Re: Wire ECM

--- In CAD_CAM_EDM_DRO@yahoogroups.com, jesse Brennan <jkbrennan@...>
wrote:

>
> I have an old copy of a 250 page monograph on ECM.
>
> Tool materials are called out as copper, brass, bronze , stainless
> steel, a copper - tungsten alloy for close gaping , and 12% Chromium
> steel. For deep hole production-- titanium. no graphite use is
> mentioned.
>
> Current densities are quit high-- about 1000 Amps per square inch.
> To remove heat flow velocities of the electrolyte may range
> from 50 to 100 feet per second.. In practice 100fps is more
> normal. pressures are quite high ( Maybe 500 psi) and the force
> between tool and work is about the same as in conventional machining.
>
> These indicate that a home built machine is probably impractical.
>
> I know people have done home electroetching for thin part production
> ( stencils etc) but this not to the same detail and extent as
> produced by true ECM.
>
> jesse
>
>

Any chance of a copy or is it paper only?

Considering I have made some holes with ECM myself using windscreen
washer pumps and the like I am not quite ready to throw the towel in
on the process. If we were to quote the vital statistics of any
commercial grade CNC machine we would think it impossible to homebuild.

One way to reduce pressure requirements is to retract on a more
regular basis, bad for industry but good for us. The parts produced
in the link I sent seemed to have been made on a machine based on very
regular retraction.

I almost forgot, I did actually try a form of wire-ECM last year, the
idea was to make a device for cutting hardened shafts in situ. I took
some strong wire and put a piece of fibreglass braid over it. I hung
the wire over the test shaft (a milling cutter) and applied a constant
flow of salt water and some electricity. The braid allows the fluid
to pass while preventing a short circuit. It did sort of work but the
process definately needed some refinement, I suspect the main problem
was the size of the gap being too large and the lack of real flushing.
It might have made sense to make the wire move between two reels like
a band saw.

Graham