Best Injection Material for Snaps?

Hi:

We have a small plastic part that was just tooled and it has small locking snaps on it. The original call-out was for ABS, but I'm not too happy with the results. The snaps tend to stay "sprung out" slightly after the parts are snapped together. I am thinking about trying a different material than ABS that would hopefully respond better to the bending and return to the molded shape.

What about Nylon/6 or 6/6 or Polycarbonate? This is a small part, and the dimensions of the snap barbs are posts about 30x60 mils, about 150mil long. They are deflected (bent) about 50mil out when they are engaged.

I guess a resin with better memory or flexure strength than ABS would be what I'm after. I think the ABS is stressed too far and not returning to the molded shape after being deflected.

Any advice from you molding gurus out there?

Thanks, Chris.

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chris_s
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I've used ABS before on snaps and it worked fine. But this part is very small, and the snaps are also very small. Did not have much control over their size due to other restrictions on the part. I think I will try Nylon

6/6. Acetal may have too much shrink. Nylon should have the increased resilance over ABS to do the job. The snaps only get used once.

Chris.

ABS is about the worst resin for snaps you could have chosen. Most amorphous (low shrinking) resins will perform poorly.

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Chris_S

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