Perseo-Erie EDM Drill...aluminum trouble

Hi. Im new to the world of EDM wire machines and EDM drills. The other day I drilled a hole in a piece of 6061 aluminum that was 5 inches tall. When I tried to wire out my profile I kept getting a short circuit error after it cut approx .5 inch. I tried starting my cut at different spots and it kept doing the same thing. After getting aggravated, I just decided to come into the part from the outside and had no problems. Does the EDM drill actually change the properties of the aluminum? Is that a reason why I might have issues like that? Thanks!

Never heard of anything like that. I can't imagine that the properties of the aluminum has changed 1/2 inch away from the hole made by the hole popper. We've done this plenty of times with no problems. Could there have been something non conductive in the material? Can you cut through that same section coming from the outside of the part? That's a strange one.

Yes i used the same part and left it fixtured the same way and cut it coming from the outside and had zero issues. It cut fine. It doesnt make any sense to me. I asked a few people that have experience and they said theyve had the same problem with EDM drilling tall pieces but dont have any idea what the answer is. I can do one inch tall pieces without a problem but when i move up to 5 inch i have issues. If it helps at all, im using copper rod for aluminum. The holes drill without any issues on the taller parts. Its just when I try to wire them is when I have issues. Thanks for your help

Jordan

It might take a metallurgist or someone more versed in chemistry than I, but EDM drilling AL produces a chip ( burnt AL ) that is like a ceramic.
Hard, but most importantly, non conductive. Sort of like a hardcoated AL.
It is not an issue with shallow holes as the flushing will evacuate the molten material before it can re-solidify on the side of the hole ( or for that matter back on the drill tube)
On deeper parts however the small particles will coat the hole before they can be washed away, thereby creating a non-conductive layer which is an absolute PITA to cut through.

Now why this happened after you've got .5" from the hole ..... I have not a single idea. You should not even be able to cut out of the hole.

BTW similar issues arise with EDM drilling TI as well, tough you most likely wouldn't be able to finish the drilling op as the trode will simply bind up permanently before you
get through it.

I have heard of this issue with the outter layer of the hole. I forgot to mention that I drilled it on the EDM at like .040" diameter and then went back through it with a 1/16 drill bit on the drill press to try to clean it up.