive. Approximately 350 units of this component are manufactured each year. To meet the goals of optimising the component’s manufacturing process and increasing its longevity, Amazone engineers not only gave the component’s design a closer look, but also evaluated the potential benefits a new manufacturing method, in combination with topology optimisation, could offer.
In addition to a design space, non design space areas were defined in solidThinking Inspire as well, where the structure was not be modified, for example at support points or cylinder connections
Based on previously defined loads and boundaries solidThinking Inspire calculates the optimal structure
Simulation and casting technology for an optimised suspension component
The first step was to evaluate the weight savings and performance increase of the component if produced using a casting process. To do so, the engineers conducted an upfront topology optimisation. In addition, Amazone employed a simulation driven design process to eliminate unnecessary design iterations and reach a final design faster. These tasks were handled with Altair Engineering’s structural solver and optimisation tool OptiStruct and solidThinking Inspire.
The engineers expected several advantages from the casting method. Since the component can be cast in one piece and needs no welds, production is much simpler and the process less error prone. The engineers expected to see a significant cost reduction and optimisation potential for the manufacturing process, resulting from the optimised structural design created with the optimisation tools.
To optimise the structure, the engineers used solidThinking Inspire. First they defined the possible design space and the boundary conditions, such as loads, required stiffness, and manufacturing restrictions. Non design space areas were defined as well, where the structure was not be modified, for example at support points or cylinder connections. Calculation time was further reduced by defining and applying a symmetry plane, which helped to receive results faster. With these inputs, the software calculated how much material was needed and at which position it had to be placed in order to meet requirements such as structural strength.
Refining of the optimised geometry in solidThinking Inspire
When compared to the welded construction (left), the casted version realised a lower weight and smoother transitions of the structure, resulting in fewer stiffness variations
From the optimisation result, the engineers created a detailed design that was then evaluated in a FE analysis with OptiStruct. When compared to the welded construction, the cast version realised a lower weight and smoother transitions of the structure, resulting in fewer stiffness variations. The overall loading in the cast material of the new design was significantly lower compared to the loadings in the weld seams of the original assembly. Thanks to the load specific structure of the casting part, subsequent physical tests showed durability increased by a factor of 2.5 while the weight was reduced by 8 per cent.
Benefits and outlook
The new version of the suspension component is already in operation and has reduced Amazone’s manufacturing costs by one-third compared to the former welded construction. Thanks to the reusability of the casting mould, tooling costs were quickly amortised. Customers have benefitted from a higher flexibility in add-on modules and improved product longevity.
Currently, Amazone engineers are looking into further optimisation of the cast part structure and the manufacturing process by leveraging a combination of topology optimisation and 3D printing. Altair has presented a best practice example of this approach with its partner voxljet. In this process, a lost-wax casting mould is created with 3D printing and the structure of the component is optimised and inspired by natural shapes, which fit perfectly to what can be realised in 3D printing. Simulation and optimisation runs have already been concluded and resulted in a further potential weight saving of about 11 per cent, while keeping durability and stiffness at the same level as with the cast part. Final cost calculations are still pending and will be one of the key factors of Amazone’s decision whether or not to use this process for series production.