How To EDM Carbide In A Sinker EDM
Occasionally the need arises to EDM carbide in a sinker EDM machine, though not as often as in the
past. This is probably due to the fact that the WEDM is much better at this.
Nevertheless, when you have to burn carbide right now, you need to know how to do it, and it is not
so easy to find out what needs to be done. With some patience and a little experimentation, you will discover
that it is not so hard, but it is slow.
You should try to get some information from your EDM machine technical support, but most likely
they won't know, or will be too slow in responding. So, here is how you can EDM carbide in a sinker EDM.
How to EDM carbide
Use tungsten carbide for you electrode. You will most likely need to WEDM this, or you can
machine it, but it is not so machinable.
Use negative polarity to the electrode, which is reverse from normal.
Use low on and off times, which is high frequency.
You need a lot of patience as well, burning carbide is much slower than burning steel.
Expect a lot of wear—30%-50%, and longer cycle times than steel.
Ask your EDM machine supplier, but don't get too excited if you never find out from them!
For some reason, technical support can be rather sketchy at times. If you do have a good working
relationship, you can give them a call and ask them for some settings.
Each machine is a bit different, but the concept is the same. Play around with the settings, keep
track of what you use and monitor the results. Then, write it down and put it in your notebook for future
Here are some great resources
for electrical discharge machining
This is an authoritative DVD published by the Society of Manufacturing Engineers. It
is a comprehensive DVD that covers every aspect of EDM.
This DVD is and excellent training tool for new EDM people and "the rest of the company", who may
or may not understand this mysterious machining operation.