Post by ridehpd on Nov 24, 2021 22:44:34 GMT -5
Hi everyone, I'm trying to cast some fishing lures in a custom aluminum mold I had machined but I'm running into a lot of problems with voids.
Across the board I'm using:
3 coats of the UMR (as recommended by Alumilite CS, need to try one of the urethane specific mold releases)
50 psi in pressure pot
Measuring on 0.1g scale, mixing for 60 seconds
I need to modify the vent design, but when I cast with the resin and mold at room temp I generate some porosity on the top of the lure along the mold seam, and large voids around the vents and gate where the resin appears to retract during pressurization/gelation (I pour excess resin into the gate to fill the little funnel machined in, approx 3-5 mL on top of 60 mL mold cavity).
When I fully degas each part separately (B by itself, A mixed with dye/pearl powder) I end up with significantly more voids than when I don't.
Finally got around to converting a toaster oven to preheat the mold, and after preheating to ~130F (127.5-139F measured by IR temp gun) I ended up with the worst pour yet, and approximately 10-15% density reduction from porosity throughout the casting.
Not sure what I'm doing wrong, although maybe still too much mold release, as I have had some issues with that here and there, spraying too much on for each coat.
If I can provide any additional information please let me know.
Eric
