When using epoxy or polyester for molds ?

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When using epoxy or polyester for molds ?

When using epoxy or polyester for molds ?

Author	Message
Zorongo	Zorongo posted 10 Years Ago HOT Topic Details
Group: Forum Members Posts: 40, Visits: 330	Hi all. I'm making small size epoxy parts, but sometimes I've made them whith polyester. Room temperature curing, hand lay up with small presure over the laminate (counter mold) I had demolding problems with a polyester mold and someone told me a "rule of thumb": Use polyester molds for polyester parts and epoxy molds for epoxy parts. (I'm actualy using PE molds for epoxy parts without any problem) So, the question is: Whe should I use epoxy molds ? An epoxy mold seems to be better fron the dimensional stability point of view.. It also seems logical to make the molld similar to the part if high temp increases are expected (prepregs, exotherms ?) to reach a similar diatation / contraction on both and avoiding stresses.... Could you please share your experience ? Thanks in advance
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Replies
biker_kev	biker_kev posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 5, Visits: 85	Hi, Your post shows you have had first hand experience of why you use epoxy tooling for epoxy mouldings and polyester tooling for polyester mouldings. If you mix the two resin types you will have great trouble demoulding your parts, to the extent you will probably end up scrapping them. Regards Kevin
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Matthieu Libeert	Matthieu Libeert posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 955, Visits: 3.4K	here are some tips and tricks I can give you. polyester wont stick to epoxy (low) epoxy will stick to polyester (hard) epoxy will stick to epoxy (medium) polyester will stick to polyester (medium) So If you apply this on a mould: Epoxy mould with polyester part OK polyester mould with epoxy part NOT OK BUT! if you postcure your polyester moulds and give them some time to let them evaporate the styrene and use some good release agent or in this case even better PVA you should be ok with it. polyester moulds are cheaper to make, can use chopped strands but are less stable at higher temperatures and will have more shrinkage. Vinylester gelcoat is a good alternative, compatible with epoxy and polyester sure other might correct me, or have some more information Matthieu Libeert Founder MAT2 Composites X Sports website: www.mat2composites.com
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