Hey guys I was wonder what is your thoughts about material for building moulds.
For none carbon fiber works I used vinylester gelcoat and polyester resin.
For carbon fiber I used epoxy gelcoat and epoxy resin.
I was wonder wheter it would be a good idea to build mould from epoxy tools ( as they hold geometry) just 2-3 layers of glass fabric and then use polyester resin with fiberglass to build up thickness and make mould more stiff.
Anyone tried in that way?
Poly will not stick to epoxy.
Most VE/low shrink tooling resin systems out there are fine for carbon work. Shrinkage will not be noticeable, maybe 0.2mm on something the size of a bonnet.
Indeed. Unless you are working with very narrow tolerances, polyester/vinylester tooling resins are fine. They hold their shine much better, and are easier to repair.
They are limited in heat tolerance, though, so if you go high temp, you might need an epoxy tool.
Good you point that , Im thinking about moulding car bonnet, so I think the mould itself should be resistant to heat for around 70 celcius degrees, as I want to put infused part inmould to oven, otherwise I think the bonnet will deform on very sunny weather and will be soft and lost stiffness
I mean putting fiberglass mat and polyester resin
over cured epoxy laminate (mould) for stifness
I heard you the first time. It wont stick. After going in the oven, the two will separate so easy, youll think it was released. Just so you know what I mean, put a bit of polyester resin on various surfaces (metal, glass, plastic) After it cures, you can just lift it off. Polyester is by not a glue, not even a crap one.
70 degrees is pretty low temp, in the whole scale of things. I do it like this:
Gelcoat: Nord GC206, Crystic 14pa, DSM Neogel (Nord is the better one)
Skin: DSM Atlac 580 Act, AOC Vipel F010 (this one isnt critical as long as its Tg is enough)
Tooling Resin: CCP Optimold, DSM Neomould, Nord RM2000, BUFA Tooling System (whatever is available in your country)
Can I vote for Nord RM3000 as well? Tg 110 degrees. (RM 2000 has 85 degrees)
Ok cc thats informative , gelcoat and tooling resin is obvious but what do you mean by “skin” ?
btw. do you reinoforce your moulds with fiberglass mat or glass cloth?
I allways use CSM when making moulds with a styrene based resins, its cheap and easier to consolidate (I find).
The skin layer is the first fibreglass layer after the gelcoat. Its not necessary but it prevents print through from the reinforcement layers that follow. Usually it is a lightweight layer of glass, so that it can conform to corners easier, but also so that it doesn’t print through itself. Its usually VE so that it makes a good bond with the gelcoat, but also acts as a latch for the polyester, as its a bit runnier and its styrene levels will be higher than the gelcoat.
Here’s an example:
Gel (GC206):
Skin (AOC):
Reinforcement (Optimold):
The first couple of moulds I made were scrap, as I didnt consolidate the skin enough and I got air entrapment in the corners. It wasnt obvious at first, but once heated, the pockets blistered.
Make sure you are working at least at 20 degrees C.
The other thing I recommend is to have your reinforcement layers cut and ready to go. Each manufacturer is different (Neomold is 4x450g, Optimold is 5x450g), and have your resin for each layer weighed and ready to be catalyzed in its own cup. The amount of resin will seem like alot, (between 3-4 parts resin to 1 part matt), but it has to go on there, otherwise it wont exotherm. And on the back of exotherming, you need to work fast. Make sure you measure the catalyst accordingly so that you have enough time to finish before it starts to heat up.
If you use RM3000 like herman recommended, you dont have to worry about exotherms or thickness, but its a VE based tooling resin and will be more expensive.
Optimold is good for 100C. Neomould says its Tg if 80, but Ive taken it to 100 consistently. For a bonnet, you’ll want to have a pretty thick mould, so 2 runs of Optimold will work. Unless youre only doing one part, in which case I would only do 1 run.
Any products similar to Unimold available in the USA? If so, from who?
Easiest place to buy from in the US is www.uscomposites.com if you’re looking for a mold that’ll be used in room temperature scenarios. Here’s a link to their polyesters page: http://www.uscomposites.com/polyesters.html. The easycomposite’s unimold system is just a polyester tooling gel coat and then a PE tooling or layup resin for the reinforcement layer. To avoid print-through you can just use very light layers of glass for the first one or two reinforcement layers after the gel coat. Using a light woven fiber glass (e-glass) instead of CSM in those first layers well help too.
Does anyone know if easycomposites mixes their own resins? Or do they just repackage and rebrand bulk stuff in retail quantities?
I think the uni mold and Opti Mold and others like what Nord makes are different than that, they seem to have a filler in them and they are supposed to be non shrinking,
Just wondering if anything similar is available in the US
Nord Composites (RM2000, RM3000) are available from Nidacore in the USA.
Cc that looks like a baking pan! Cooking carbon cactus cookies?
How do you feel about Hydrex100 VE resin?
Hardly available in Europe.
I imported several barrels long, long time ago. However, there are other VE resins with similar properties but less marketing available in Europe, so hardly worth the hassle.
But would you agree that Hydrex 100 is quite the quality product? I use it for everything that isnt infusion. EVERYTHING!
Also, could the whole, “polyester wont adhere to epoxy” talk be the reason why when I spray duratech on my parts it never cures over the epoxy filler between the seams of the parts?
Hydrex indeed is high quality. But there are others with the same quality.