Casting resins! 3

[karlw]

I realise that is not quite on topic for this forum, but I was hoping that someone might be able to suggest a casting resin that has a low exothermic output during curing. This is important as I am casting into a small closed silicone mould and I require maximum dimensional accuracy of the cast component, currently I am using a specific acrylic resin to form a thin shell in the mould as casting in one results in too much distortion due to heat generated during curing. This specific resin type is necessary due to the applications requirement for sub micron surface texture reproduction. So ideally I am looking for a casting resin of some sort that will allow me to cast the remaining volume in one with no distortion.
Any suggestions would be most welcome, even if it's just a for a more appropriate place to post this!

 

[Compositepro]

You need a low shrinkage resin. Exotherm is only one factor affecting shrinkage. Epoxy will generally give lower shrinkage than acrylics and polyesters, but all resins will benefit from the addition of fillers like silica powder which displace resin which shrinks upon cure. The inert filler also greatly reduces exotherm.

 

[berkshire]

Have you considered a Poly urethane resin.

http://plastics.informous.com/view/871-poly-optic-14-series-casting-resins?source=sic

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[karlw]

Many thanks for your replies, I shall look into it.

 

[shobroco]

Epoxies won't work for any appreciable thickness. Although developed for a different and specific purpose, Rotafix has some products that might work; just google them.

 

[unclesyd]

You might want to look at products from flexbar. I've used aton with good results all time. Nearly anyone who sell machinable was hastheir products or a very similar one.