http://www.topgear.com/uk/car-news/lexus-l...llar-2009-10-30

I looked around and can't find much information on this way to manufacture composites. It looks just insane but I am curious why Toyota went to the expense to do this for a street car even though it is one amazing car.

Autoblog covered this too, and they said that there are only two machines capable of weaving carbon fiber.

Can this be true?! I thought Mercedes used a similar process in making the crash cones for their beloved SLR, so they must own the other machine? Why are their only two such machines, are they modified from now obsolete old cloth weaving machines or built to custom orders (and the demand is not there)?

Nice to watch, but not exactly new - the rope-manufacturing world has been using machines like this almost since the dawn of the Industrial Revolution.

Just for the A-pillars? Blimey.
Never know, they might have a fleet of these things knocking out parts for Toyota Echos in a few years time

Tony Matthews, but then Autoblog said this:



So there are only two of these 'rotary weavers' in this world?! If they are (were?) used for making ropes surely they wouldn't be so rare?

http://www.nfb.ca/film/how_do_they_braid_rope/

Primer, I hope I didn't sound dismissive, it's just that I have seen these machines in action, they are mesmerizing, all those bobbins tracing their intricate paths - I hope the link works, otherwise try Wiki

Not at all, I had a fair idea about braiding wire and ropes. It is this claim of only two machines in existence that is interesting. Now, Autoblog editors don't have the brains to think for themselves so they must have been fed this by Toyota PR. I don't think Toyota would lie about this. Perhaps it is a technicality: weaving vs braiding.

There may well be differences in detail, but the principal, I think, is the same. Carbon fibre rather than nylon/polyamid, and a different 'dance' of the bobbins. I bet it looks great close-up, as a finished carbon item.

PS. What about woven carbon prop-shafts?

I don't think that they would look any good on the A-pillars.

Probably function better than an A-pillar as a prop-shaft.

Cool. I guess the technology isn't that great or they'd be using it to fab parts for their F1 racers

F1 with prop-shafts and A-posts! Welcome to DTM...

Prop-shafts are filament wound, not woven. Just spin the mandrel and wind the epoxy-wetted carbon tow on at carefully controlled (by CNC) angles. It's the cheapest way to fabricate carbon parts because it's automated and fast, hence "consumer" goods like prop-shafts. Also used for missle body tubes, etc. pretty much anything roughly cylindrical.

Here's a mandrel for a fighter jet engine intermediate section I worked on years ago... to replace a titanium fabrication. I never followed up to know if it was successful in tests or put into production. Note it's not round, and in fact has concave areas... control of (very light) tension lets the fiber lay down in the depressions rather than bridge across.



What I believe Toyota is doing is weaving a multiple layer tubular preform (dry). Put it in the roof rail female mold with a bladder inside the preform, inject epoxy, inflate bladder, apply heat to mold... voila, a roof rail.
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