I'm making a plug and mould for a small production run of parts and I've always used polyester tooling gelcoat and resin. Someone said epoxy tooling holds up better and stays truer, but it's a big step up in cost for a mould I might only use a few dozen times. Worth it?
For a mould that will only see a few dozen pulls, good polyester tooling resin and tooling gelcoat are usually perfectly adequate, and they keep the cost sensible. Epoxy tooling earns its price on moulds that need to hold tight dimensional accuracy over a long production life, because it shrinks less and resists heat distortion better, so the tool stays truer pull after pull. The other factor is what you are moulding, since an epoxy part is generally taken off an epoxy mould to avoid bond and release headaches, whereas polyester parts release happily from a polyester tool. For a short run of polyester parts a well-built polyester tool is the pragmatic choice, so reach for epoxy resin tooling only when longevity and precision justify it. Tell us the run size and the part material and we can point you at the right build-up.
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