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How to make a Permanent mold?
High tolerance precision, no flash, super high surface quality, all of these criteria are the metal parts, die casting mold manufacturing process must meet some requirements. There is no doubt able to achieve this level of metal mold manufacturer, although there are several, but very few. Quality is the key. First, the mold design to have a good plan. This is the basis and key of the success or failure. It should include the excellent cooling water circuit layout and parting line locking device to prevent the dislocation of mold processing, and a good support for the mold cavity and core sidewall framework, which is suitable for a specific part off mode. The details of the design including the size of the mold parts, material selection, mold and mold cavity tolerances, surface quality and coating the gate and the flow, vent location and size, pressure sensor position. In the successful manufacture of MIM molds, mold release and cooling has become a key issue.
1, cavity / core steel:
Cavity / core steel used should be able to withstand the wear and tear caused by the compression molding material. Forming composite steel contact (including gate and runner), all with molded by high wear resistance of high chromium content and high hardness tool steel, such as D-2 or A-2 tool steel. H-13 steel can also be because of its high hardness, plating a layer of high hardness coatings. Those who do not molded composite contact details of the parts are available to the standard S-7 tool steel manufacturing.
2, close angle / slider:
MIM mold production process, the flash is a serious problem, the workers of the molding is a substantial problem. To prevent this problem, and good coordination of all closing angle and the sliding region is very important, the only way, in order to produce a high quality MIM parts. Scroll size mold manufacturers must be calculated by using the triangulation method, and then apply this knowledge to check yin and the yang side of the closure of the steel angle, to ensure that he calculated the size of ± 0.0001 tolerance range within. People need to maintain tolerance in general for the metal mold is already quite accurate, MIM molds for materials and parts of the flash is very sensitive, it is prone to flash. Plastic parts produce flash, it is easy to get rid of flash, but if it is metal, the flash will cause problems if the blade did. You must create a does not produce mold flash.
3, the vent depth:
In a variety of mold, in order to release internal gas produced by the molding material, the vent is crucial. He pointed out that, of MIM mold vent depth to differ materially from the injection mold. A typical plastic mold, depending on the molded resin may be everywhere, 0.0005 ~ 0.002 (1in = 25.4mm) deep vent MIM mold will definitely flash, MIM mold vent depths vent depth of between 0.0001 ~ 0.0002in, but may also change with the selection of molded composite metal material. Good feeding after the solidification process, the shrinkage is very low. To try to strengthen the shape to maintain the intensity of the extensive use of metal powder filler, the dosage is often close to 70% of the volume. To be able to obtain highly filled to the good mobility of the material, the use of low molecular weight and the binder, so that the MIM for the material to produce a high flash sensitivity, similar to many of the display characteristics of filled nylon material. Paraffin wax and polyethylene / glyceryl feeding acetyl feeding good features, but will affect the sensitivity of its higher flash.
4, and polished:
Another key area of the MIM parts surface quality of the molding area. Depends largely on the quality of the surface of the cavity and core tool steel, mold release from the mold cavity District in the compression molding process, the shrinkage rate is very low. Metal molded parts shrink and does not really happen, unless compression molding process after the passage of the binder material is extracted. Therefore, the polishing of the molding area is crucial. In general, the molded surface should reach 600 composite finish, may in rare cases to achieve the diamond finish.
5, and electroplating:
Such as chromium or nickel plating layer of high hardness will be able to enhance the efficiency of molding metal mold release process, combined with high-polished surface, so that it can produce better results. Some types of chromium and nickel added to the release agent, and its purpose is to improve their release characteristics.
6, the learning curve:
Mastered the basic knowledge, there are still more factors to consider, and then the order of progressive learning. MIM Another challenge comes from the raw materials, generally refers to the supply of materials. Contains a lot of very fine metal powder because of its internal, often close to 70% of the volume. Metal powder to create the final part. Plastic parts, metal powder to increase liquidity, to remove all injection molding. Powder with a little friction, hard tool to higher spindle speed processing. Because there is no high-speed machine tools, many mold makers had to resort to the ablation mode processing. However, it can not be left behind by a rough surface quality, because the MIM requires close tolerances. Different metals are basically the same mold manufacturing requirements, unless we sometimes need to insert a different rate of contraction. Referred to here is not inside the mold shrinkage. Shrinkage will occur only when out of parts from the mold and into the furnace. In the mold, the shrinkage is almost close to zero, every inch of the shrinkage rate of less than 0.001in, Therefore minimal shrinkage in the mold!
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