How to distinguish between good and bad graphite?
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How to distinguish between good and bad graphite?
1 the flexural strength of the data
The flexural strength of the data is the direct expression of the strength of the data, and the internal structure of the data shows the degree of tightness. The high strength of the data, the discharge of the loss function is relatively good, high precision on the request of the electrode, as far as possible to select the better strength. For example: TTK-4 can be satisfied with the general electronic connector mold request, but some have special electronic connectors mold precision request, can choose equal size, but the strength is slightly higher data TTK-5 data.
Shore hardness of 2 data
In the unconscious of the graphite, graphite is generally considered to be a soft material. But the practice test data and the use of the situation, the hardness of graphite is higher than the metal. In the special graphite occupation, the general hardness inspection standard is the shore hardness measurement method, the test principle and the metal test principle is not the same. Because of the layered structure of graphite, it has a very superior cutting function in the cutting process, the cutting force is only about 1/3 of the copper material, and the surface is easy to be processed after machining.
But because of its high hardness, when cutting, the loss on the cutting tool will be slightly larger than the cutting tool. Together with this, the hardness of the material is excellent in the discharge loss control. In our EDM information system, on the use of more equal size data has two data available, a slightly higher hardness, a hardness slightly lower, with a variety of different satisfying customer's request. Such as: uniform particle size of 5 m data, there are ISO-63 and TTK-50; uniform particle size of 4 M data, there are TTK-4 and TTK-5; uniform particle diameter of 2 m of data, there are TTK-8 and TTK-9. Mainly taking into account the various types of customers on the discharge and mechanical processing of the focus.
3 data of uniform particle diameter
The uniform particle diameter of the data directly affects the state of the data discharge. The smaller the data, the more uniform the discharge of the data, the more stable the discharge, the better the quality of appearance.
About the appearance, precision casting, the request is not high casting mould, general introduced the use of coarse grain materials, such as ISEM-3; electronic mold of high precision, appearance request, recommending the use of uniform particle size of 4 m the following information, to ensure the machining accuracy of the mold, surface smoothness. The smaller the average particle size, the smaller the loss of the material, the greater the force between the ions. For example: general introduction in fine casting mold, die casting, ISEM-7 has been sufficient to meet the requirements of customers; but on the precision request is very high, recommend using TTK-50 or ISO-63 data, to ensure that the data loss is smaller, and then ensure the mold precision and surface roughness.
Together, the larger the particle, the faster the discharge rate, the smaller the loss of rough machining. Mainly the discharge process of the current intensity is not the same, resulting in the discharge of the energy of different sizes. But the discharge after the appearance of the particles also follow the change of the particle. Graphite material
4 data inherent resistivity
Based on the characteristics of the information we have calculated, if the data of uniform particles, the resistivity of the discharge rate will be smaller than the resistivity of the slow. On the equal and uniform particle size data, the resistivity of small data, its strength and hardness will be slightly lower than the resistivity of the data. That is, the speed of the discharge, the loss will be different. Therefore, it is very important to select the materials according to the need of practical application.
Because of the special nature of powder metallurgy, the parameters of each batch of data have a certain degree of shaking. But the same level of graphite materials, the discharge effect is very close to, because the difference between using effects of various parameters on the formation of very small. Graphite material
The selection of electrode materials is directly related to the role of discharge, to a large extent the choice of data is not appropriate, the resolution of the discharge rate, processing accuracy and the final surface roughness
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