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In the EDM machining process, to understand the various dimensions of the cavity effect of changes in heat, will help customers to understand the EDM process on the impact the integrity of the mold surface. To protect the integrity of the surface cavity machining EDM one of the most critical issues. Cavity surface finish of the EDM machining process depends on the integrity of the cavity effect of the changes in levels of heat, including the charge electrode and the workpiece transfer between the control situation. In the EDM process, the current imposed on the workpiece to the workpiece metal to be melted and vaporized to form in the cavity layer thermal changes. In order to understand the integrity of EDM process on the mold surface impact, we must first understand the various dimensions of the cavity effect of changes in heat. EDM machining of the charge not only affect the surface of metal parts, and all levels below the surface are affected. Change the situation at all levels of the heat Affected by the EDM processing means at all levels change after metal heating area. Figure 1 shows the changes in metal after heating region, where heat from the impact of material composed of two layers: Recasting layer or white layer and heat affected zone. Figure 1, heat-affected sub-level and secondary sedimentary White layer is heated to the melting point has been the state of metal layers, but not enough to be excluded from melting into the cracks, to be washed away by the extent of the liquid medium. Indeed, EDM processing technology has changed the microstructure of the metal layer structure and characteristics of the liquid medium because of erosion in the process, would this be the rapid cooling of molten metal layer, and then solidified in the mold cavity on to form a new metal layer. This layer of metal, including some superior performance of particles being washed from the cracks in the liquid medium before solidification began, and again deposited on the mold surface. White layer and the infiltration of carbon closely together to make a change in metallurgical structure, performance, and the matrix material completely different. In EDM processing, when the electrode after decomposition of hydrocarbons and liquid medium, it will produce large amounts of carbon; when the material in the molten state, the carbon elements began to infiltrate into the white layer. Figure 2 EDM machining the substrate material composition analysis before and after EDM processing component of the white layer EDM Figure 2 shows the substrate material before processing component analysis, and the white layer after EDM processing component analysis. Can be seen from the figure, EDM processing components later than the EDM machining of carbon substrate materials before the elemental composition of carbon is much higher. White layer below, the heat affected zone. White layer of the region affected by the impact of carbon is very small heat effect only reached, not reached the melting point temperature. At this point, the heat affected zone still retains the microstructure of parent metal structure, because its absorption is not enough to change the structure of the temperature level. Under the heat affected zone is still in the base metal, this region has not been the impact of EDM processing. Figure 3, the white layer in the formation of tiny cracks in the sections Small cracks Mold maker is the main concern of small cracks appear in mold number. Figure 3 shows, in white layer, minute cracks occupied the absolute dominance. If this layer is too thick, or not through more sophisticated EDM machining or polishing to remove, then in some applications, this small crack will cause premature failure of components. And the existence of these cracks will reduce the material corrosion resistance and resistance to fatigue. Therefore, in evaluating the performance of EDM machining technology, the surface integrity is a primary consideration, EDM machining of the main objectives must be established on the basis of such a condition: the need to prevent this. Generated by the EDM machining of tiny cracks because of EDM processing cycle caused by thermal stress. The depth of cracks in part by EDM process control, no doubt, when the spark density increases, the white layer depth also increases. This also makes the cavity appear to increase the number and size cracks. Clearly, by the EDM process affects the surface integrity of today's EDM can also be used to control power supply technology. Affect the surface integrity of the special parameters, including voltage, current, time and duty cycle. These parameters can be controlled operation, so roughing, semi-finishing and finishing stages of the efficiency and integrity of the control surface the best. EDM process as the formation of white layer and the resulting small crack, it can be said that the white layer depth and density of spark energy are closely related. When the spark energy decreases, as we have seen, from the rough conditions into finishing conditions, the white layer depth has been reduced to appropriate and sufficient depth, and thus cracks are reduced. Figure 4 in the EDM machining process, current and time on the surface finish of Characteristics of the workpiece EDM surface integrity of the density is not affected only determining factor. Thermal conductivity of metal parts is also a key factor. Material with low thermal conductivity compared to the high thermal conductivity of the formation of white layer of small metal, small cracks are less. Phenomenon is caused by the above: a high thermal conductivity of the material surface to distribute the heat more. In this case, because of its high thermal conductivity and can be extended properties, copper alloy heat influence is thin, the resulting cracks are relatively small. In contrast, low thermal conductivity material, such as tool steel. The heat affected the level of thick, cracks are also generated more, because when the material in the heat to the surrounding area before the spark density stay longer in the spark zone. Ablation of carbon will have another problem, because this material is very brittle, showing a higher than other materials, the thermal characteristics of brittle fracture. Some people think that this material has high thermal conductivity; However, the carbide is tungsten carbide, or silicon carbide particles bonded with cobalt binder made from. It is because the binder has a high thermal conductivity, so this area greatly affected by the EDM process in order to replace the carbide itself. Spark energy makes this binder decomposition, the carbon particles released into the cracks. Surface finish and integrity Surface finish and surface integrity of the cavity is a measure of the quality of two different factors, but the characteristics of two indicators in the mold plays an important role in both. Machine parameters on sub-level of integrity of the cavity has a great influence, their surface finish is also significant. Figure 4 shows the EDM machining process, current and time on the surface finish of the film I am an expert from uhpbulb.com, while we provides the quality product, such as panasonic projector bulb , movie projector bulbs Manufacturer, dimmable led bulbs,and more.
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