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Bubble-Infused Plastic Could Help Make Ford's Cars 750 Pounds Lighter

The MIT-developed technology, called MuCell, makes plastics super strong but extra light.

Here's one thing that often gets lost in the shuffle when debating the sexier points of green transportation: the simplest way to make a car, plane, whathaveyou more eco-friendly is just to make the whole damn thing lighter. All well and good, but how do you make sure that those industrial-grade plastic parts maintain their strength once you lighten them up? A technology developed at MIT called MuCell, and now being explored by automakers like Ford and Cadillac, has an answer. And that answer is: just add bubbles.

No, seriously: adding tiny bubbles of nitrogen or carbon gas into the normal injection-molding manufacturing process results in plastic that's just as rough-and-tumble, but up to 10% lighter (according to estimates from Ford Motors, who's very keen on using the technology). But wait: how does removing material from the part with these bubbles not make it weaker? The truth is that designers always massively "over-spec" the mechanical tolerances for these parts — usually 50-100%. So the relatively small reduction in material strength introduced by the bubbles is negligible, because the part was designed from the get-go to be much stronger than it'll ever need to be in practice.

Ford hopes to use MuCell plastic in all its vehicles by 2020.

Still, that 10% weight reduction could help Ford meet its goals of eventually shaving off anywhere from 250 to 750 pounds from an average car. Ford is hoping to incorporate the MuCell-made plastic into all its vehicles by 2020. Luxury brands like Cadillac are circling, too. So why are they suddenly interested in MuCell's microcellular foaming technology, which was actually invented nearly two decades ago at MIT before being commercialized by Trexel? Two simple words that matter now much more than they did in 1995: "Sustainability initiatives," says Levi Kishbaugh, VP of Engineering at Trexel. "Automakers like Ford have sampled the MuCell process over the past decade and have achieved good results, and now they are taking the next steps toward widespread adoption." Kishbaugh says that when MuCell is incorporated into part design and mechanical tolerances from the get-go (rather than applied downstream in the process), even greater weight reductions can be achieved while maintaining part strength: "20% or even more in many cases."

Bonus: Not only does MuCell result in weight-optimized designs, it also uses less manufacturing material too. (Bubbles are mostly empty space, remember.) This isn't to say that car manufacturers should give up on next-gen battery technology and other gee-whiz green engineering initiatives. But the small stuff — like zillions of microscopic nitrogen bubbles in a Ford manufacturing facility — matters, too.

[Top image, of soap bubbles, by Woodley Wonderworks]

[FC Top feat image, of Bubbles, by Thales]

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  • Greg Banyay

    What about using this same porous media to actually store hydrogen gas? A structurally sound outer shell could be fabricated to reduce the risk of disasterous accidents, weight savings could be realized in the vehicle, and a conformable structure could store they hydrogen gas that takes so much volume for a given mass thus helping solve some of the on-board storage issues. This was proposed to the industry back in 2005/06...

  • Mark Hollingsworth

    Interesting. Anybody know how much lighter one can make a car by shedding the big ole' combustion engine in leu of an all electric (Tesla)?

  • Luke Nieman

    How about adding a lighter-than-air gas instead of nitrogen or carbon? Hydrogen? Nope-flammable, car wrecks would severe. But helium would work. The tiny amount that would be sealed in the plastic would have a small impact on the weight of the car, but it would still make the car that much lighter.

  • Brett Johson

    Structural foams have been around for decades, and provide great strength at much lighter weights. They also provide for lower tooling costs because of much less mold pressures. Challenge however, is that they're aren't particulary aesthetically pleasing, especially for interior panels, and could require additional painting, parts or insert molding to achieve the desired aesthetic surfaces, processes which typically inhibit recycling. Your small net gain in of fuel efficiency are likely offset significantly when studied under a full life cyccle analysis.

  • Blain Rempel

    That's a very interesting approach, but I question the math on the weight savings. The MuCell technology would save 10% (or up to 20%) *of the weight of the plastic components* - to achieve a 250 pound savings that would mean 2500 pounds of the GVW is attributed to plastic parts, and I'm sceptical of that. I'm not suggesting it isn't worthwhile, just that the gains may be overstated.

    I'm also curious as to the overall affect on vehicle safety - while the individual components may still be structurally sound, basic physics would indicate that a lighter car is less safe than a heavier car in a head to head collision (more mass = more energy that is transferred and needs to be absorbed by the lighter structure).

  • Brett Johson

    Just running some quick math and I'm a bit puzzled over the claims. An average US passenger car is just under 3,000 lbs., most of which is comprised of metal, glass, and rubber. So even if give a generous estimate of 20% of the car weight in plastic, at best we'd realize a weight savings of approximately 60 lbs. (?)

    Still a great goal, but probably just a small fraction of the savings claimed.

  • Rachel Cheeseman

    This is really interesting, but I'd like to pose some follow-up questions if you'd be interested in satisfying my curiosity!

    What does this weight difference potentially mean for fuel efficiency? I'm assuming that's the primary benefit in having a lighter car, correct?

    What are the weights of different cars currently on the market? How many miles to the gallon do they get, and how would that change if they were 10-15% lighter? What about for hybrid vehicles?

    Reach me on Twitter! @wilycheese :)