Hi durableoreo:
There are some very good books about how to RUN an EDM and how to BUY an EDM; the EDM Handbook by Bud Guitrau springs to mind.
There is much much less information about how to design the circuitry; this is held like gold by the EDM manufacturers to the point where even schematics of individual machines are very rare.
The basic challenge as I understand it is to create a current and voltage spike super quickly such that the waveform is almost square rather than sinusoidal, that all pulses be equal, that they occur at moderate to highish frequency and that they be responsive to external inputs through a feedback loop that starts with sending gap voltage information to the spark generator side of the control to say when to do it's magic
.
The desired effect is to create and then decay plasma channels in the dielectric fluid between electrode and workpiece such that electrons can flow and do useful work as they transit the gap via the plasma channel.
Over the years, successively more modern devices have been employed to achieve this goal with more precision and consistency while the gap sensing circuitry that dictates the electrode position relative to the workpiece position and therefore the discharge voltage trigger has also improved in responsiveness but also in the range of parameters it can sense (other than just gap voltage).
This in turn has led to improved circuitry to respond to these additional input conditions, so the ram (and electrode) no longer responds only to gap voltage but to "other things" as well.
As you can expect, this is all super top secret proprietary information that the EDM makers jealously guard and try to reverse engineer from each other.
So finding publications that reveal the current state of the art are going to be challenging to uncover.
Cheers
Marcus
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