Re: [CAD_CAM_EDM_DRO] Re: Looking for EDM wire

Hi Dave:
What hole depths are you hoping to get?
The reason I ask is that the burn will become progressively more
difficult to sustain as you go deeper into the hole.
The reason is that it gets harder and harder to get the dielectric fluid
down the hole, and the crud out of the hole.
Tiny electrodes need tiny currents ...therefore tiny spark
gaps...thereby compounding the problem of maintaining the correct
flushing conditions to maintain the spark erosion process.
Take a look at the mechanics of a hole popper EDM to get an idea of
what's required.
Typically, they use a hollow tube electrode wherever possible, and they
force flush with high pressures. (a couple of hundred PSI as I recall)
They also support the tip of the trode with a ceramic bushing so the end
doesn't flop around like a garden hose.
They are amazing machines though...they'll drop a tiny trode through a
hardened steel block at rates almost as fast as a gundrill, and with
unbelievable depth to diameter ratios.
I recently had some custom sleeve pins wire cut for an injection
mold...1/8" OD with a 1/16" bore and 6" long.
The wire EDM guys hole popped starter holes with an 0.050" trode and it
took all of an hour or so to pop 4 pins.
(By contrast, my CNC sinker with a Rotobore and 60 PSI flushing with an
0.050" tube took an hour to get down an inch and a half, and I used up
an inch of trode to do it.)

But this process is critically dependent on all the systems working
together...and flushing is one of the most important of those.
Tubes are available down to 0.010" or so I believe...getting fluid down
such a tiny tube is probably not too easy.
If your depth is not much more than one diameter or so, and if you can
peck the electrode, you may well get away without elaborate flushing,
but if your plan calls for holes of any depth, forget it!!!
Cheers

Marcus