I am interested in using a Wire EDM process to cut some silicon steel. As defined by Wikipedia - “Electrical discharge machining (EDM), also known as spark machining, is a manufacturing process whereby a desired shape is obtained by using electrical discharges (sparks).Material is removed from the workpiece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage.”

Material suitable for EDM must be electrically conductive of the process to work. The steel I want to cut is laminated in a dielectric coating however. I contacted a few Wire EDM cutting companies and was told by some that it was not possible to Wire EDM cut a dielectrically coated material, and told by others - “maybe, it depends”.

What factors would this depend on? I am thinking that if the voltage used in the EDM process is above the dielectric breakdown point of the coating, then the process would work - is this a correct way to think about it? For example, this website (http://www.engineersedge.com/edm.shtml) states the peak voltage used ranges from 40 to 400V. This website (http://www.industrialcoatingservicesblog.com/coatings-dielectric-strength) lists the dielectric strength of some coatings as ranging from 800 volts/mil to 6000 volts/mil.

If the Wire EDM uses 400V, but the coating on the material has a dielectric strength of 800 volts/mil, is it a safe bet to say the coating is too strong an insulator, and that the EDM process will not work?


If you know what the coating is, maybe you could remove it in the area you want to machine and recoat it once done. I would not rely on the EDM to break down the insulation as they /generally/ operate at about 50v in my experience. If they have a good starting point they can sometimes edge there way into the insulation area, but the factors involved at too many to even try to guess.

If the part your working on isn't too hard or maybe try not conventional machining methods? I wish I could be more help.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.