Lost Foam Core

I am working with a small part 8" x 5" x 2". I plan to layup CF over an foam core, enclose in a mold, heat and remove.

The part has no openings and there is no way to remove a core or mandrel. I do not care about leaving the foam core inside the part in fact I think this will give it more strength.

I have heard about EPS being used as a core.

Question is do I have to go to the trouble and high expense of having custom molded EPS core parts made, do I CNC some block of EPS? I don’t think machining EPS will yield very good results but who knows.

I like the idea of the EPS because as it gets heated it expands and provides inner pressure against the mold. Curious how much EPS would continue to expand if it was already in an expanded finished part?

Any other foam materials that would work in a similar way (expand, light weight, stay expanded and provide strength)but would be easier to work with?

I do something like that, and use PET foam.

Make a mould an cast what you want in 2 part A an B foam

Done that with cnc’d pvc foam, got some good results. Do a search for expancel here on the forums as well :wink: