Hi guys
I am having a hard time finding a temperature resistant and affordable mould material. My moulds will be huge (aircraft parts). I wonder if it is possible to postcure my wingskins or fuselage shells out of the mould. I aim at 100ºC postcure. Should I expect distorsions?
Depends on the resin system. We do our post cures out of the mold and the parts are fine. We use Tooling foam primarily as the molds, some aluminum. Then do a post cure at 212F, the larger parts like fuselage skins, are supported in a sling. Smaller parts right on the tooling table.
Thanks for sharing your experience.
What do you mean by tooling foam? Any example please?
Looks like supporting the pieces properly during cure could help to avoid distortions. I will take that way and build a large heating tent instead of heating every mold.
What do you mean by tooling foam? Any example please?
Do a search on “free standing postcure”.
First of all I am a bit surprised you are not able to source some high temperature resistant moulding material. Most polyester companies carry these materials, and usually are temperature resistant up to 80 degrees or so. I have worked with Reichhold, Nord and Scott Bader, which all work fine.
Once postcured inmould up to 80 degrees, there is usually not a big problem to postcure to 100 degrees freestanding. As long as you are able to control the temperature in your oven. I would suggest buying a PID controller for that, and a fan or 2 to mix the air in the oven. Make sure you control your ramp temperature. Ask your resin supplier for a maximum ramp. If not known, use 3 degrees / hour, which is very conservative. (so ramp to 80 degrees fast (20 degrees per hour, as that should be possible anyhow, then change to 3 degrees per hour until 100 degrees is reached. Keep it there for the prescribed amount of time.)
I mean tooling foam such as: https://www.generalplastics.com/fr-4500.html
there are several companies other than GP that manufacture it.
It works fairly well for shorter run parts
Freestanding postcure shouldn’t be any problem if you have a good resinsystem and a good temperature controller. The max is rising 10 C per hour but 5 is better. If the part is large as you say, make sure you suport it well and evenly.
Also finding a mold resin for up to 100 C shouldn’t be that big of a problem. Send me a pm if you need a supplier.