Cutting Principle of Sodick EDM

1. Electrical discharge principle

  Sodick EDM adopts the principle of electric spark discharge machining. In processing, the electrode wire (generally copper wire and other conductive materials) and the workpiece to be processed are connected to the two poles of the pulse power supply. When the distance between the electrode wire and the workpiece is small to a certain extent (generally a few microns to tens of microns), the electric field strength between the poles will reach a very high value, so that the working fluid (usually deionised water or EDM special working fluid) medium is penetrated, the formation of discharge channels.

   The electrons in the discharge channel run to the positive pole at high speed, and the positive ions run to the negative pole, and the electric energy is instantly transformed into heat energy, and the temperature can be as high as 10000 - 12000℃, which makes the electrode wire and the local metal materials on the surface of the workpiece melt or even vaporise rapidly.

2. Material removal process

   Due to the high temperature generated by the discharge, the metal is melted and vaporised, and under the action of the explosive force of the discharge, the melted and vaporised metal is thrown away from the electrode wire and the surface of the workpiece, forming a small discharge crater.

   As the pulse power supply continuously sends out pulse signals, the discharge between the electrode wire and the workpiece is continuously carried out, and countless discharge craters overlap each other, so that the material of the workpiece is finally removed according to the predetermined shape and the cutting process is realised.

3. Role of electrode wire movement

   The electrode wire of a Sodick EDM moves slowly (the origin of the name ‘EDM’), which is different from that of a Rapid Walking Wire. The slow movement of the electrode wire plays an important role in that it constantly updates the discharge position of the electrode wire and prevents the electrode wire from being repeatedly discharged in the same position, which would lead to excessive losses.

   The new electrode wire continuously enters the discharge area, which can maintain a stable discharge state, and is conducive to improving processing accuracy and surface quality. At the same time, the movement of the electrode wire can also bring the metal chips generated by the discharge out of the discharge area, preventing the metal chips from accumulating in the discharge gap and affecting the subsequent discharge machining.

4. Function of working fluid

   The working fluid plays the roles of cooling, chip removal and insulation in the process of Sodick EDM cutting. In terms of cooling, it can take away a large amount of heat generated by the discharge, preventing the electrode wire and workpiece from being deformed or damaged due to overheating.

   Chip removal, the flow of the working fluid can discharge the metal chips generated by the scouring away, so that the discharge gap to keep clean, in favour of the discharge continues. Insulation role is to ensure that the discharge occurs only in the narrow gap between the electrode wire and the workpiece, and will not generate discharge in other unwanted places.