Guidance on Epoxy molds

[cambria]

We have purchased an Arburg ALlrounder 35 ton injection machine, old but in beautiful shape. It has a MUD set (modular tool setup) so quick change with smaller subtools make this ideal for us. What I want to do is make a unit tool (basically a bath-tub for the epoxy) for epoxy molds. We do a lot of experimental work making sensors, so its smaller bits and pieces. I can make one of anything on our old Grizzly lathe and mill (dont ask for three identical parts) so I am hoping we can get a few good shots per epoxy mold. Any guidance out there on the use of epoxy molds? Decreased expectations on quality? Can we get a decent surface on the part? I think our largest piece would be only a couple of inches across.

 

[patprimmer]

What material will you be moulding.

I have seen excellent results from epoxy moulds inserted into bolsters, with up to 100 shots from the inserts.

The material was Cellulose Propionate in spectacle frames.

Higher temperatures or higher injection pressures may give poor results. I would not try it for PC or GF nylon 66 fr instance.

Regards
Pat
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[cambria]

Thanks. Thats good news, and 100 shots is fantastic. Well as it comes out, polycarbonate would have been a good candidate for some of our optical parts, and we use a lot of Delrin as well, which is a higher temp. But, considering the basis of this - protos - I should try to stick to my own rules and not try short production. Lets put the question around: what would be optimal materials for good finish, fluid resistance, strength and perhaps machinability be? Delrin has been very good to me, but your proviso seems to exclude it as a candidate.

 

[HDS]

Talk to huntsman (or whoever they are called this week.) They have design guides for epoxy injection molds. Freeman Supply may also have some information because they sell the epoxy.

 

[cambria]

Thanks, they have a lot of materials. DO NOT go through the front door at Huntsman, otherwise you get to know what chemical to treat your soy beans with, our how to invest in the company. Found better luck to Google Huntsman and epoxy molds, and received a waterfall of info. Thanks again.