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Dentex
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Hy guys,
I was wondering did anyone maybe sucessfully made carbon moulding paste for high temperature moulds to use with pre preg? Like chopped fibers, some fillers (aluminium?) and high temp. epoxy? Or maybe just mix "virgin" chopped fibers and high temp epoxy to fill all the grooves and stuff?
It would go on EC high temp gelcoat and little print through is not a big problem because I will spray clear coat later on so surface finish doesn't have to be perfect.
I have fairly complex plug to make mould of and would highly benefit if I can use paste instead of fabric to make mould. Actually I would cover it with paste, get it as square as possible and than cover with fabric to add stability.
I would like to avoid fiberglass paste because it would be multiple - run mould that requires dimensional stability and object is long and not very wide (approx. 130x10x4cm)
Also, if this is not possible, does anyone have experience with carbon non wovens as first or first few layers on complex moulds?
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Warren (Staff)
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The EMP160 moulding paste is a similar material and can be used for the whole mould reinforcement for smaller moulds. We often see it used and recommend its use for filling in fine detail and corners after gel coat application where laying on fabric may be difficult to conform without bridging.
Warren PenalverEasy Composites / Carbon Mods - Technical Support Assistant
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Dentex
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Group: Forum Members
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+xThe EMP160 moulding paste is a similar material and can be used for the whole mould reinforcement for smaller moulds. We often see it used and recommend its use for filling in fine detail and corners after gel coat application where laying on fabric may be difficult to conform without bridging. Thanks for reply Warren. I understand that your product can be used both ways, but my main concern is dimensional stability due to different thermal expansion of fiberglass and carbon. My mold needs to be as stable as possible because there is a center line guide that needs to be straight as possible.
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Hanaldo
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Yes I've done it, it's as simple as it sounds. Make sure to weigh everything so you keep track of how much hardener you need to add. Mix your fibres into the resin before adding any filler powders so that the fibres wet out nicely. You can vary your recipe to get the properties you are after, but remember that when you add the hardener everything will get very wet again, so you want to make your initial mix extremely dry. It's been awhile since I did it, but from memory I used something like 10% fibre, 300% aluminium powder, 2% fumed silica. All as parts by weight of your measured resin before adding hardener. So if you used 1kg of resin, then it's around 100g of fibre, 3kg of aluminium powder, and 20g fumed silica. Try something along those lines, and fine tune it as you go.
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Dentex
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Group: Forum Members
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+xYes I've done it, it's as simple as it sounds. Make sure to weigh everything so you keep track of how much hardener you need to add. Mix your fibres into the resin before adding any filler powders so that the fibres wet out nicely. You can vary your recipe to get the properties you are after, but remember that when you add the hardener everything will get very wet again, so you want to make your initial mix extremely dry. It's been awhile since I did it, but from memory I used something like 10% fibre, 300% aluminium powder, 2% fumed silica. All as parts by weight of your measured resin before adding hardener. So if you used 1kg of resin, then it's around 100g of fibre, 3kg of aluminium powder, and 20g fumed silica. Try something along those lines, and fine tune it as you go. Thank You very much Hanaldo. Plenty of great info from you as usual. Can you please tell me, when you say fibre, do you mean like chopped carbon fiber od fiberglass?
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Lester Populaire
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+x+xYes I've done it, it's as simple as it sounds. Make sure to weigh everything so you keep track of how much hardener you need to add. Mix your fibres into the resin before adding any filler powders so that the fibres wet out nicely. You can vary your recipe to get the properties you are after, but remember that when you add the hardener everything will get very wet again, so you want to make your initial mix extremely dry. It's been awhile since I did it, but from memory I used something like 10% fibre, 300% aluminium powder, 2% fumed silica. All as parts by weight of your measured resin before adding hardener. So if you used 1kg of resin, then it's around 100g of fibre, 3kg of aluminium powder, and 20g fumed silica. Try something along those lines, and fine tune it as you go. Thank You very much Hanaldo. Plenty of great info from you as usual. Can you please tell me, when you say fibre, do you mean like chopped carbon fiber od fiberglass? Hmm I'd tend to trust what hanaldo says, however, it is usually not a good idea to mix in fillers to unmixed resins. This is especially true for fumed silica that has a humongous surface area per weight. This will wet the surface and then inhibit proper mixing on a molecular level. I'd recommend mixing resin and hardener first, then adding fillers.
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Warren (Staff)
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Some fillers like fumed silica really benefit from an extended soak period before using the resin to get the most benefit from the filler which means you cannot do it after the hardener has been added due to limited pot life. Pot life also often limits the ability to do that with other filler materials.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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Lester Populaire
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Group: Forum Members
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+xSome fillers like fumed silica really benefit from an extended soak period before using the resin to get the most benefit from the filler which means you cannot do it after the hardener has been added due to limited pot life. Pot life also often limits the ability to do that with other filler materials. So i just went down a deep rabbit hole trying to find some solid information on the topic and couldn't really find much, but from what I have seen i was wrong on the "do not mix into one component". Don't remember where i got that from, but just disregard my comment from earlier. Turns out one can trust Hanaldo after all 
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Warren (Staff)
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Hanaldo has a lot of experience and is rarely wrong in our experience!
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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