Is mold made out of pu casting resin with aluminum fill too brittle for bladder process using prepreg? What is everyone else using for bladder mold other than aluminum mold?
That’s a good question…
The only time I’ve done it other than a cnc machined aluminum tool, I made a mold from steel U channel and plate. I guess the cast mold like you made would probably work but with lower pressure. If you do try it, let us know how much pressure your mold would take before distorting or breaking. I would think that polyurethane would have a lot of flex.
Urethanes can be had in a wide variety of hardness from hard and brittle to soft and rubbery. I think the casting resin tingc911 is referring to is the former. It can be used with bladder type pressures if it is well reinforced and supported.
Would have to be well reinforced… to the point of using metal casket type outer shell maybe. I guess if distortion in the part isn’t an issue, then it wouldn’t need much… or on the other hand, just do lower pressure?
What is the HDT of the urethane casting resin? What temps do you need to get to to cure your prepreg?