I'm designing a watertight pushbutton. It has 2 pieces of machined stainless steel (303). One piece looks like a piston and the other is it's housing with a positive stop. For the seal, I have a neoprene washer with a beveled outside edge (to minimize friction). It is sort of like an o-ring setup, but the pointed edge makes it easier to depress and rebound. I'm using lithium grease as a lubricant and it's working well, but I'm concerned about how long I can expect it to keep lubricating the seal. A tiny bit of grease still tends to seep out of the front of the button after playing with it since yesterday morning (I'd estimate 300-400 cycles). I didn't put much in it to begin with, so I'm not sure if it's just excess or what. Has anyone had experience with a situation similar to this?
It's also doing something that is most likely not going to be acceptable. After letting the button sit for 30 minutes or so, the button takes a significantly higher breakaway force to depress it. Could changing over to a different lube help?
Thanks in advance.
