The Machining Of The Graphite Electrode
(1) Processing form of graphite material
There are three main forms of processing of graphite electrodes: pressure vibration method, numerical control automatic forming method and mechanical processing method.
1) Pressurized vibration method: The pressure vibration method requires a special machine tool, and the electrode master mold has the opposite shape to the electrode.
The graphite material and the forming tool are placed opposite each other during processing, leaving a certain gap. A machining fluid mixed with water and abrasive is injected into it. The graphite and the forming tool are ultrasonically vibrated while passing through the working fluid. Under the action of abrasive impact, graphite is slightly stripped to the desired shape. The abrasive is SiC, B4C or diamond, and the thicker the abrasive, the faster the processing speed.
The machine tool works with sealed and water curtains. Suitable for EDM forming for mass production.
2) Numerical control automatic forming method: The numerical control automatic forming method requires a special graphite electrode forming machine, which adopts numerical control mode and has automatic tool changing device, which can accommodate multiple tools.
In order to improve the processing environment, the graphite electrode is surrounded by a water curtain to prevent the graphite dust from being scattered. Alternatively, the wet processing method can be used to prevent the tool from being worn and the graphite dust from scattering by the water-soluble cutting fluid. The machine tool has a high-performance filter device, which can separate the cutting fluid and graphite chips, and can ensure continuous processing for a long time. It is an ideal special equipment for graphite electrode processing and is suitable for electrode processing of molds.
However, its price is relatively high, and it is not common in domestic applications.
3) Machining method: The mechanical processing method is the main method adopted by domestic general mold production units.
Graphite materials can be processed by turning, milling, drilling and grinding. In addition, graphite materials are prone to fly ash during machining, which adversely affects processing equipment and operators.
(2) Processing procedures for graphite materials
1) Graphite oil immersion. Before the mechanical processing, the graphite material should be immersed in the oil for several tens of hours to allow the oil to penetrate into the graphite material, so that the ash powder does not fly during machining and a smoother surface can be obtained.
2) Paint scribe line. After roughing the surface of the electrode, a thin layer of white lacquer is applied to the surface of the scribe line and then scribed, so that the line is clear and easy to machine.
3) Perform machining.