Engine Bracket

Especially in large-scale transitions to Additive Manufacturing, it’s crucial for manufacturing companies to know the final 3D printed component will meet their engineering requirements and specifications precisely, reliably, consistently, and safely. To guarantee Liebherr Components this ease of mind, Forward AM’s Virtual Engineers ran digital simulations precisely predicting the behavior of the new material, and then demonstrated the performance of the final part mounted in the engine. The key tool for all extensive simulations and Virtual Engineering at Forward AM is Ultrasim^® – a BASF-developed software collection that allows simulation specialists to incorporate the complex nature and behavior of thermoplastic materials with very high accuracy.

Focusing on the material for the bracket, Forward AM’s advanced metal filament Ultrafuse^® 316L was the perfect match: This metal-polymer composite filament enables the production of key components in surgical-grade 316L stainless steel – ideally suited for jigs and fixtures, spare parts and functional prototypes such as the part Liebherr Components now produce with Additive Manufacturing.

After initial clarification and definition of the requirements of the final component, Forward AM’s Virtual Engineers began mapping out the entire development process from concept to final part. Since the initial part was designed and built around traditional manufacturing, digital topology optimization was the first step in fully harnessing the benefits of Additive Manufacturing to identify the best-possible component structure. This process is only possible through Virtual Engineering and the radically expanded design freedom that 3D printing provides.

The optimal structure for the component is identified virtually, based on the mechanical forces applied in real-life operation. Digital simulation reveals which aspects of the part need to be retained, such as cutouts for screws, and where material can be eliminated as there are no significant mechanical or thermal forces applying. The topology optimization results in a wholly new component structure and makes it much lighter, as material is only used where it is needed. In the next step, Forward AM’s Virtual Engineers adapt the optimized topology to metal 3D printing, leveraging a design option that is only achievable with 3D printing: Integrating a lattice structure as infill for the part, making it much lighter without compromising on functionality or stability in any way.

By only using material where needed and integrating lattice structures as infill, the redesign of the bracket reduced its total weight from 343 to 167 grams – a huge reduction of over 50 percent. The lower weight logically also results in a lower price per part, as less material is used and thus less 3D print time is needed for manufacturing.
Following the ‘brown’ part simulation – a common step in metal 3D printing to predict the feasibility of the printing process – then virtual debinding and sintering, a structural simulation is conducted. By virtually installing the new Additive Manufactured engine bracket, it can be compared with the original bracket in terms of mechanical and temperature stress resistance, making sure the lattice structure performs successfully under harsh real-world conditions.

Virtual assembly ensures the Additively Manufactured part’s dimensions fit the final application. Additionally, a frequency analysis is conducted – evaluating whether the four engine brackets can withstand the very high operating loads of the aggregate structure, or whether they will stray into eigenfrequency. The result showed the eigenmodes exhibited behavior very similar to the original component. Taking it one step further, the Virtual Engineers at Forward AM added a key safety advantage, making sure the printed part not only withstands the specified operating loads but can safely withstand three times these forces.

After successful printing, the part undergoes an extensive 3D scanning process to compare its dimensions with the previously generated simulation. After analyzing the alignment, comparing surfaces and checking precise dimensions, the high accuracy and high-performance quality of the final part for Liebherr Components was proven.

This enabled Liebherr Components to give the green light for manufacturing the brackets and mounting them in the target application. Liebherr Components undertook exhaustive testing on the stand, precisely analyzing whether the performance of the simulation-generated component met their exacting quality and functional standards. To promote a more effective real-world assembly process, Liebherr Components requested the integration of two extra bolt threads in the new bracket. By ‘thinking additive’ and aligning production with AM, this was possible without having to add even one further manufacturing step!

Making the transition to AM yields numerous benefits for LiebherrComponents: The bracket is manufactured at greatly reduced cost, time and weight, and ensures identical load-bearing capacity. Having achieved a deeper understanding of AM technology and the advantages it brings, Liebherr Components have now launched in-house printing using an Ultimaker 3D printer and is planning the global rollout of AM in their production facilities around the world.