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[May Hall]

I’m working on a small injection-molded housing for an automotive sensor, using PA6 GF30. There are two snap-fit arms inside (cantilever type), about 2 mm-thick walls. I’m not sure where to place the ejector pins without risking marks or deformation near those arms. Anyone here dealt with ejector placement on flexible features like this? Especially with glass-filled nylons that don’t forgive much?

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[Tom Barton]

Yeah, PA6 GF30 can pose challenges in that. It’s stiff, brittle around thin walls, and really doesn’t respond well to localized stress at ejection. I’ve had similar issues with snap-fit tabs. The main guide is to avoid placing ejectors too close to the cantilever root.

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[May Hall]

That makes sense. Would it help to reinforce the base of the arm somehow to take the pressure?

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[Tom Barton]

Up to a point. Even with gussets and larger fillets, concentrated ejection force near the arm can still cause pre-fracture or warping. Ideally, place ejectors on the opposite face, on a thicker wall, so the part pushes off more uniformly.

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[May Hall]

But the housing’s not symmetric, and most of the meat is on the same side as the arms. Thoughts?

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