Occasionally you need to know how 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 process and designers find alternate ways to create components.
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.
These guidelines are just that: guidelines. Back in the days of Eltee-Pulsitron and other manual machines it was actually easier to EDM carbide. But that is a different story.
Basic guidelines to EDM carbide in a sinker EDM
- 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.
Here is a 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.
All in all, EDMing carbide is certainly doable and companies manage it every single day. The trouble is that it takes a lot of experimentation, most of the time.
You might be lucky and own an EDM sinker that has excellent customer support and the circuitry to manage the job. If not, try the above mentioned parameters and do some testing.