We often talk about the general business advantages of Additive Manufacturing (AM) – the ability to move to secured digital supply chains, lowering overall supply chain costs, and enabling on demand manufacturing. There are, of course, also the development and design advantages everyone knows: complex geometries, moving parts, full assemblies as a single part, etc. All these are great abstract advantages, but seeing and discussing some actual parts is a great way to make additive manufacturing tangible and get inspired to apply advantages for other parts. Additive Manufacturing Media‘s Stephanie Hendrixson and Peter Zelinski have an ongoing podcast series called “the Cool Parts Show” that does just that. I’ve been a long standing fan of this show, which is both informative and well done, and it has inspired me to highlight 3 parts I think are cool, 1 of which is from that show while the other 2 are cool in more than one way. Here we go.
1. Vroom Vroom Vroom
The first part I’m highlighting is (unsurprisingly) a car part. In some companies, people shy away from critical parts and only move more peripheral parts to AM. Well, it doesn’t get more critical or subject to stress than a piston in a high performance engine. The part above is just that: a piston for the Porsche 911 GT2 RS engine. This part was additively manufactured in aluminum alloy on a Trumpf 3D printer (top pic shows a piston in the making). So, aside from high performance car engines being cool, what’s cool about this part? Thanks to AM, Porsche was able to lightweight the piston by 10%. Certainly not the 60–85% weight savings we sometimes see thanks to 3D printing but since this is such an important, highly used part, a 10% weight change makes a big difference. It enables the engine to rev up 300rpm more and increases the power by 30bhp (brake horsepower – the horse power taking into account power loss due to friction). In addition to the light-weighting there are some features Porsche was able to add to the piston thanks to AM. These include additional cooling ducts that cool the piston by 20 degrees Celsius in the crucial area behind the piston rings that seal the piston to the cylinder. All in all, this work horse (power) of a part improves the overall engine performance while using less material – definitely cool in my book!
2. No Assembly Required
Cobra Aero has been working on additively manufactured parts for a while now. Specifically, they were able to redesign their drone engine block from the finned look at the top left of the picture above to the latticed block in the picture below. That’s not the part I’ve chosen, though. During the pandemic, the Cobra engineers focused on the exhaust that connects to this engine – that’s the part that caught my eye (and the Cool Parts Show‘s attention as well). The original exhaust (in the picture above in the lower left quadrant) was made up of 13 parts that are bolted together and was very difficult to install on the drone because of limited access to the connector bolts. It weighed 400 grams (quite a lot to carry for a drone) and it was hard to maintain. The redesigned 3D printed exhaust (in same picture above on the right hand side), was 1 part – no assembly required. There were additional benefits: the redesigned part is quieter because of a different exhaust direction, it has wrench access which makes assembling it into the drone easier, and it offers greater efficiency because it was designed not to interfere with the air flow from the propeller enabling more thrust with the same amount of engine output. As in the piston example, here too the part is lighter: 25% lighter, shaving 100 grams off the part weight. Finally, it allows for easier maintenance thanks to a dedicated cleaning and maintenance access point. A lot for just 1 part redesign – that’s what makes it cool to me! This redesign was also serendipitous since, in spite of Cobra’s engineers’ AM experience, they hadn’t intended to use AM for this part and only considered it thanks to the available time during COVID-19’s related slowdown. This only goes to show that AM can be even more useful than people think, even those people with AM experience…
3. It Sinks, Naturally
The final part I want to highlight is a category of parts (and a specific one) that are perhaps less glamorous but are important for sustainability: heat sinks for electronics. Why are these strange looking, esoteric parts important? Cooling down processors is one of the most important tasks when we think about sustainability. We all know that we can reduce our carbon footprint by moving from physical to digital (moving bytes rather than atoms) but data and data networks have one unfriendly effect – they consume electricity. In fact, according to Nature, in 2018 1% of the world’s electricity demand was by data centers – this is 200 terawatt hours (TWh) a year – and that percentage is expected to rise sharply in the coming 20 years. One of the main reasons for energy consumption is the need to cool processors in all these data centers. It is a triple whammy: electricity is used to power the processors’ processing but also, as a side effect, some of the energy is converted to heat and more electricity is used to get rid of this heat. This is where heat sinks come in. With efficient heat sinks processors heat less helping them perform better and saving the energy needed to get rid of the generated heat. AM is particularly well suited for heat sinks as a heat sink dissipates heat through its large surface area – complex geometries can create very large surface areas. These heat sinks can apply to all kinds of chips, whether processors or LED chips so applications go well beyond data centers.
There are many heat sink designs but one of the latest (pictured above) was submitted for a heat sink competition sponsored by GE. This design was created by PhD students Soumya Bandyopadhyay, Julia Meyer, Adeline Naon, and Saeel Pai from Purdue. They used iterative topological optimization with the intent of not only maximizing the surface area but also the time air spends in the heat sink so it can take as much heat as possible with it. The students explain their design process and the inspiration: sharkskin. Sharkskin has a special texture which is made of millions of microscopic spike-like projections called denticles. Each denticle plays its part in reducing drag so the shark is able to swim with less water resistance. A similar mechanism ensures air mixture in the heat sink improving the performance of the part. This combination of an important application and inspiration from nature drew my attention so much that I overlooked that this part is just a prototype at the moment – it’s been tested for the competition but not in real life – hopefully it (or a variation of it) will be produced in the future.
Whatever your inspiration, I hope you can see what design for additive manufacturing can do for the next part or assembly. I’d love to hear your surprises from AM.