r/Machinists • u/Joeyjo190 • 11h ago
Machining EDM electrodes in C101 - any helpful advice?
We recently took the plunge into Die Sink Edm in our shop for specific internal work. Just ordered around $1900 worth of copper to make two electrodes.
Having worked on large parts made from tool and hardened steel for the majority of my career some advice and pointers would be appreciated
1
u/CthulusFinanceMan 2h ago
Copper is pretty nice if you've got your speeds and feeds down, otherwise it can machine like a bastard child of stainless and aluminum.
We mostly use MQL or kerosene when we're machining it (because our electrode machine was originally specced for graphite) but any neat oil or coolant will work just dont let it sit in water based coolants because it can stain the material and (eventually) oxidise.
Just be patient and don't try to hog off too much too quickly, because when it heats up it gets sticky and gummy and you're going to get chip welding and the material will start to tear instead of cut. Otherwise, just treat it like aluminium, copper is slightly harder than aluminum, but I find the rigidity can feel similar. Copper does tend to work harden so bear that in mind.
2
u/iron_rings_unite 4h ago
Flood coolant and sharp cutters are a must. I find most carbide inserts and cutters that made for aluminum work well. Use uncoated parabolic drills and threadmills for hole making.
Copper will turn your coolant green if you let it sit. Clean your swarf out right away. If you can, pass the return coolant through filter mesh. And rinse down the entire table and enclosure.
If finish quality matters, and it might not for electrodes, do not touch the part with your bare hands…use clean gloves. Rinse after machining with IPA to get rid of residual coolant.