In the early stage of using the extrusion mold, a reasonable surface nitriding process must be performed on the mold. It should be noted that the surface nitriding can not be completed in one time. During the mold service, repeated nitriding must be performed 3-4 times. Generally, the thickness of the nitriding layer is required to be about 0.15mm. The mold cavity must be cleaned, and no alkali residue or foreign particles can be left. In general, the number of nitriding times of the mold does not exceed 4-5 times. It should be noted that the nitriding can only be performed through a suitable production process in the early stage of nitriding.
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6. The working belt must be ground and polished before the mold is placed on the machine. The working belt is generally required to be polished to the mirror surface. The working belt before the mold is machined must be ground and polished. The working belt is generally required to be polished to the flatness and verticality of the mirror facing the mold working belt before assembly. The quality of nitriding determines the finish of the working belt to a certain extent. The mold cavity must be cleaned with high-pressure gas and a brush, and there must be no dust or foreign matter, otherwise it is easy to pull the working belt under the driving of the metal flow, causing the extruded profile products to have surface roughness or scratches.
7. The mold holding time during extrusion production is generally about 2-3 hours. When using the mold, there must be a mold support, mold sleeve and support pad matching the mold to avoid the exit surface of the mold and The support pad contact surface is too small, which can deform or crack the mold.
8. Use the correct alkaline washing (boiler) method. After the mold is unloaded, the mold temperature is now 500 ° C. If the mold temperature drops rapidly, the mold is prone to cracking. The correct method is to wait for the mold to be unloaded, then place the mold in air to 100 ° -150 ° C and then immerse it in alkaline water. After the extrusion is completed, the extruding rod is retracted before the extruding cylinder, and the remaining pressure remains in the extruding cylinder, and then the extruding cylinder is retracted. At the same time, some residual aluminum in the mold orifice can be pulled out with the remaining pressure, and then alkali cook.
9. The use of the mold from low to high and then low use strength. In the middle of the use of the mold, since the performance of the mold is basically in a stable state, the use strength can be appropriately increased. In the later period, the metal structure of the mold has begun to deteriorate, and fatigue strength, stability and toughness have entered a downward curve after long-term production and service. At this time, the use strength of the mold should be appropriately reduced until the mold is scrapped.
10. Strengthen the use and maintenance records of the die in the extrusion production process, improve the tracking records of each set of molds, and strengthen the use and maintenance records of the die in the extrusion production process to facilitate management.
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