Can anyone give me the lowdown on vinyl ester moulds. I have been using polyester for my moulds that I have been making polyester parts from but when I read into vinyl I read it has zero shrinkage?
So when I produce moulds for infusion use with epoxy is it ok to use vinyl as the resin to create thick laminates for the mould.
What are the pros and cons
Experience.?
Thanks in advanced
Vinylester will have shrinkage. Pro’s are that it’s a bit stronger and has better bonding, and possibly a higher Tg too.
If you don’t use elavated cure tempertures normal polyester/glass qill be fine. For higher temperatures the expansion coefficient of the reinforcement fibre will be a lot more important. Preferebly the same fiber as the product will be used, to prevent the mould shrinking around the product. (It’s quite hard to demould then.)
I’m considering making a concave mold that will have a carbon part inside the cavity of the concave mold. Would it be alright to make the mold out of glass for such an application or would a carbon mold be preferred?
Vinyl ester has ~6% less shrinkage than polyester. Makes a difference when it comes to making parts where dimensional accuracy is important, shrinkage is a killer when it comes to achieving good vehicle panel gaps for example. Otherwise you should choose your tooling system based on how many parts you need to pull from the mould. A vinyl ester mould will last longer than a polyester mould, provided they are both made to the same standard. As for using the mould to infuse epoxy parts, that also depends what release system etc. you are using. A good semi-permanent release system will allow good release with both polyester and vinyl ester, but I would be cautious using wax/PVA with a polyester mould, I’ve had sticks before.
Personally, I much prefer working with vinyl ester. It isn’t THAT much more expensive than polyester, and I do believe it’s higher quality justifies the slightly higher price. These days I only use polyester for parts that don’t require precise fitment and I only expect to make 1 or 2 pulls.
My mould release system I use is tr wax ATM but I will be switching to a semi perm soon to try. It’s mainly panel gaps. I see there is polyester tooling resins but the price is triple that of normal polyester and some ask for a vinyl single layup before hand.
My main business is track focused body panels
Similar to me then. Personally, if I’m making any parts that require good fitment, I don’t even tell the customer that polyester moulds are an option. What it comes down to for me, is the customer will always expect the best result. To me it isn’t worth the risk of having a part stick (although I no longer worry about that with Frekote) or having bad panel gaps. So I work almost exclusively with vinyl ester or epoxy tools, with the occasional polyester when I get a one-off part where we aren’t worried about fitment or heat exposure.
So you are regularly using vinylester resin over poly. Is it just a standard vinyl or tooling?
My workshop is a constant 25 degrees c so when I infuse I dnt don’t have no problems. What determins for you to choose between vinyl and poly. For example I have a set of doors for my Gtir to mould. So apart from budget what would you choose. Also I never have done epoxy moulds so I wouldn’t know how thick to go is there a general rule of thumb for this ?
Poly is a no go for the first layer of molds in my opinion. I should choose for a vinylester over a epoxy. It’s cheaper, you can use a gelcoat and lett it shine like crazy. Also you can pull polyeser, vinyl and epoxy products out of a vinyl mold. You can’t pull polyeser or vinyl products out of an epoxy mold, or at least it’s a big risk.
You can’t pull polyeser or vinyl products out of an epoxy mold, or at least it’s a big risk.
I never had any problems with that. Epoxy out of epoxy or PE out of PE moulds can stick on chemical bonding.
Polyester tooling resin isn’t bad at all. Almost no shrinking, fast build up, easy and (relatively) cheap. It’s what most big company’s use for building moulds.
Only when using elavated temperatures I would change to VE tooling resin. Or when using stitched fabrics or unidirectionals, and carbon or aramids.
I had and my old supplier (Herman) told me also, but that can depend on what resins and release agent used maybe. I forget to tell that poly is a no go for first layer. First apply a vinyl layer, lett it cure and then use poly tooling resin to build up. I do it the same way. Sorry for the mistake.
I use a standard vinyl ester for the whole process. I blend my own tooling gelcoats using the same vinyl ester laminating resin that I use to reinforce the whole tool. That’s purely because of availability, vinyl ester and epoxy tooling systems are simply non-existent in ‘small’ quantities in Western Australia.
For doors, I would certainly be using vinyl ester. Door fitment is critical, so I would always use a vinyl ester system to build the tools.
This is a very good thread and I thank you all for input.
I normally make moulds that require a wet layup or vacum bagging (envelope) about 10mm thick sometimes with a coremat. So for said mould in epoxy how thick are you all going?
So from what this thread highlights is for good moulds cured at 25 degrees vinylester is a very good option compared to poly. And that’s for any layup method inc vac bag and infusion.
Choosing epoxy is mainly down to if it’s heated curing
Also (sorry for the winded replies) are you all using csm or twill weave glass for moulds ?
Vinyl vs epoxy depends on a few things. The vinyl ester I use can take 90 degrees which is enough for most things, and I’ve got some Airtech TMH5001 which can take 180 so I use that for engine parts etc. My main reason for using epoxy is if I have any doubts about the paint compatibility of the part I’m moulding and the styrene based tooling systems. Generally I use PVA on plugs, but occasionally I get a part with a perfect finish on it that I don’t want to use PVA on.
Mould thickness I do the same whether it’s poly, vinyl or epoxy. It depends how many parts I intend to pull from the tool, for 5-10 I am for 5mm, more than that I aim for 7mm. Bigger tools like bumpers and bonnets I aim for 10mm.
For poly and vinyl moulds I use mainly CSM, because it gives strength in random (all) directions. With woven cloths you have to consider the fibre direction etc. Normally I do 2 layers of 80gsm surface tissue, 2-4 layers of 225gsm csm, 4-5 layers of 450gsm csm, and on some moulds, 1-2 layers of 650gsm woven rovings.
Possibly because the styrene attacks the epoxy, most epoxy can’t handle that for long indeed without special care
And yes, So did I forget to mention, always a vinylester skin coat. I’s so obvious for me, but for others…
Also (sorry for the winded replies) are you all using csm or twill weave glass for moulds
Right now I’m building vinylester moulds at work, for autoclave use, with carbon and glass. No csm there.
But You can use csm, bit easier, no risk of distotion (different angles in the weave…), etc
Susho you using a vinylester throughout the mould. Or poly tooling after first layer
Currently all vinylester, infusing, reaching a high Tg after a lot less time post curing than it would with epoxy, and the ability to use a gelcoat.
Think I’m going to try a tooling gel. Vinylester and then a poly tooling gel on my next big mould that I will use for infusion. See how it comes out thanks for the advice regarding layup. Will keep this post running as I get 2 sets of doors to build in the next 2 months
as far as stating that VE is the be all end all it depends on whether it is a true VE which is a modified epoxy or if it is a modified Polyester variation. I have built plenty of moulds using poly,VE a combination of both or poly tooling / Ve tooling systems. I know of others that have have used low profile systems in autoclaves with prepreg carbon parts. fancy poly/ve tooling systems usually have a high ATH loading to help with heat and shrinkage.
The number of parts is really the key to how carried away the mould needs to be. There is no point in building a $10000.00 mould to make 4 $100.00 parts. take this into account.
I also build plenty of racecar parts. I struggle to see the sense in worrying too much about .05mm shrinkage when the rest of the car can be out by miles particularly by the end of the season.
I build large flanges and use steel framework for larger moulds or If I plan to build 1000s of parts.
I also have a bit of a theory on expensive materials. Sure, they have their place and if warranted I will use them, but I have encountered far too many people doing xxxx work with the best gear. poly is easy to use and all but idiot proof. keep an eye on catalyst levels, and resin content. it will last way better than a poorly built Epoxy mould.