Burning coolant hole into a carbide cutting tool to join existing hole. Arching and deformation

[bigj4]

I have a problem joining coolant holes in carbide using a copper electrode around 1mm in diameter. As the hole is being drilled in the perimeter of the tool the arch cuts the hole while feeding in but also arches around the electrode and damaged the cutting edge. Grounding is good, coolant is clean but he problem just appeared out of no ware.

 

[capnhook]

Please clean off the scale around your hole, and give us a look at that.

If the grounding is good and your coolant is clean, check for adequate flush.

Otherwise, if you have made this operation successfully before, I would suspect a flakey power control.


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