Graphite electrode Characteristic: Recent Episodes
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Characteristic and application of Graphite electrode,crucible,rod from famous manufacturers and suppliers
Graphite electrodes are mainly made of petroleum coke and needle coke, and coal tar is used as a binder. It is made by calcining, batching, kneading, pressing, roasting, graphitization, and machining. It is mainly used for electric arc steelmaking furnaces, mineral heat Electric furnaces, resistance furnaces, etc., graphite electrodes for steelmaking account for about 70% to 80% of the total amount of graphite electrodes.
Affected by environmental supervision, some graphite electrode manufacturers are i a state of discontinued production, leading to a reduction in the production of graphite electrodes.
With the structural reform of the supply side, the steel industry continues to pick up, driving the demand for graphite electrodes.
The graphite electrode has a long production cycle, at least 4 months, and it takes about half a year to stack up the stocking time. The supply is less than the demand, resulting in a continuous rise in the price of graphite electrodes in the short term.
It is very important to choose a graphite electrode manufacturer. When choosing a graphite electrode, pay attention to choosing some that are more cost-effective. Don't just choose based on the price, because this is not very wise in general. If it is said that it is not possible to achieve the final result in many places Understand, blind selection is not recommended.
The manufacturer who chooses the graphite electrode must be able to shop around. In the end, the best quality and products can be guaranteed. If you don’t understand the problem in this regard, you can simply ask the local buyers, so that you can get first-hand information, so that no special problems will arise no matter which product method or product Manufacturers, don't pay attention to just comparing prices! This is a very unwise way or search on google to see if their company is well known. You must know that if the quality of graphite electrodes is poor, it may not meet the production needs.
As the electrode material, electrical conduction and heat conduction are first required. In the electric discharge machining, the temperature of the gap between the electrode and the workpiece is 2000 to 3000 ° C due to partial discharge, and therefore the electrode material is required to withstand high temperatures. If the melting point of the electrode material is low, it cannot be quickly processed with a high current, the processing speed is low, and the processing cost is increased. In theory, tungsten or a tungsten alloy is the best electrode material. The tungsten electrode has the characteristics of high strength, high density and melting point of nearly 3400 ° C. The actual loss of the tungsten electrode is small in the electric discharge machining.
However, tungsten electrodes have two problems:
1, tungsten is difficult to process.
2, the price is expensive. In the 1960s, fine-structured graphite was used as the electrode material for rough machining of EDM machines. Among the electrode materials used in EDM machines in the 1960s, metal materials accounted for 80%, while graphite materials accounted for only 20%.
Compared with copper electrodes, ultrafine graphite electrodes have obvious advantages.
The first is to increase the speed, and the volume of metal etching per hour is called the processing speed. The processing speed of the ultrafine graphite electrode is 1.5-3 times faster than that of the copper electrode. Large area processing under high current conditions. However, due to the lower melting point of the copper electrode, the processing current is limited.
Moreover, the tolerance of the workpiece profile after machining is the machining accuracy, which is closely related to whether the electrode material is resistant to wear. In EDM, there are several kinds of losses in the electrode material; such as volume loss, end face loss, side loss and corner loss, among the four kinds of losses, the corner loss is the largest, and the corner loss determines the service life of the electrode. Since the final machining wheel is determined by the electrode loss at the corners and edges of the electrode, the life of the electrode is the longest if the weakest portion of the electrode is effective against loss.
The melting point of ultra-fine graphite rod is 2000 °C higher than that of copper. The strength of ultra-fine graphite rod is higher than that of copper. The angular loss during processing is small, which means that the service life of ultra-fine graphite is long and the processing cost is lower than copper. electrode.
Secondly, it can be processed with high precision. On the 13×13mm ultra-fine graphite rod, 2813 holes with a diameter of 0.02mm can be drilled. The hole is 0.05mm apart from the hole, and the copper is lower than the ultra-fine graphite. Processing is powerless.
Also, it is easy to process, ultra-fine graphite is made into an electrode, only 1/3-1/5 of the copper electrode.
Finally, the thermal expansion coefficient of ultrafine graphite is only 1/4 of that of copper. Therefore, the original design size of the die does not change during the processing due to the heating of the electrode, and the dimensional stability of the graphite electrode is good.
Graphite has high high temperature strength, low thermal expansion coefficient, good processability and good heat and electrical conductivity. Therefore, graphite electrodes are widely used in electric furnace, metallurgy, EDM and other fields. In the field of EDM, the development of new graphite electrode materials and their processing technology has expanded the application range of EDM and improved its performance.
Compared with the copper electrode, the graphite electrode has the advantages of small electrode consumption, fast processing speed, good machinability, high processing precision, small thermal deformation, light weight, easy surface treatment, high temperature resistance, high processing temperature, and electrode bonding.
Although graphite is a very easy to cut material, the graphite material used as the EDM electrode must have sufficient strength to be damaged during handling and EDM processing, while the electrode shape (thin wall, small rounded corner, sharp change) Etc. also imposes high requirements on the grain size and strength of the graphite electrode, which leads to the graphite workpiece being easily broken during the processing and the tool being easily worn. Therefore, how to prevent the workpiece from collapsing, improve the surface processing quality, and reduce the cost of machining tools has become an important issue in the processing of graphite electrodes.
In general, the electrode-consuming graphite electrode consumes 5 in the smelting process: electrode tip evaporation, electrode sidewall oxidation, electrode breakage, electrode residue loss, and electrode tip peeling. The loss of electrode breakage, surface peeling and rapid loss can be collectively referred to as abnormal consumption, which is different from the chemical reaction loss mainly caused by oxidation.
In combination with the consumption factors of the above graphite electrodes on the electric furnace, for high-quality graphite electrodes, under the conditions of careful operation, the abnormal consumption in the amount of graphite electrode consumption is not very large, accounting for about 1%-15% of the total consumption. Electrode breakage during electric steelmaking is a common failure. It is pointed out in the literature that in the practice of electric furnace production, as long as the performance of the electrode, the current load and the operating method of the electric furnace meet the requirements, the incidence of electrode breakage accidents is low, and the influence of continuous consumption on the total consumption of the electrodes is the most important.
However, for downstream customers, graphite electrodes only account for a very small part of their total cost. The quality and stability of graphite electrodes have a significant impact on their continuous production. In the steelmaking process, electrode breaks directly lead to electrode loss and increased consumption. In addition to increasing the cost of smelting, it is more important that production will be interrupted and production losses will be caused by the loss of production. Disposing the electrode to break the residue is the most difficult task in the operation, and the result must be excessive consumption, lengthening the smelting cycle, reducing the yield, and increasing the cost. Downtime and dead furnaces caused by graphite electrode quality problems will generate a large amount of indirect costs, so downstream customers are relatively more sensitive to electrode breakage problems.