I have just done a small piece of work concerning a subsidiary of Messier-Bugatti, not whoever makes the Veyron - VW is it? - but the descendant of Ettore's company, still based in Molsheim, making among other things aircraft undercarriage including wheels and carbon brakes, similar to the ones used in F1 and some very advanced (and expensive) road cars.
How are these discs made? I gather that the basic manufacturing process involves rough machining, but the discs then have to undergo further fine finishing and deburring and so on, even perhaps get surface treatments. But what basic material are they machined from, and how is that made? Is it some sort of fabric like brake linings used to be? Perhaps it won't be a mystery to one or two of you. I am all ears (when not all mouth that is :o}).
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Thanks billy. A very succinct description though. Could have done with some diagrams and photos.
Probably involves heat and pressure by the sound of it.
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>>Could have done with some diagrams and photos.<<
Sorry cant find any! - yet! but heresa bit more info, you were right about the heat! ;-)
These brakes are extremely expensive as they are made from hi-tech carbon materials (long chain carbon, as in carbon fibre) and they can take up to 5 months to produce a single brake disk. The first stage in making a disc is to heat white polyacrylo nitrile (PAN) fibres until they turn black. This makes them pre-oxidised, and are arranged in layers similar to felt. They are then cut into shape and carbonised to obtain very pure carbon fibres. Next, they undergo two densification heat cycles at around 1000 degrees Celsius. These stages last hundreds of hours, during which a hydrocarbon-rich gas in injected into the oven or furnace. This helps the layers of felt-like material to fuse together and form a solid material. The finished disc is then machined to size ready for installing onto the car.
Billy
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given the prices I assumed they were hewn from solid diamond.
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i think i'l stick to my ferrodo,s
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These brakes are extremely expensive as they are made from hi-tech carbon materials (long chain carbon as in carbon fibre)
And aircraft seem to have them in three or four-decker sandwiches at either end of each enormous bogie... I believe they get through them quite quickly too.
Thanks again Billy by the way.
Edited by Lud on 07/02/2008 at 18:58
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Just think how much embedded, er, carbon they contain ;-)
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Just a little bit of aviation history on the subject of carbon brakes. I believe Concorde used carbon brake units. To aid in the testing of these units a Mk2 Lightning was modified with similar units for testing purposes. We had great fun at lunchtime watching this aeroplane race up and down the runway at Leconfield and applying the brakes. Lots of noise and smoke.
Moving slightly on, in ~ 1972 two Harrier jets took off from a coal yard near St. Pancras station to race to New York, trying to break a record of some description. It would appear that they also managed to break a time to altitude record as well. The pilot of the above mention Lightning took umbrage at this and decided to have a go himself. Off went the belly tank and anything else to lighten the load and we were treated to sight and sound of a Lightning doing its level best to reach 10,000 feet in record time.
Happy days, just around the time they discovered that too much excessive G forces tended to cause the wing tanks to leak fuel onto rather hot engines and a few ditched Lightnings in the North Sea.
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Just a slight "correction" - the brakes on road cars aren't carbon but carbon-ceramic.
They're made from silicon carbide reinforced with carbon fibre. Basically it's made by first making a carbon disc (as described above). Then, silicon powder is placed in contact with the disc surface and heated to between 1400 and 2000°C under argon gas. The silicon powder melts, diffuses into the disc over a period of 3 hours, forming silicon carbide.
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