Niobium (columbium) electrode suggestions

[claya]

We are quoting a Niobium sinker job. In the past, we have used graphite (Poco-3) electrodes but wear was excessive. Copper Tungsten worked ok, but was VERY slow. Suggestions? We have an Eltee Pulsitron sinker, so can use capacitive discharge which works well for tungsten-carbide. I am not sure CD helps with Niobium.

Suggestions on electrode choice, burn settings etc..?

claya

 

[ggsma]

What settings are you using now? Electrode negative or positive?
First choice would be copper graphite,Poco C3.2nd choice would be Poco 3. Try titanium settings for your sinker,
definitely would be negative electrode polarity. Its going to take at least 3 electrodes,probably more, to rough and finish the cavity. With copper tungsten, use copper tungsten to carbide settings. Again, electrode negative, should burn faster but have more electrode wear.

 

[claya]

What settings are you using now? Electrode negative or positive?
First choice would be copper graphite,Poco C3.2nd choice would be Poco 3. Try titanium settings for your sinker,
definitely would be negative electrode polarity. Its going to take at least 3 electrodes,probably more, to rough and finish the cavity. With copper tungsten, use copper tungsten to carbide settings. Again, electrode negative, should burn faster but have more electrode wear.

We are only quoting a new job. Another shop suggested copper electrodes. Thoughts?
We do not have any setting for titanium in the manual. Only aluminum, steel & Carbide. Which of these 3 are closest to Titanium settings?

 

[ggsma]

Don't know much about copper electrodes, I only use them to burn holes and counterbores,nothing special. Here's a link to the Poco
Tech manual, you can check the charts and compare to your settings or modify the settings.
Poco: EDM Technical Manual