EDM, or Electric Discharge Machining, is also sometimes referred to as metal disintegration. Many have heard of this method through the originator of the first EDM machines, Elox. The process works by using an active coolant ram style machine which utilizes an arc produced by a transformer. The electrode in the ram of the machine attaches to a solenoid. The solenoid vibrates the hot electrode causing it to make and break contact with the ground source; which, in this case, would be your broken bolt, tap, drill, or whatever.Coolant at 90 PSI is pumped through the electrode to the tip. The arc is drawn between the tip and the broken material. This melts a small amount of material which the pressurized coolant cools and flushes from the hole; this process does not heat the surrounding material. This process repeats at thousands of times per minute until the center of the broken material has been removed. After this core has been removed, Eric carefully peels away the remaining unwanted material without damage to the original part.
EDM is the best application for:
- Machined parts.
- Automotive parts off of a vehicle.
- Large bolt diameters: 1" and larger.
- Taps: 0-80 and up; Drills: .025 diameter and up.
- Hardened pins/bearing races.