Re: [CAD_CAM_EDM_DRO] Wire ECM

Hi Graham and All:
I have a few of these also. Only I call them white throne ideas
as that is usually where there are formed. One of them goes along
with your Wire ECM idea. I had thoughts of adapting a wire EDM to my
CNC mill for the XY movment but was going to have to add a traveling
wire to the system. Your ECM w/o the traveling wire could work great
on a vertical CNC mill. You could put the wire holder in the chuck
on the Z axies with a tank clamped on the table. Then go for it with
the chemicals and power. Let us know how yours turns out as I think
this would be great for thin metal stencals.
GOD'S BLESSINGS
Bill


This is a bit of a brain fart so appologies.

Firstly note the C, this is electroCHEMICAL machining I am refering to.

The basic concept is metal forming by the un-electroplating of the
workpiece. It is fast compared to EDM has less complex control and
can, like EDM, machine hard materials. It is however isotropic not
"closest point first" so the gap between electrode and workpiece must
me small to ensure a high current density and low side cutting. The
electrolyte can range from salt water to weird acids. Unlike EDM the
electrode is NOT eroded!

As some may know I am working on a micro wire EDM machine and I have
been playing with a RC supply based on Ben Flemming's book. I am
setting myself up to do some single axis wire EDM to assess the needs
of the supply and the cutting speed etc. It got me thinking that a
simple supply of that sort might also be used for ECM, and then I
started to wonder about wire-ECM.

I have never seen or heard of a wire ECM, I can think of many reasons
why. Even if you can insulate the rear 180 degrees of the electrode
and rotate it to follow the cutting vector it will cut sideways. If
the material thickness varies, the gap control becomes more complex,
it must be measured. So for precision, wire EDM wins hands down.

what about general profiling? Well water jet obviously or laser.
What about at home? Well there is plasma for steel and a CNC mill or
router for aluminium a cnc router.......

So here is my idea, build a simple wire ECM machine for doing basic
cutting jobs in sheet metal from steel a few mm thick to alumnium an
inch thick.

The concept, you need a tank in which the work can be positioned.
Unlike wire EDM the wire is not eroded, therefore it does not need to
be a moving wire system. If stainless wire is used there will be
little plating of the wire and it should be quite strong. Control is
via the current, we assume a sheet material so that the thickness
should remain the same roughly and current control should work, so you
do some experients in test pieces. You set up mach for constant
velocity and a slow feedate, the wire advances, if the current goes up
too much you pause mach until it drops, if the current gets too low
you tweak the feedrate (perhaps do that with the modbus stuff). If
the kerf is too big you increase the current.

Another important design feature is that the wire should be insulated
above and below the work. If the lower wire holder is of fixed height
then it can protrude through a insulating block. The upper wire could
have a block of insulating material that slides up and down it and
sits on the work piece.

so that's the idea, burr free wire style cutting of sheet metals at home.

Power supply BTW should be about 15v and whatever current you think
you need, for a thin wire not all that thick. I'll try and find out
what the cutting speed might be.

worth a play, it will all depend on that speed and cut quality!

Graham