By on October 17, 2013

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One of our readers, Noble713, commenting on a news items about the BMW i3, asked if TTAC could provide more coverage on BMW’s carbon fiber productions methods. The i3 EV, and upcoming i8, are built upon CFRP structures. Weight is the enemy of electric vehicles. The more weight you can take out of the actual structure of the car, the more battery cells you can carry for more power and better range, hence BMW turning to carbon fiber. It turns out that BMW has released a series of videos (bilingual, wait for the English) on that very topic. Their CFRP production uses materials made by SGL Automotive Carbon Fibers, a joint venture between the BMW and SGL groups and the effort spans the globe. SGL has expertise in carbon fiber and in 2011 BMW took a 15% stake in the company. Pure polyacrylonitrile fibers are made by Mitsubishi Rayon Co. in Japan and shipped to a state of the art SGL ACF factory in Moses Lake, Washington, where the PAN fibers are first oxidized and then baked into carbon. Wound on spools, the raw carbon fiber is shipped to a SGL ACF facility in Wackersdorf, Germany, were the carbon fibers are woven (actually sewn) into fabrics. The fabrics in turn go to BMW’s Landshut facility were they are laminated in the proper orientations, resins are added, patterns are cut and the finished parts are molded.

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BMW has been publicizing how environmentally sensitive their CFRP manufacturing is, stressing how the Washington state facility is powered by renewable hydro power.

While carbon fiber is regarded as almost magical stuff because of its superior strength to weight ratio and the ability to orient the fabric so the resulting parts are stiff in some directions and flexible in other directions, it is still relatively costly to work with, compared to aluminum and steel. Like the CFRP shop at Toyota’s LFA works, BMW is using carbon fiber for the i3 and i8 not just because of those inherent characteristics but also so they can develop processes for the inexpensive mass production of CFRP parts.

Ronnie Schreiber edits Cars In Depth, a realistic perspective on cars & car culture and the original 3D car site. If you found this post worthwhile, you can get a parallax view at Cars In Depth. If the 3D thing freaks you out, don’t worry, all the photo and video players in use at the site have mono options. Thanks for reading – RJS

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6 Comments on “A Look at BMW Carbon Fiber Production for the i3 Electric Car...”


  • avatar
    NMGOM

    Great. Now all BMW has to do is apply all that light-weight carbon-fiber technology to conventional small ICE cars with 3-cylinder turbo engines, and, voilà, you get 100 mpg and a 400 mile range without complex, expensive, rapidly depreciating technology. Might even allow a manual transmission….(^_^)…

    ————–

  • avatar
    LeMansteve

    To which fancy body shop does one bring their crashed carbon fiber-bodied BMW? Will this introduce new body repair techniques, or will it be as simple as bolting on a new carbon body panel and spraying? Surely insurance premiums will be high.

    The good news is, shops won’t be able to source some knock-off aftermarket body piece with an ever-so-slightly different fit.

    • 0 avatar
      Stumpaster

      Boat building shops can do the repairs. Better yet, you can custom fit the parts rather than rely on someone in China to be diligent enough to stamp your steel part with accuracy.
      But speaking of accuracy, carbon repairs require a bit more meticulous type than your typical bondo applicators.

    • 0 avatar
      hgrunt

      No doubt the cost of repair will be extremely high! High performance cars like GTRs, AMGs, Ms, are already high because they use so many low-volume parts. Strangely enough, Lotus Elise insurance is relatively low–no doubt because they’re only used on weekends.

      I think CF repair itself is, at a mechanical level, fairly simple. I read recently that the cars that Pagani uses for crash testing, they simply take the test car and bolt new subassemblies on. I think the same goes for McLaren F1s, Ferrari F50s, etc. Of course, the parts and labor cost will not be anywhere as trivial.

      Just like we worry about a shady body shop grinding down a bad weld on a structural part and painting it over, the worry with CF repair would be substandard materials or shoddy repair to structural CF. Composite body panels can be fairly simple to reproduce by some shady dude in low volume, unlike metal parts which require an industrial press and a giant die.

  • avatar
    Windy

    The video is two years old and the cycle times of the process looked slow to me in comparison to some carbon fiber construction I have seen used in yacht parts this last summer. I wonder how much faster that part in the video is being made today…. Cycle time has been the big problem in composit fiber construction for high volume production dating right back to the 50s and 60s which has meant that its use has in general been confined to either low volume products or small parts of higher volume autos…. Has BMW cracked this problem yet?

  • avatar
    3Deuce27

    There has been a lot of inane noise on this site about ‘game changers’, well, the BMW I3, is a game changer.

    And too risk even more guffaws from the rabble, so is the new Gen-7 Corvette. World class performance and build quality for a paltry $52,-$62,000.

    While I’m at it, I will add the new Cadillac CTS V-Sport to that short list.

    If I wasn’t still helping to fund the grand children’s schooling, I would add all three to my garage.

    Let it fly…….


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