Processing method of graphite electrode
There are three main processing methods for graphite electrode: pressure vibration method, numerical control automatic forming method and mechanical processing method.
(1) Pressurized vibration method: the pressurized vibration method requires special machine tools, and the shape of the electrode mother mold is opposite to that of the electrode. Graphite materials and forming tools are placed relatively during processing, leaving a certain gap. The processing fluid mixed by water and abrasive is injected into the middle. While passing through the processing fluid, the graphite and the forming tool are ultrasonically vibrated. Under the action of abrasive impact force, graphite is peeled off to the desired shape. The abrasive is SiC, B4C or diamond. The coarser the abrasive, the faster the machining speed. When the machine tool is working, it adopts sealed type and water curtain type for processing. It is suitable for EDM in mass production.
(2) Numerical control automatic forming method: the numerical control automatic forming method requires a special graphite electrode forming machine. It adopts the numerical control method and has an automatic tool exchange 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 dispersing everywhere. In addition, the wet machining method can be used to prevent the tool from being worn and the graphite dust from flying away by the water-soluble cutting fluid. The machine tool is equipped with a high-performance filtering device, which can separate the cutting fluid from the graphite chip and ensure long-time continuous processing. It is an ideal special equipment for graphite electrode processing and is suitable for die electrode processing. However, its price is high and its application in China is not widespread.
(3) Machining method: machining method is the main method adopted by domestic general graphite electrode production units.
Graphite electrode can be machined by turning, milling, drilling and grinding. In addition, the graphite electrode is prone to fly ash during machining, which brings adverse effects to the processing equipment and operators.
（2） Processing procedure of graphite electrode
1) Graphite impregnated with oil. Graphite materials should be immersed in engine oil for tens of hours before machining to make the oil penetrate into the graphite materials, so that the ash powder will not fly during machining and a smooth surface can be obtained.
2) Paint scribe. After rough machining of the external surface of the electrode, a thin layer of white paint shall be sprayed on the marking surface for marking, so that the lines are clear and convenient for machining.
3) Perform machining.
