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Shortening the design cycle and customizing with TPU

The third and final installment on automotive innovation and the Green Deal. Read how new modeling technology and the use of TPU could be part of the answer.

Fabian Grupp
June 3, 2020

We are now into the final blog of my European Green Deal blog series; the first two were: The European Green Deal: Pressure to Innovate and How Lightweighting and Copper Might Drive Automotive Innovation. I began with going over what the Green Deal is and what it might mean to the automotive industry – especially in Germany. Then I followed up with some applications where I think AM can make an immediate, direct impact. Now, I’d like to go over how I think new modeling technology can help shorten development cycles bringing the automotive industry closer to Green Deal standards. 

New modeling technology as an innovation catalyst

nTop Platform’s modeling technology is based on field-driven design and our geometry kernel can both create and handle unlimited complexity. That means engineers are able to use a broad array of data to automatically and intrinsically drive their designs. It’s possible to use both simulation data and actual, physical data (from a thermal camera, for example). 

A nice use case for how this field-driven design works within nTop Platform is from our friends at Cobra Aero. They designed and optimized the cylinder of a UAV engine to account for thermal fields, pressure fields, and flow velocity factor fields. They additively manufactured this new design – a lattice infill structure – and (spoiler alert) found it outperformed their previous finned design. While this is not for use in a car and it’s made from aluminum, the principles can be easily transferred to the automotive industry. 

What’s more, engineers don’t just create a part with our software, they create a custom development environment they fully control. It recalculates, mostly in milliseconds, whenever any building block of the workflow is changed no matter if it’s an upstream or downstream change in the design. Ultimately, design engineers don’t just create one part, instead, they build a meta tool capable of producing countless part variations according to spec. They effectively create a set of design rules in relation to each other instead of designing a singular, static object – a powerful design paradigm. 

For example, say you are working for a company that needs to develop a larger heat exchanger for a particular electric vehicle model. Rather than starting from scratch for each car model (or part), you can reuse a workflow from a prior project: feed it with the updated thermal simulation data and automatically create a new, higher-performing heat exchanger for that car model. Imagine the time saved!

TPU – the time is right


Example of TPU, a soft and elastic material, great for protective gear, shoe soles, or cushioning.

A material that, in my view, has the potential to drive innovative applications is thermoplastic polyurethane (TPU). In the past, a lot of specialized AM service providers have been working with TPU powders – some of them quite successfully. However, we’re seeing a broader availability in the industry now for a few reasons:

  • Important machine manufacturers, namely EOS and HP, have developed stable process parameters and have marketed the material to their customers
  • Three major material suppliers offer TPU powders: BASF, Lubrizol, and Huntsman
  • The flexible material is well suited for functional lattice design  

TPU is a soft and elastic material. EOS lists a shore hardness of 86A. This makes it a great candidate for protective gear, shoe soles, or cushioning elements. In addition, higher wall thickness increases the stiffness which adds another dimension for tailoring part properties.

Lattices in customization

The iconic German sports car manufacturer, Porsche, announced 3D-printed seat cushioning in three degrees of firmness each with different lattice density defining how the structure collapses and therefore how soft it is. As of now, the functional advantages are less weight, higher comfort, and passive cooling properties. 

To take it a step further, with the above-mentioned workflow capability within nTop Platform this could quickly evolve into actual customization to take the individual driver into consideration. We can automatically adjust all filets on a complex lattice design depending on a driver’s build or how long they tend to commute, for example.

 

EOS Digital Foam video illustrates custom and gradient lattice design for comfort, safety, and lightweighting. Video courtesy of EOS. 

Commercial aspects of TPU

3D-printing has gone through the textbook progression of the Gartner Hype Cycle and is well on its way out of the “Slope of Enlightenment” and moving into production. New applications are currently being vetted with a strong focus on commercial viability with the caveat in mind that just because you can print something does not mean that you should.

And admittedly, a volume-based process like SLS might not look like the fit for lofty and airy designs such as lattice structures. With the common PA12, most SLS users aim for the highest packing density in their powder bed machines, not only to maximize machine time but also because the powder takes thermal damage and can’t be used for infinite runs. 

TPU is different – with a refresh rate as low as 20% the powder can be easily recycled. If over three-quarters of the powder mix can consist of used material, the economy of the process changes significantly: maximizing machine use is the main concern that matters. 

These are just examples and, of course, the actual use cases must prove to be more than a flashy feasibility study. However, there is a solid indication that TPU based lattice design, additively manufactured heat exchangers in copper and nTop Platform’s modeling technology are promising examples for how AM and new technology enable innovation.

This is only the beginning…

Now that we’ve come to the end of my series, I hope you’ve seen it’s really only the beginning of what can become of automotive innovation.  The pressure to innovate should not stymie the industry but rather be seen as a catalyst for creating better, higher performing, and less environmentally destructive designs. 

As mentioned above, in nTop Platform, you can build higher-performing heat exchangers efficiently by reusing workflows. To learn more about heat exchanger design in our software, check out this video.

Written by
European Business Development Manager
Fabian Grupp is the European Business Development Manager at nTopology bringing over 8 years of technical and managerial experience in additive manufacturing. He began his career as the Product Manager for the first German consumer FDM printer which was developed and manufactured in Bavaria. He then transitioned into the AM software side as an OEM Manager at Netfabb (acquired by Autodesk in 2015). He continued his career at the intersection of machine and software where he ran Product Management Additive at Autodesk, responsible for the Netfabb product line, Within Medical, Meshmixer and the additive experience in Fusion360. Fabian joined the nTop team in 2019.

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