Amongst the many types of plastic mold machining, electrical discharge machining is one of the most commonly used. 

Its main advantages include high precision, precision shape and depth, and a superior surface finish. 

Machined surface is more rough.

The electric current spalls metal into the machining liquid, and the metal cools to form metal "dust" that is carried away by the liquid.

The main difference between EDM (Electrical Discharge Machining) and ECM (Electrochemical Machining) machines is in their working principles:

EDM (Electrical Discharge Machining): EDM uses electrical discharges to remove material from a workpiece. It relies on sparks or discharges of electrical energy to erode the material, making it suitable for hard metals and complex shapes.

ECM (Electrochemical Machining): ECM employs a chemical process to remove material. It uses an electrolyte solution and an electrically conductive tool to dissolve or erode the workpiece material, making it effective for conducting materials like alloys and difficult-to-machine metals.

In summary, EDM uses electrical discharges, while ECM uses an electrochemical process to shape and machine materials.

EDM electrodes consist of highly conductive and/or arc erosion-resistant materials such as graphite or copper. EDM is an acronym for electrical discharge machining, a process that uses a controlled electrical spark to erode metal.