Sinker EDM question about making a fourth electrode.

[PegroProX440]

I have been making electrodes for years but in the past two months I have taken over the Sinker EDM as well. So I'm pretty new. We have a Mitsubishi EA28V.

Usually we make three electrodes per feature being burned. Somewhere in the range of 18 to 24 VDI for the finish. If I am looking to get a more crisp corner on a tight feature we sometimes make a 4th electrode to get that last little bit.

My question is, when I am using 4 electrodes, is it best practice to tell the EDM that I am using 4, and let it figure out the power settings for each one. Or should I program it as 3 and use that last electrode at the identical power settings as #3. So its just a redundant trode to get any remaining stock.

 

[PegroProX440]

Also, any tips to get better finish burning 303ss....

 

[William Ward]

No tips on burning 303SS.
However I use 4 electrodes all the time on our Mits EA12E. The control seems to out put the same settings for electrode 3 and 4. If you do a simple 4 trode program in ESPER and after you get back to the program screen look at the button menu on the right side of the screen. Push "Next" and on the next menu push "M Compile" and then press whatever passes for OK on the popup. That will break out the settings for each electrode. This is where you can most easily control size by adjusting your overburn and depth. Also if you are trying to sneak up on a .0001 or .0002 tolerance always run the program again without changing anything.

So yes, tell it you are using 4 trodes.

 

[007Rob]

Curious what kind of spark gap are you guys running for your 3rd and 4th electrodes?

We're running an AgieCharmilles machine so can't really compare exact settings but I've had situations where I think it would be helpful to have a final electrode with a very small spark gap lets say ~.001" or so to really get into those fine details.

I just make the trodes but our edm operator can't seem to generate a program that the machine will accept under .0016" or so. We can see the final orbits running at .0008" overburn so I would think it should be possible but not sure if I'm missing something or we just need more training on the machine.

 

[William Ward]

At least on the Mits machine .0015" is the smallest gap it will take. When the machine breaks down the burn into decreasing overburn as the burn progresses you will see smaller gaps but not up front when you are making the program.
On my fine detail stuff I use .0015 over burn and cheat a little by rounding down on my burn area calculation. Although the smallest burn area it will take is .01 sq. in. so the rounding down won't always work. I have burns with .0001 sq. in. face area.

 

[White Lightning]

Curious what kind of spark gap are you guys running for your 3rd and 4th electrodes?

We're running an AgieCharmilles machine so can't really compare exact settings but I've had situations where I think it would be helpful to have a final electrode with a very small spark gap lets say ~.001" or so to really get into those fine details.

I just make the trodes but our edm operator can't seem to generate a program that the machine will accept under .0016" or so. We can see the final orbits running at .0008" overburn so I would think it should be possible but not sure if I'm missing something or we just need more training on the machine.

In my experience something to think about when throwing a smaller spark gap to crisp up corners.

When you look at wear % a .0015-.003 spark gap has really high wear rate on the last few power lines. Since the first down line does 90% of the work adding a trode with small s.g. at the end has minimal effect on the actually radius left. The trode simply wears .

Try roughing with 1 electrode with the max spark the trode will allow and follow with 3 or more trodes with minimal s.g. this will get the best results in achieving small corner radius.

Sent from my SM-G960U using Tapatalk

 

[Zero Tolerance]

This is a good question because we do the same thing, we have done it this way using 4 electrodes but only programming 3 and using that last trode at the same power settings as number 3.

Someone who can give you a really good explanation of these settings is a guy named Jim Weirdo from MC Machinery, you can call him and ask what he thinks is best too.

We have also programmed the 4th electrode and got similar results but it depends on how many locations you're looking to burn. I would suggest trying both ways and see what works best for you.

We have a Mits EA12V & a Gantry Eagle 800 we've done this on both.