soderberg electrode paste
Die electrical discharge machining, which is better, copper soderberg electrode paste or soderberg electrode paste
Die electrical discharge machining, which is better copper soderberg electrode paste or soderberg electrode paste. Copper is widely used as a material of soderberg electrode paste in EDM in mold factories. Many people think that graphite material will only be considered as an alternative consideration when making large-scale soderberg electrode paste and the mold processing requirements are not high or rough processing.
Nowadays, in Europe of manufacturing technology, the soderberg electrode paste material of mold companies uses graphite. However, in China, most mold companies still choose copper as the main soderberg electrode paste material. According to the characteristics of graphite materials, the advantages and disadvantages of EDM are analyzed as follows.
EDM characteristics of graphite materials
(1) Electric discharge machining speed Graphite is a non-metallic material with a high melting point and can withstand larger current setting conditions. When the discharge area and the size of the soderberg electrode paste are enlarged, the superiority of the rough machining of the graphite material is more obvious. The thermal conductivity of graphite is 1/3 of that of copper, and it can be used to remove metal materials during the discharge process. Therefore, its processing efficiency is higher than that of copper soderberg electrode paste in medium and fine processing. According to the processing experience, under the correct conditions of use, the electrical discharge processing speed of the soderberg electrode paste is 1.5~2 times faster than that of the copper soderberg electrode paste as a whole.
(2) Soderberg electrode paste loss Soderberg electrode paste has the characteristics of being able to withstand high current conditions. In addition, under the appropriate roughing conditions, the erosion and working fluid generated during the processing of carbon-containing steel workpieces The carbon particles produced at high temperature will adhere to the surface of the soderberg electrode paste to form a protective layer under the effect of the polarity effect. , Even “zero loss”. The main loss of soderberg electrode paste in EDM comes from rough machining. Although the loss rate of finishing setting conditions is high, the amount of machining erosion is small because the reserved machining allowance of parts is small, and the overall loss is also less. In general, the loss of soderberg electrode paste in rough machining of high current is less than that of copper soderberg electrode paste, and the loss in finishing may be slightly greater than that of copper soderberg electrode paste. The loss of soderberg electrode paste of the two is equivalent.
(3) Surface quality The particle diameter of graphite material directly affects the surface roughness of EDM, the smaller the diameter, the lower the surface roughness value can be obtained. A few years ago, graphite materials with a particle diameter of φ5 μm were used, and the surface of EDM can only reach VDI18 (Ra0.8 μm). Nowadays, the particle diameter of graphite materials can reach within φ3 μm, and the surface of EDM can stably reach VDI12. (Ra0.4 μm) or a finer grade. The resistivity of copper material is low, and the structure is dense. EDM is easy to obtain a stable processing state, and it can be processed stably under difficult conditions. The surface roughness can be less than Ra0.1 μm, and it can be mirrored EDM. . It can be seen that if the electrical discharge machining pursues a fine surface, it is more appropriate to use copper materials for the soderberg electrode paste, which is the main advantage of the copper soderberg electrode paste over the soderberg electrode paste. However, under the condition of high current setting, the surface of the copper soderberg electrode paste is prone to become rough and even cracks, while graphite materials do not have this problem. The surface roughness requirement is VDI26 (Ra2.0 μm) For the left and right cavity processing, a soderberg electrode paste can be used to complete the machining process from coarse to fine, achieving a uniform texture effect. In addition, due to the difference in the structure of graphite and copper, the corrosion points of the surface discharge of the soderberg electrode paste are more regular than that of the copper soderberg electrode paste. Therefore, when processing the same surface roughness of VDI20 and above, the surface granularity of the workpiece processed by the soderberg electrode paste is More clearly, this texture effect is better than the discharge surface effect of copper soderberg electrode paste.
(4) Machining accuracy The thermal expansion coefficient of graphite material is small, and the thermal expansion coefficient of copper material is 4 times that of graphite material. Therefore, compared with copper soderberg electrode paste in electrical discharge machining, the soderberg electrode paste is less prone to deformation, and more stable and reliable processing accuracy can be obtained. . Especially when processing deep and narrow ribs, the local high temperature will easily cause the copper soderberg electrode paste to bend and deform, but the soderberg electrode paste will not be like this; for the copper soderberg electrode paste with a large depth-to-diameter ratio, compensation is required when processing settings A certain thermal expansion value is used to correct the size, and soderberg electrode paste is not required.
(5) Weight of soderberg electrode paste Graphite material has a lower density than copper, and the weight of soderberg electrode paste of the same volume is only 1/5 of that of copper soderberg electrode paste. It can be seen that the larger soderberg electrode paste uses graphite material to reduce the load on the spindle of the EDM machine tool. The soderberg electrode paste will not cause problems such as inconvenience in clamping and yaw displacement during processing due to its heavy weight. It makes sense to use soderberg electrode paste in mold processing.
(6) Difficulty in making soderberg electrode paste The machining performance of graphite material is good, and the cutting resistance is only 1/4 of that of copper. Under the correct processing conditions, the efficiency of milling soderberg electrode paste is 2 to 3 times that of copper soderberg electrode paste. . The soderberg electrode paste is easy to clean the corners, and the workpiece that is usually completed by multiple soderberg electrode pastes can be designed into a whole soderberg electrode paste for processing. The unique particle structure of the graphite material makes the soderberg electrode paste not produce burrs after milling, and it directly meets the requirements for complex shapes that are inconvenient to remove the burrs, eliminating the need for manual polishing of the soderberg electrode paste and avoiding polishing The resulting shape changes, size errors, etc. It should be noted that because graphite is a dust accumulation, a large amount of dust will be generated when milling graphite, so the milling machine must have a sealing and dust suction device. If you need to use wire EDM to process soderberg electrode paste, its processing performance is not as good as that of copper materials.
(7) The soderberg electrode paste has good adhesion between the installation and the use of graphite materials. Conductive glue can be used to bond graphite to the fixture for milling soderberg electrode paste and electrical discharge machining, which can eliminate the need to machine screw holes on the soderberg electrode paste material. The process saves working time. Graphite materials are relatively brittle, especially the small, narrow and long soderberg electrode paste, which is easy to break when subjected to external force during use, but it can be immediately known that the soderberg electrode paste has been damaged. If it is a copper soderberg electrode paste, it will only bend and not break. This situation is very dangerous and difficult to find during use, and it is easy to cause the workpiece to be scrapped. To sum up, in the eight EDM characteristics of soderberg electrode paste, its advantages are obvious: the efficiency of milling soderberg electrode paste and electric discharge machining is significantly better than that of copper soderberg electrode paste, and the production efficiency is high; large soderberg electrode paste is very suitable ; Good dimensional stability, thin slices of soderberg electrode paste are not prone to deformation; disadvantages of graphite materials: milling of soderberg electrode paste requires a special graphite processing machine which is not suitable for fine surface discharge machining below VDI12 (Ra0.4 μm); The superiority of soderberg electrode paste material will gradually be recognized and accepted by the domestic mold manufacturing industry. The correct selection of soderberg electrode paste material and the improvement of related process links will bring cost-effectiveness to mold manufacturing enterprises.