Apprentice at work has been given an assignment by college on the use of carbon fibre in racing bike frames. Couple of the questions he needs to answer is:

What are the Eco credentials of carbon fibre? And what kind of costs in terms of time and money does a carbon fibre frame take?

Any info most welcome please

Apprentice at work has been given an assignment by college

This is a great source of info.

^ that’s helpful 🙄

Eco credentials – in all honesty they are terrible. Recycling is pretty much limited to grinding up and stuffing it into something as a filler. Or you can acid digest or burn off the epoxy. Uncured waste is a little easier to reprocess, think of it as making an outfit from cloth – you always get some off-cuts from the fabric with traditional cloth methods. I might be a touch out of date on this so some searching on key points might yield some good news.

the area where CF makes back it’s eco credentials is in the reduction of in use energy. Eg a plane that has lower fuel burn due to being lighter. This argument doesnt really work for a bike, especially if the rider is fuelled by ethically sourced cake and is using it as a mode of transport not for sport and recreation.

Cost – bike manufacturing is labour intensive, unlike something like an AFP wing spar or skin which needs a £10M machine. For material costs look up the weight of a frame and then the cost of pre-preg materials (ie cloth with the resin already on there but not cured) as this is what most will be made from. Don’t forget to add a wastage factor and also plenty for consumables – tapes, vac bagging etc and energy for vacuum pumps, ovens etc. Labour I can’t help with as I don’t deal with that aspect.

The consumables also raises a good point of eco credentials as there is historically a LOT of waste from composite manufacture. Protective plies on pre-pregs, vac bags, vac tape, tacky tape, cleaning solvents, release agents etc etc. Re-usable silicone bagging cuts this a lot but still has finite life, as do the tools (moulds in laymans terms) which can be anything from composite, foam blocks, aluminium through to Invar (used in aerospace and very expensive but long lasting).

Maybe fire off an email to these guys in Bristol as they might have a document they can de-sensitise and send over to help: http://www.arrox.com/bikes/

Is the manufacturing process of the fibres itself less energy intensive than mining and transporting ore then smelting it? Cold forming the frame is probably less energy intensive than rolling tubes and welding the frame.

Is the manufacturing process of the fibres itself less energy intensive than mining and transporting ore then smelting it? Cold forming the frame is probably less energy intensive than rolling tubes and welding the frame.

Not sure about the first bit (transport and initial processing), but a lot of steel and aluminium is made from recycled base stock which gets used again and again and again. The energy for this can (sometimes) be renewable. E.g. hydro aluminium plants in Norway and New Zealand, Geothermal in Iceland (but that last one is a whole other environmental argument…).

I do some work with a cf manufacturer but in the aerospace/F1 sector, will see if they have any resources. I’m there tomorrow.

Carbon sequestration innit? How much more eco can you get?

Can’t you make anything carbon neutral by paying someone to plant some trees in a rainforest though?

Most quality carbon fibre filament is made from pitch tar left over from ‘cracking’ hydrocarbon for petroleum/diesel,etc..?

Good end use..

Don’t forget the manufacturing of the epoxy resin and toughening components, the manufacturing consumables. None of which are generally recyclable.

Some of the thermoplastic backing films are recyclable, also some changed to the latest resin systems have put a stop to the fibres being able to extracted and reused in other things as milled carbon.

There is a long way to go before we can get composites fully recyclable but I think we will get there. It is just going to be very different to what we use now.

I don’t understand why it doesn’t seem to be recycled more, for example a wheel or frame damaged, chip it up and re resin it like fibre board.. Ok not suitable for the same applications from a pure strength point of view, but you could make all sorts, garden furniture, general fixtures and fittings, cutlery handles, blah blah.

Does the college not want references? Somehow I don’t think this place counts

Does the college not want references? Somehow I don’t think this place counts.

I would hope this would be seeds for proper research not using comments here as the research itself!

I don’t understand why it doesn’t seem to be recycled more, for example a wheel or frame damaged, chip it up and re resin it like fibre board.. Ok not suitable for the same applications from a pure strength point of view, but you could make all sorts, garden furniture, general fixtures and fittings, cutlery handles, blah blah

That is actually a very good point, people often seem to think recycling means returning materials to the same grade/type of applications they were originally used for, but it doesn’t have to. Ground/crushed down as filler for a “lower grade” use would be a perfectly acceptable form of recycling IMO…

What actually happens to all the supposedly irreparable frames that get written off? I know at least some make their way to ebay as “spares or repair” listings…

“Eco-credentials” really have to be judged comparatively against existing alternatives, for the full life cycle of a given product.

So if nobody’s done the study already (and I bet they have) why not at least try to estimate the energy use of producing a composite frame from oil out of the ground right through to landfill/recycling vs pulling iron ore or bauxite out of the ground, through processing and fabrication into a frame to its eventual binning and presumably smelting down as scrap for re-use/recycling… I reckon he’d score points for at least attempting it.
It wouldn’t have to be done in tons of carbon, it might be easier and more understandable if you simply totted up total energy use in KJ…

@fizzer

great reference to check out:

http://www.torayca.com/en/

http://www.elgcf.com/recycled-carbon-fibre-services/recycling-carbon-fibre

That’s one way of doing it

We also did a project called elcomap.And some parts are now used on production automobiles from thermoplastic work we did.

Honestly things have moved a long way from what’s on Google search at least two methods of stripping epoxy from carbon aren’t even on there doing a quick search

couple of pics of pre-recycled carbon here;

http://singletrackworld.com/forum/topic/the-carbon-fibre-rejects-bin