ETH Zurich researchers develop novel DfAM framework for multi-flow nozzle designs

A duo of researchers from ETH Zurich have developed a computational Design for Additive Manufacturing (DfAM) framework capable of automating the design of complex multi-flow nozzles.

The framework acts as an alternative to the conventional CAD software used by engineers today, but allows non-specialist users to design complex geometries specifically for additive manufacturing tooling purposes, such as FDM nozzles. The method also enables on-the-fly design iterations and computational fluid dynamics (CFD) analysis on the generated nozzles.

The nozzle geometry generation process. Image via ETH Zurich.
The nozzle geometry generation process. Image via ETH Zurich.

Complex parts require complex tools

The ability to produce organic shapes is heralded as one of the key advantages of additive manufacturing. What is often overlooked, however, is the actual design phase where concepts materialize and begin to take shape. Despite decades of advancements, the conventional 3D CAD software of today is still based on low-level, primitive foundations, and requires an abundance of repetitive manual steps to produce anything resembling organic.

Topology optimization software has somewhat filled this niche in recent years but still requires a high level of human interpretation and a base model to optimize. It may also not be suitable for certain functional applications involving multiple integrated fluid flows, such as multi-material nozzles. A fully automated novel process is therefore required for such parts, and is, in essence, what the framework tries to accomplish.

The DfAM framework

The DfAM framework provides users with a toolbox of design elements, each corresponding to a certain building block that can be used to generate the final 3D nozzle design. These building blocks are organized in a hierarchical (almost modular) structure and presented in a visual manner, so it’s impossible to accidentally skip a step or component and end up with a non-functional nozzle design. As a result, the framework is very user friendly and can be picked up by non-technical professionals.

Overlaps between design elements are accounted for in the final geometry. Image via ETH Zurich.
Overlaps between design elements are accounted for in the final geometry. Image via ETH Zurich.

To test the framework out, the researchers designed and 3D printed a set of additive manufacturing nozzles capable of co-extruding multiple sources of clay. The design process involved selecting the inlet and outlet shapes, and stacking various design elements on top of each other. The arrangement of the design elements automatically translated to the corresponding multi-channel nozzle geometry.

In the background, the framework also checked the wall thickness and overhang values of the part to ensure the design was 3D printable, eliminating any design elements that would not be compatible with the other parameters. Eventually, the nozzles were printed successfully, confirming the efficacy of the framework. The next steps for the research entail  the development of design elements that are more dynamic in nature, ones that adapt themselves around restrictions rather than excluding themselves entirely.

Designing, 3D printing, and testing the multi-clay co-extrusion nozzles. Image via ETH Zurich.
Designing, 3D printing, and testing the multi-clay co-extrusion nozzles. Image via ETH Zurich.

Further details of the study can be found in the paper titled ‘Computational design synthesis of additive manufactured multi-flow nozzles’. It is co-authored by Manuel Biedermann and Mirko Meboldt.

Also seeking multi-flow 3D printing, researchers from Harvard University have previously developed a novel method of additive manufacturing they call multi-material multi-nozzle 3D printing, or MM3D. The process consists of a printhead containing multiple channels for the delivery of up to eight different materials through one single nozzle. The nozzle has the ability to switch between channels up to 50 times a second, with Y-shaped junctions preventing any unwanted backflow or mixing of materials.

Elsewhere, demonstrating the power of new design paradigms, a team of six international scientists recently developed a new computational framework for the multi-axis, non-planar 3D printing of polymer parts. The FFF-based technique works by aligning filaments along the direction in which they experience the greatest stress rather than in flat, horizontal layers. This increases the overall strength of the part, with some components showing up to 6.35x strength increases when compared to conventional planar FFF printing.

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Featured image shows the design, 3D printing, and testing of the multi-clay co-extrusion nozzles. Image via ETH Zurich.



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