Wire EDM and nitriding

I know some of you guys have a lot of experience when it comes to manufacturing gears and splines. I am looking to get a little help/input on manufacturing an internal involute spline.

To produce the internal spline we plan to use a wire EDM as we do not have the proper equipment to broach it. My fear with using a wire EDM is the re-cast layer that it produces. The adapter is going to be made from nitralloy and the teeth will be nitrided. So I am concerned that the re-cast layer may produce a brittle layer that when nitrided becomes even more brittle. Is it possible to remove this re-cast layer through hand lapping with a male plug?

I was hoping someone with experience could shed some more light on the issue and possible ways of getting around it.


We have a lot of experience in cutting dies using wire EDM. At first we had a lot of cracked dies - using A2 tool-steel hardened to 59-61RC - especially in sharp corners due to recast. The solution was to give the die a double minimum draw after wire EDM. Find out what the minimum draw is on the material you are cutting and hardening. If you are cutting low carbon steel - no problem.

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