Design Automation for Additive Manufacturing

Automating the design of additive manufactured parts

Despite the potential of additive manufacturing (AM), a key challenge is to design complex parts for AM. In practice, a common approach is to manually create the 3D geometry of parts using computer-aided design (CAD) tools. However, a manual design process can be challenging for several reasons. Firstly, it requires a lot of expert knowledge and skills with CAD tools. Furthermore, it often leads to a manual and time-consuming process of creating hundreds of design features with CAD tools. In addition, designers need to consider the product-related restrictions of the specific AM production technology, which can be difficult to implement for very complex-shaped parts. The manual design effort increases dramatically, especially if designers need to apply frequent design changes to include feedback from simulations and iterative tests or want to customize the geometry of parts to application- or customer-specific requirements.

Enlarged view: Design automation for additive manufacturing
Manual design of complex parts for additive manufacturing as a key challenge to leverage the design freedom of AM.

Given the challenges of a manual design approach, our research aims to develop novel design algorithms that automate the design of complex parts for AM. The basic idea is to provide design tools that automate frequently recurring and time-consuming tasks when designing AM parts. The goal is to assist novice but also experienced AM designers by capturing the required application- and production-specific knowledge and implementing automated design algorithms for AM. These algorithms are based on a rule- and knowledge-based engineering (KBE) approach. Our research work aims to demonstrate the potential of design automation for AM in different application domains such as fluid flow components.

Enlarged view: Additive manufactured nozzles tested using co-extrusion of clay
Automated design of multi-flow nozzles showing user inputs and automated generation of nozzles, as well as fabrication and testing of nozzles using co-extrusion of clay materials.

In one prior study, we show the automated design of multi-flow nozzles. For this purpose, the work presents a design toolbox for multi-flow nozzles. The toolbox includes various design elements that are frequently required for the design of nozzles, such as different cross-section shapes, flow channels, channel branches, guiding vanes, and reinforcement ribs. Users apply these design elements to specify the layout of a nozzle using a high-level definition of the required design elements (e.g., position and shape of channel cross-sections). Based on these intuitive user inputs, design algorithms translate the nozzle layout into a detailed 3D nozzle geometry. In the example, the design toolbox is demonstrated by showing the automated design of different nozzles that are tested using co-extrusion of clay materials.

Publication on automated design of multi-flow nozzles: external pagehttps://bit.ly/3aOSZhl
 

We aim to transfer our research results for different industrial applications. In a recent study, we demonstrate the development of additive manufactured dies for the co-extrusion of multi-layer profiles. The study was conducted together with the Institute of Materials Engineering and Plastics Processing (IWK) of the Eastern Switzerland University of Applied Sciences (OST). The study shows how an automated and simulation-based design process can be combined with additive manufacturing to develop nozzles for the co-extrusion of multiple polymer materials. The result is a very compact and flow-optimized co-extrusion die that was fabricated out of stainless steel using laser powder-bed fusion and successfully tested and validated at the very first attempt.

Publication on additive manufactured co-extrusion dies: Downloadhttps://bit.ly/3dBYFgm

Enlarged view: Additive manufacturing for co-extrusion of polymer profiles
Development of additive manufactured nozzles for the extrusion of multi-layer polymer profiles. Collaboration with the Institute of Materials Engineering and Plastics Processing (IWK) of the Eastern Switzerland University of Applied Sciences (OST).

In another recent collaboration with Planted Foods AG, we developed additive manufactured dies for the extrusion of meat substitutes such as plant-based chicken. In recent years, plant-based meat products have become more and more popular due to economic, environmental, ethical and health reasons. Traditional state-of-the-art extrusion dies are oftentimes not optimized for the extrusion-cooking of textured meat substitutes given the limitations and restrictions of conventional manufacturing methods. In contrast, the use of metal additive manufacturing enables the fast and iterative design, fabrication, and testing of novel die designs with new functionalities. Learn more about the development process by watching the video below.

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Development of additive manufactured nozzles for the extrusion of plant-based meat. Collaboration with Planted Foods AG.

Besides nozzles, our research work focuses on the automated design of flow manifolds. In recent studies, we present design algorithms to automate the design of hydraulic manifolds for AM. Again, the basic idea is that novice or expert users only specify top-level inputs. These inputs include functional requirements (e.g., inlets and outlets of flow channels, dimensions of channels) and restrictions of the chosen AM production technology (e.g., build direction, minimum build angle). Based on these inputs, design algorithms are used to automate the collision-free routing of multiple flow channels for separate fluid flows while considering the potential adaption of channel cross-sections to fulfill the AM overhang restriction. Solving this routing problem with a manual CAD approach is often a very challenging and tedious design task, especially for novice CAD users. The presented approach enables CAD users to automatically create the paths of flow channels and generate complex part designs that integrate multiple interlaced channels with several crossings in a tightly packed part.

Publication on automated design of hydraulic manifolds: external pagehttps://bit.ly/3xuraD8
Publication on automated routing of flow channels: external pagehttps://bit.ly/3SG3DKV

Enlarged view: Digital design and additive manufacturing of hydraulic manifolds with automated consideration of manufacturing constraints
Automated design of additive manufactured hydraulic manifolds, including routing of flow channels and generation of integrated and sacrificial support structures.

The developed design algorithms automatically transfer the user inputs into a detailed 3D part geometry that is ready for production with AM and does not need manual editing steps of the geometry. The generated 3D part geometries can be directly used for further steps in the development process, for example, to fabricate and test prototypes or conduct CFD and FEA simulations. Based on the automated design approach it is possible to automatically generate the design of customized parts that are for customer and application-specific requirements. In the presented study, the design algorithms are used to automatically create a detailed 3D part geometry of the hydraulic manifold for twelve individual specifications of potential customers. For each custom design variant, the approach automatically solves the routing of multiple crossing flow channels and considers the overhang restriction for laser powder-bed fusion of stainless steel. The manufacturability of the generated designs is shown by fabricating two design variants.

Enlarged view: Digital design and additive manufacturing of hydraulic manifolds with automated consideration of manufacturing constraints
Automated generation of hydraulic manifolds for different customer and application-specific requirements and fabrication of specific design variants out of stainless using laser powder-bed fusion.

Based on the presented studies, a key conclusion is that a rule- and knowledge-based approach can be applied successfully to automate the design of complex flow components for AM, such as multi-flow nozzles and hydraulic manifolds. Potential future research directions include transferring the results to different applications, further simplifying the automated design process, and integrating machine learning techniques.

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