Automotive Part 1

Your masterclass in product design and development

Our Insight video series will help you master digital manufacturing.

Every Friday we’ll post a new video – each one giving you a deeper Insight into how to design better parts. We’ll cover specific topics such as choosing the right 3D printing material, optimising your design for CNC machining, surface finishes for moulded parts, and much more besides.

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Insight: Automotive Part 1

Transcript

Hi and welcome to this week’s insight video. For the next two weeks I’m going to take a closer look at how modern production technology can reduce component weight in the automotive industry.

There are a lot of things we look for in a new car – the engine, the handling, the gadgets in the dash… However, over the past few years one factor has been steadily climbing in importance, both to consumers and manufacturers – fuel efficiency.

Sure, it isn’t exactly the most eye-catching stat you can have on a car, but higher efficiency makes a vehicle cheaper to run and cuts down on the amount of carbon it emits – both of which are incredibly important in our world of climbing fuel prices and increasingly stringent regulations.

There are a lot of ways to pump up fuel efficiency, but one of the best ways to do this is by simply reducing vehicle weight. Lighter cars mean less weight to lug round and less fuel burned, which is good for everybody.

Of course, things aren’t quite as simple as ripping out all the metal and replacing it with candyfloss. We still need our vehicles to perform well and be safe to drive, so we need to carefully modify the designs and see where we can make safe, sensible moves over to more lightweight products and components.

This means a fair bit of prototyping, where material and manufacturing process selection is vital.

Now, as you might have guessed, this is a pretty big topic to tackle all at once, so today’s video is going to be a two-parter. This time around we’re going to be looking at material selection, while next week’s video will be all about the manufacturing process.

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Right, so let’s get down to materials. Or, specifically, plastics.

You see, while it may not be the first thing that springs to mind when you think of high-quality car components, an extensive selection of glass-, metal- or ceramic-filled polymers as well as liquid silicone rubber – or LSR – can often be used to replace metal parts at only a fraction of the original’s weight. Today, we’re going to run through a whistle-stop tour of seven of the most common, and most useful, options out there.

First up, polypropylene. This is a flexible, fatigue resistant family of thermoplastics that are already commonly used in automotive interiors, battery cases, boat hulls, prosthetics and plenty of other products that need to be both tough and lightweight. There are a few different grades of polypropylenes, but copolymers and random copolymers are engineering-grade materials that offer superior strength-to-weight ratios and good impact resistance.

All polypropylenes are also heat-resistant, with melting points in the neighbourhood of 150 C and in case you ever feel the need to heat up last night’s leftovers in your car, are microwavable.

Next up we have polyethylene, which is offered in both high-density and low-density versions. The high-density has uses and mechanical properties similar to polypropylene but is more rigid and offers greater resistance to warping. The lower density I is more flexible, but both materials are suitable for use where toughness and low weight is needed – such as a glove box or a cold air intake.

ABS is another thermoplastic that has exceptional impact resistance and toughness. It’s already used on some vehicles as a lightweight alternative to metal in dashboard trim, electronics enclosures and hubcap covers. Indeed, the chassis of the world’s first 3D-printed automobile – the STRATI – was made of carbon-fibre reinforced ABS. Amazingly, the entire thing weighed just 499kg. If that’s not impressive, I don’t know what is.

Right, next up is polycarbonate. This material is very thermoformable, and is frequently shaped into see-through architectural panels, lenses for glasses, industrial computer screens, and other products where glass is unsuitable due to weight or breakage concerns. It has 250 times the impact resistance but only half the weight of regular glass – in fact, bulletproof glass and aircraft windows are usually made of polycarbonate or its slightly more flexible cousin, acrylic.

Nylon is the next material on our list. And we don’t mean that old jumper from the 80s.this material is frequently filled with mineral or glass fibres to improve stiffness-to-weight ratios and improve mechanical properties, making it one of the strongest plastics available. Because nylon is self-lubricating, thermally stable, and very wear-resistant, it’s an excellent candidate for sprockets, fan blades, gears, latches, manifolds and bearing surfaces. It’s also incredibly light, at just 15% the weight of steel and 40% of aluminium.

Next on the list is Acetal, more commonly called by its trade name Delrin. This is a regular go-to material for machined prototypes. It’s strong and stiff without the need for nylon’s glass-fibre reinforcement and is regularly called upon to replace precision metal parts in a range of industrial and consumer products such as gears, bushings, and bearings.

Finally, Liquid silicone rubber, or LSR, is an incredibly versatile material for many moulding applications. It starts out as a two-part thermoset compound, which is mixed at low temperatures and then injected into a heated mould. Upon curing, LSR becomes strong yet flexible, and is suitable for gaskets, lenses, connectors, and other parts that require excellent thermal, chemical, and electrical resistance.

And that’s it for this week! Make sure to check back next week for Automotive part 2. In the meantime, have a great weekend.

With special thanks to Natalie Constable.