Carbon Fiber.

[Guest timswait]

There's a wide range of different possiblities for processing Carbon Fibre. The best (as mostly used in Aerospace industry and F1) is pre-preg. Here the fibre is supplied pre-impregnated with epoxy resin (as woven cloth, or unidirectional) which has been half cured so it's tacky. This is then layed in a mould and cured in an autoclave (heat and pressure applied). This is clearly an expensive process, but it gives the best properties (low voidage, very even impregnation of resin).

It is possible to hand lay carbon though. You can buy dry carbon cloth (2-3 times the cost of glass cloth on average), lay it in a mould and roll in epoxy resin by hand. In this case you'd probably use room temperature cure resin (not as good properties as the high temperature systems), so no oven or autoclave needed. A vacuum bag will improve the properties, but they will be more variable and lower than pre-preg autoclave cured. It's also far more dependant on the skill of the laminator.

[Guest Jaffer]

I'm surprised that ABS is used at all .... its not UV stable, although the CF may help I guess...

[Guest Andy W]

I am using a mix of carbon fiber and carbon kevlar for the tunnel, tunnel top and internal side panel's, dash board and wind deflector. only £20 square meter used with vinester or epoxy resin, easly had layed up over / in MDF moulds as none of this is structual one layer of carbon can be layed up over glass cloth. When I get my camera back I will post a picture of what i have 'so far'

[Guest elwe]

If you lay the carbon fibre by hand do you get much of a weight/strength advantage? I would have thought the resin was at least 50% of the weight and if your laying by hand you are probably using the same resin and the same amount?

[Guest yosamite sam]

have you thought about looking for someone to make you a Cf part? there are people out there who do - i used to know someone who made canoes - cycle parts - etc and even a mini with his own workshop, dunno where he is now - but there will be others who will have small workshops... try not looking at car manufacturing try canoes etc - surf boarders someone will do it.. gonna be cheaper than buying one already done - if you can give them a pattern its cheaper still.

[Guest timswait]

If you lay the carbon fibre by hand do you get much of a weight/strength advantage? I would have thought the resin was at least 50% of the weight and if your laying by hand you are probably using the same resin and the same amount?

Hand lay up is the least good way of using CF, but it's still not bad. For a pre-preg laminate manufactured from unidirectional plies you can get up to 80% (by volume) fibre. For a hand lay up part you'd struggle to get 50%. Since the fibres bear most of the loads, the higher the volume of fibres the better. Also hand lay up resins are inferior to pre-preg resins (due to need to cure at room temperature) and the bubbles you invariably get in hand lay up parts degrade properties. You can see why F1 teams don't manufacture their chassis by soaking fabric with resin from a bucket and a sponge.

Having said all that a carefully made hand layed up CF panel will easily match an aluminium panel for stiffness and strength to weight ratios (probably exceed in bending) and will be far better than the chopped strand mat hand layed up glass reinforced polyester which RHE (and most kit car) nosecones are made from.

[Guest Kim]

My company currently makes replica parts for F1 teams in carbon (steering wheels, Wings, Full size Nose cones).

 

You do not need an auto-clave just a good vacuum pump and reliable commercial oven to cook the parts as the ramping of the temperature is quite critical.

 

The moulds need to be able to take temperature up to 80' C for low temp cure and 120'c for most other resin systems. We do have a good system (paste laminate) for putting on to existing parts to make moulds when the existing tools are not available.

 

The laying up of the pre-preg carbon is quite time consuming and then you have to make vac bags etc. not very cost effective.

 

Carbon is set to rise in price dramatically as there is at present a world shortage caused by Boeing buying up stock for the next 5 years.

 

Most other Carbon replica parts are just vac formed ABS not very realistic and have an acrylic top layer bonded to them which is not very UV stable mostly used for making throw away parts.

 

Some laminating company’s will wet lay up carbon to give the appearance of a superior product but most of these are polyester resin so try looking for epoxy products.

 

May be I am missing a marketing opportunity here

[Guest Andy W]

If you want to use carbon and are not after the lightest / strongest layup then hand layup is easy, I always cover the item with a thick plastic sheet and use a piece of nylon 'squegee' to remove the excess resin it also leave a smooth shiney surface on the inside.

One of my mates builds high performance Kayaks which are used by the top canoeists, all his boats are hand layup but he does use a vac bag. finished weight 12lbs strong enough to put one each end on a chair and stand in the middle. The trim pannel I have made just sit there and look nice. Strength and weight is not that important and only a little heaver than prepreg.