Electrical Discharge Machining is a machining technique that uses high powered electrical current to melt pieces of metal to form a desired design. It is used when the material that you are trying to work with is hard to machine by other methods. Hard alloys or metals such as tungsten, titanium, hastelloy, or kovar are commonly machined by electrical discharge though softer metals are sometimes used as well.
This type of machining uses sparks electrical sparks inside a dielectric fluid (non-conductive) to cut away pieces of metal. Normally this fluid is just distilled water but other fluids can be used if heat becomes an issue. It is also considered an unconventional way of doing machining and requires special training in order to be able to machine by EDM.
At first machining was done at 60 parks a second but today’s machines can do upwards of 10000 sparks a second. Engineers use magnetic fields to “force” the electrical spark into the direction they want by placing a magnet point under the material when you want to spark to go. This technique allows for quick machining while providing extremely accurate angles. This advantage allows for the creation of complex shapes that would be hard if not impossible to make by normal machining processes.
You will find electrical discharge machining in the mold making tool and die, prototype, and production parts industries. It is used heavily in aerospace and automobile industries as they deal with hard metals and require precise machining.
There are some disadvantages to EDM. In comparison to standard machining, EDM is slower in the removal or material process. Certain fluid used can become flammable and explode if the temperature is not carefully monitored. You can also expect your power bill to be much higher when using electrical discharge machining.
Overall if you go is to become a prototype machinist or just want to be able to make more complex parts you should look into getting training in electrical discharge machining along side your standard CNC training. Most assocaite degrees program go over EDM but few have hands on experience with the process. Make sure to check with your schools program director if EDM sounds fun for you.