Copper vs Graphite EDM

by Len Reiker
(St. Louis, MO)

Which is the best electrode material to use to EDM tool steel? I have been running EDM's for about 12 years now and I use both copper and graphite for my electrodes. Both materials seem to work well, but I tend to use them for specific purposes.


I use copper to make my electrodes when I have a tool to make that I can burn fast. For example, I use copper when I make a female electrode to burn the profile on the outside of a tool, or when I have a deep hole to burn. It seems to last longer and I can burn faster.

I tend to use graphite when I have to burn a fine detail on a tool, like a face detail on a punch or a gear profile. Graphite seems to hold the detail better but I have to burn it slower.

Do you have the same practices? Does anyone have a better way to EDM tool steel?

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May 23, 2012
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EDM copper/graphite
by: Wiilie Casper

We tend to use the same type of setup. We use 110 copper for fast burning electrode jobs and graphite for the fine detail type of work.

We buy copper plates, cut into squares and wire EDM the punch profile into them, then burn them using our sinker EDM.

We buy EDM graphite and precision machine or grind the reverse face detail of our punch onto them and then plunge EDM on to the top of our punch face. The graphite seems to work well in this situation.

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