In the 1960s, copper was widely used as an electrode material, accounting for about 90% of the total usage, while graphite accounted for only about 10%. In the 21st century, more and more users began to choose graphite as the electrode material.
In Europe, more than 90% of the electrode material is graphite. Why can graphite electrodes replace copper electrodes? What are the advantages of graphite electrodes?
1. The processing speed is fast. Generally, the processing speed of graphite is twice that of copper, and the processing speed of electric discharge is twice that of copper.
2. The material is not easy to deform. It has obvious advantages in the processing of thin rib electrodes; the softening point of copper is around 1000 ° C, which is easily deformed by heat; the sublimation temperature of graphite material is 3650 ° C; the thermal expansion coefficient is only 1/30 of copper.
3. Light weight, graphite density is only 1/5 of that of copper, the use of electric discharge method to process large electrodes can effectively reduce the load of the machine tool and is more suitable for the application of large molds.
4. The discharge consumption is small. Since the spark oil also contains C atoms, the high temperature causes the C atoms in the spark oil to decompose, forming a protective film on the surface of the graphite electrode to compensate for the loss of the graphite electrode.
5. No burrs. After processing copper electrodes, manual trimming is required to remove burrs, while graphite processing has no burrs, which saves a lot of costs and makes it easier to achieve automated production.
6. Graphite is easier to grind and polish, because the cutting resistance of graphite is only 1/5 of that of copper, so it is easier to grind and polish by hand.
7. The material cost is low and the price is stable. Due to the rise in copper prices in recent years, the price of isotropic graphite materials is lower than that of copper, and the price of general graphite products is also lower and more stable than that of the same amount of copper.
The anti-oxidation treatment process of graphite electrode includes material preparation, weighing, preparation of immersion solution, electrode immersion treatment and drying treatment. Compared with the untreated graphite electrode, the oxidized graphite electrode has the characteristics of smooth surface and good conductivity.
The mechanical strength is increased by 50-60%, the porosity is reduced by 10-15%, and the consumption of graphite electrodes can be reduced by 20-25%. The consumption of electrodes can be reduced by 20-25%.
The anti-oxidation treatment process of graphite electrode is completed through the following steps:
(1) Weighing of preparation materials: Weigh the graphite electrode to provide qualified materials to be processed;
(2) Preparation and heating of the immersion solution: the components of the immersion solution include industrial boric acid and industrial borax, mixed with water and mixed with water to form a liquid, and heated after preparation;
(3) Dip electrode treatment: Put the prepared graphite electrode into a vacuum tank and seal it, use a vacuum pump to evacuate, and inject the heated immersion liquid into the vacuum tank for electrode immersion. During the electrode immersion process, the concentration of the electrode immersion solution decreases. be supplemented as appropriate;
(4) Secondary weighing: after the electrode immersion treatment, open the vacuum tank, take out the immersed graphite electrode, drain the leaching solution, and the weight gain of the immersed electrode is more than 10%;
(5) Drying treatment: the immersed graphite electrode is dried so that the moisture content of the electrode is not higher than 0.5%;
(6) Three times of weighing: weigh the graphite electrode again after drying, so that the weight increase is more than 3% of the weight before immersion;
(7) Finished product processing: The above-mentioned treated graphite electrodes can be processed into standard shapes as required.