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Ash R
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Hi. Quite new to composites, dabbled about a bit done lots of research online and bought some books, but after a couple failed moulding attempts I've decided to try a simpler project and reach out for help! Front winglets seem to me a simple project to make.  looking at making a pair similar to what's in the picture. I could get my hands on a pair of ali ones to take a mould from. I plan on taking moulds using the Uni mould kit. Need advice on how to get both sides cosmeticly pleasing. Mould of each face and bond together with foam core? Split mould designed to be a closed mould and used to compress the CF producing one piece straight from the mould? Just need advice on this before I start making the mould as would affect the design. Many thanks
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Warren (Staff)
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The simplest way would be a wet lay compression mould. In effect you are taking a mould of each side, wet laying in the fabric and clamping them both together. You want to make the moulds quite sturdy. You could simply fold metal as both surfaces look flat. You would polish highly and in effect "score" around the part on the surface to give a visible cut line.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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Steve Broad
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If the surfaces are flat I would do as Warren suggests. Make a sturdy mould of one side only and place a polished folded aluminium plate (treated with several layers of release agent) on the other side. Plate needs to be 4mm thick in order to prevent vacuum pressures distorting it. However, bending plate this thick may result in cracks along the outside of the bend and these will need to be sanded/filled. If you can't bend 4mm you will probably get away with using 3mm or even 2mm. on a small/thin item such as this. Update. Rethinking this, you could possibly make both sides of the mould out of 4mm aluminium. The only issue I can think of is the possibility of vacuum distortion but, with a total of 8mm thickness of aluminium this is unlikely IMO. The mould would be quick, cheap and easy to make. I recently made these aero deflectors (still to be cut to shape) out of 4 layers of 375gm prepreg carbon laid on both sides of a 1.5mm thick aluminium mould (thereby making a pair using one mould :-) ). 120 dec C curing and no distortion. I wouldn't bother with a core, just use more layers of carbon (6 layers of 2-300gm will be ample, probably get away with 4 with such a narrow piece.). Using a core means that you have to deal with the exposed edges (unless you can wrap the carbon around them which isn't easy). Using only carbon does away with this.  
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Ash R
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Group: Forum Members
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Thanks for your replies guys! The original pattern is 4mm ali finished in black powder coat.
From your advice I gather I could make two highly polished plates to compress the CF between, applying the pressure via clamps or a press.
Or
Make a mould of the outer face of the pattern using Uni mould then wet lay the CF and use the original pattern I used to make the mould as a plate then vacuum bag the lay up which will apply the pressure to the plate.
Thanks again
Update : so if I get two 4mm aluminium plates both with 90 degree folds in the middle, score round the pattern onto the plates to provide a cut line on the finished part, the sandwich these together in and envelop vacuum bag?
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Steve Broad
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Group: Forum Members
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+xThanks for your replies guys! The original pattern is 4mm ali finished in black powder coat. From your advice I gather I could make two highly polished plates to compress the CF between, applying the pressure via clamps or a press. Or Make a mould of the outer face of the pattern using Uni mould then wet lay the CF and use the original pattern I used to make the mould as a plate then vacuum bag the lay up which will apply the pressure to the plate. Thanks again Update : so if I get two 4mm aluminium plates both with 90 degree folds in the middle, score round the pattern onto the plates to provide a cut line on the finished part, the sandwich these together in and envelop vacuum bag? I would go with the last option. However, if you use plates much bigger than the part make sure you cut the carbon to cover the whole plate. If you don't the two plates will be pulled together where there is no carbon, thereby bowing them and reducing the pressure in the carbon area. Alternatively. cut the plates just a little bigger (5-10mm) than the shape you want.
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Ash R
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Group: Forum Members
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Visits: 61
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+x+xThanks for your replies guys! The original pattern is 4mm ali finished in black powder coat. From your advice I gather I could make two highly polished plates to compress the CF between, applying the pressure via clamps or a press. Or Make a mould of the outer face of the pattern using Uni mould then wet lay the CF and use the original pattern I used to make the mould as a plate then vacuum bag the lay up which will apply the pressure to the plate. Thanks again Update : so if I get two 4mm aluminium plates both with 90 degree folds in the middle, score round the pattern onto the plates to provide a cut line on the finished part, the sandwich these together in and envelop vacuum bag? I would go with the last option. However, if you use plates much bigger than the part make sure you cut the carbon to cover the whole plate. If you don't the two plates will be pulled together where there is no carbon, thereby bowing them and reducing the pressure in the carbon area. Alternatively. cut the plates just a little bigger (5-10mm) than the shape you want. Think I will look into this method then. Thanks for pointing out the issues oversized plates could have, wouldn't of thought of that. Do you think stainless steel plates work just as well as aluminium? I ask cause I could probably get my hands on stainless for nothing, maybe even folded and cut to size if am lucky.
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Steve Broad
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Stainless sounds like a great idea as it will be nice and shiny already :-)
One thing to take into account if you decide to go the prepreg route is the time taken to heat up the steel. If not enough time is allowed the resin next to the steel will not cure properly.
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Ash R
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Il see what I can get my hands on then!  Doubt Il be playing with pre pregs for a while yet but something to bare in mind. Am I right in thinking that the inner plate will have to be slightly smaller to accommodate the thickness of the first plate and the laminate? For example. ( measurements for example purpose in mm) Outer plate = 100 x 100 x 4 laminate = approx 2.5 / 3mm Inner plate = 93 x 93 x 4  This way when all compressed the plates will match up. Otherwise if they were the same size the inner plate would stick out by 7mm.
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Steve Broad
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That will make the mould neater but the overhang wouldn't cause a problem. Ideally the bend radius should be smaller for the inner sheet, so maybe use 5mm plate for outer mould and 3mm for the inner. However, the difference is so small it probably won't be an issue.
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