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[Jason Murray]

I’m planning to use vacuum casting to produce about 50 housing units with integrated snap-fit features for an electronics prototype. The parts need to survive multiple assembly/disassembly cycles during testing. I’ve seen mixed opinions on whether cast PU is tough and flexible enough for that kind of stress. What’s your experience—does vacuum casting hold up in real-world snap-fit use, or is it better to switch to another process for this kind of mechanical function?

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[jar_db]

Personally, I wouldn’t suggest using vacuum casting for snap-fits. I’ve used PU resins that are pretty flexible, but they just don’t hold up as well in repeated flex cycles as injection molded ABS or PC.  I’d rather go for CNC machining of Nylon or injection molding on this one.

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[Arjun]

From my experience, the snap-fits will hold up for about 20-30 cycles, and then you’ll start to see some microtears and reduced retention force. It’ll be okay for demo use, but not for heavy cycle testing. PU just doesn’t have the same fatigue resistance as thermoplastics.

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