> Is there an issue with "silicone migration"?

Don't know, but certainly not if you wrap the silicone plug with release film. The release will  help with filling the mold if the silicone plug is slightly too small to produce the required pressure, just give it another layer of release film.

Agreed with brainfart - I think the idea here is that even with widely different coefficients of thermal expansion, you need a LOT of temperature change to create a meaningful dimensional change. Given that, you'd likely need a very firm compaction around the male silicone part(s) to even get the whole arrangement into a mold. Sounds like a process that is good for banging out lots and lots of identical parts.

Thermal coefficient of expansion for aluminium is 22.2  (10E-6/K), unfilled epoxy resins are 45-65, most plastics are around 80-200 or so.

If you have a mold made from aluminium, fill it up completely with another material which has a larger coefficient of expansion and then start to heat the whole thing, the other material will expand faster than the aluminium and produce an enormous pressure inside the mold. So the whole trick isn't finding the right silicone for this (most likely the reason silicone is used is 1. its non-stick properties and 2. its heat resistance) the problem is rather being able to fill the mold completely without leaving too much empty room. I don't think you need a special silicone for this, standard material will work.

Is there an issue with "silicone migration"?

My parts need to have a secondary bond after they are cured.  One part glues to another.  I would hate to have silicone compromise this bond.

Otherwise I am really curious about trying the expanding silicone core.

For extensive knowledge on silicones, contact the Wacker distributor, in your case, MC Technics in Vise. I know they have a lot of knowledge, and can provide you with a lot of technical info, very probably also on expansion rate of silicone.

Forget about the intumescent stuff. Once expanded, it does not contract anymore, and it forms a very hard and brittle residue, which is insulating and fire resistant. Great for the purpose of fire protection, but not for cores.

Hi Matt

I know they went into great detail about the silicon expanding exerting tremendous pressure. That is why they had to put into a press. The details I read may be on their site and note in the article on composite world. Do some more searching.

Fred

I guess they wont ship a few Kg :p their should probably be a suplier in europe...

Matthieu Libeert
Founder MAT2 Composites X Sports
website: www.mat2composites.com

I got a reply that they dont have reseller in Europe, and they asked how much they should send by boat.
hm,,,

http://motoform.blogspot.se

Fred
Thats great, thank you.
I sent an email to their supplier now, lets see if the product is available in europe.

http://motoform.blogspot.se