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coleio
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Hi guys, so ive been searching for a supplier for carbon and carbon kevlar fabrics for about a month now and i have finally found one who meets my specifications for the latter mentioned materials. only problem is he only supplies fibreglass (which i need for mould making) in woven form. its really cheap in bulk so the price dofference doesnt bother me compared to chopped, but is it suitable for mould making? i think yes, but better safe than sorry
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Hanaldo
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Yes its totally fine. In fact I much prefer it, chopped strand is awful to work with. Cloth is very easily conformable, easy to cut, and stronger than csm. For epoxy moulds, I usually do 2 layers of 6oz cloth, then 2 layers of woven rovings. That'll be good for producing 10 or so parts.
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coleio
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ive priced for 200gsm chopped and they suggested 200gsm woven. i was planning on doing 6-8 layer of it. its incredibly cheap in bulk.
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coleio
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ok so i just heard back from the supplier. this stuff is only .1mm thick? is that normal? i only stated 200gsm as it is what was used in the bonnet making tutorial. would that do? how many layers do you thin i would need?
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coleio
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this is the stuff tey said they can do a thicker product, so would .5mm be best? or heavier? i want these molds to last for more than 10 go's.
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wozza
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For me the choice of resin and gelcoat is far more important than the choice of reinforcement when mould making. I use the uni-mould system from EC, good for 100 degrees and the gelcoat is hard and can be polished to a high gloss. I use infusion which is quite aggressive on moulds. I have had 50 plus pulls from some of them and they are still producing great parts. The repeated heat cycles during curing is what usually degrades moulds, that's why I think resin choice is crucial.
Regards Warren
Carbon Copies Ltd
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Hanaldo
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Yes I agree ^ I use Airtech Infusioncoat for anything that requires a post cure. Expensive stuff though. Coleio, it depends what gelcoat and resin you are using. If you're using epoxy, you'll be fine using heavier cloth as it won't shrink. If you're using a polyester or Vinyl ester system, then I like to use a couple layers of surface tissue as a print blocker, then build I think up in stages so a couple layers of 6oz, then a couple layers of 8oz, then your heavier cloths. For 10 or so parts using an epoxy tooling system, aim for around 4mm thick. If you're going for like 100 parts, I'd be aiming for 7-8mm thick. This is why I like to use 650gsm woven rovings, it's a good way of building thickness without having to use heaps of cloth.
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coleio
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thanks guys. im going to as them to custom order 600gsm. also i am still searching for resin suppliers, resoltech are my favourite so far as they do pretty high temp solutions. another thing, a supplier has quoted me for "A grade" and "B grade" kevlar cloth. they say that the b grade has "burrs" whatever that is, and it also has about 2.5% less strength (cant remember the exact technical data) and of course there is a price difference. do you think they are tryina pull a fast one on me?
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coleio
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oh, does anyone know where i might find the strength differences between chopped and woven fibreglass fabrics?
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ChrisR
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general rule of thumb is woven is 0.7-0.5x the UD strength (weave dependant) and CSM is about 0.3x then there is another reduction for fibre/resin ratio
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