1. Meaning
EDM is a method of processing using electricity and heat energy that was studied in the 1940s and gradually applied to production. EDM refers to the method of processing the workpiece through the electric erosion effect of the pulse discharge between the tool electrode and the workpiece electrode in a certain medium.
The difference between EDM and general cutting is that the tool and the workpiece are not in contact during the machining process, but rely on the continuous pulsed spark discharge between the tool and the workpiece, and use the local and instantaneous high temperature during the discharge to gradually corrode the metal material. Remove it.
2. Working principle
The principle of EDM is based on the electro-corrosion phenomenon during the pulsed spark discharge between the tool and the workpiece (positive and negative electrodes) to remove excess metal to achieve the predetermined processing requirements for the size, shape and surface quality of the workpiece.
The workpiece and tool electrodes are respectively connected to two electrodes with different polarities of the pulse power supply. Tool electrodes are usually made of electro-corrosion-resistant materials with good conductivity, high melting point and easy processing, such as copper, graphite, copper-tungsten alloy and molybdenum. During the machining process, the tool electrode also has loss, but it is less than the erosion amount of the workpiece metal, and even close to no loss. As the discharge medium, the working fluid also plays the role of cooling and chip removal during the machining process. Commonly used working fluids are media with low viscosity, high flash point and stable performance, such as kerosene, deionized water and emulsion.
When the pulse voltage is applied between the two electrodes, when a proper gap is maintained between the workpiece and the electrodes, the working fluid medium between the workpiece and the tool electrodes will be broken down to form a discharge channel. The instantaneous high temperature is generated in the discharge channel, which melts or even vaporizes the surface material of the workpiece, and also vaporizes the working fluid medium. After the pulse discharge ends, after a period of time, the working fluid is restored to insulation. The pulse voltage is repeatedly applied to the workpiece and the tool electrode, and the above process is repeated continuously, and the workpiece material is gradually etched away.
3. Advantages
EDM can process any conductive material, and is very suitable for processing low-rigidity workpieces, micro-machining and complex surface workpieces. Moreover, under the same surface roughness, the surface lubricity and wear resistance are better than machining, especially suitable for mold manufacturing.
4. Precautions
Pulse power supply must be used during processing, and spark discharge must be carried out in an insulating liquid medium. Of course, a certain discharge gap should always be maintained between the tool electrode and the workpiece surface to be processed. If the gap is too large or too small, it will affect the normal spark discharge machining.
Our company can provide various electrode products for EDM tools such as Tungsten Copper Rotary Electrode, Tungsten Copper Electrode Plate and Molybdenum Copper Electrode. If necessary, please contact us by email.
