EDM prototypes from 410 stainless. Harden the stacks or the parts. 1

[fish2win]

This is my first post on this forum. Thanks for reading. Any advice is appreciated.
I have to make a snap ring from type 410 stainless steel. My question is this... Should I build the stacks and have them hardened first and then wire them out or should I just have the parts hardened after. The OD of the rings is 1.004" +/-.002". My concern is that they will move during the heat treating process and possibly warp. My associates say the parts may move regardless of which way we proceed. For reference I've uploaded a print.
Thank you.
Jim

 

[CoryPad]

I think there are some important details unspecified, but I think I can understand your post enough to comment.

There is risk with either method. If you use wire EDM on a pre-hardened material, you can get a re-cast layer that is not hard, is cracked, or will initiate cracks upon loading. If you harden after machining, you may get distortion during quenching.

Are you familiar with how millions of these parts are made? It is by hardening after forming. However, a common process used is isothermal quenching in molten salt, which has much less distortion than traditional oil quenching.

 

[fish2win]

Thanks for the quick reply. I will discuss your recommendation with my heat treating vendor. Looks like I may have to make extra parts a sort out the best of the lot after they are hardened. Again, thank you.
Jim

 

[unclesyd]

Have you go to stay with EEDM?

We had case where the thickness didn't meet the design requirements which was resolved by taking a thicker shaft ring and using diamond lapping to get the required thickness. If my recall is working I believe the thickness was taken down 0,010"