During the production process of zinc alloy die casting transmission bracket, pore defects will seriously weaken its structural strength and performance stability. To avoid pores, it is necessary to control them systematically from multiple links.
The selection and processing of raw materials are the primary checkpoints to avoid pores. The purity and impurity content of zinc alloy directly affect the quality of die casting. Excessive impurities will produce gas at high temperature, increasing the risk of pores. Therefore, it is necessary to select high-quality zinc alloy raw materials and ensure that their composition meets the process requirements. At the same time, the raw materials should be fully dried before being put into use to remove the adsorbed moisture, because the moisture will quickly vaporize at high temperature to produce a large amount of gas, which is very easy to form pores.
The design and manufacture of die-casting molds are crucial to pore control. Reasonable mold structure can guide the smooth flow of molten metal and reduce gas entrapment. The design of the exhaust system of the mold needs to be carefully considered, and sufficient and appropriate exhaust grooves and exhaust holes should be opened in the parts where gas is easily trapped, so that the gas in the cavity can be discharged in time. The roughness of the mold surface should not be ignored. A too rough surface will hinder the flow of molten metal, making it difficult to discharge gas, while a too smooth surface may affect the adhesion of the molten metal, so it is necessary to grasp the degree of mold surface treatment.
Precise control of die-casting process parameters is the key to avoiding pores. During the die-casting process of zinc alloy die casting transmission bracket, if the die-casting speed is too fast, the molten metal will quickly flow into the cavity and draw in a large amount of air; if the speed is too slow, the molten metal may solidify prematurely, which will also cause the gas to be unable to be discharged. The injection pressure must also be set reasonably. Insufficient pressure cannot compact the metal and gas will remain in it; excessive pressure may cause the molten metal to splash and introduce new gas. In addition, the pouring temperature will also affect the generation of pores. Too high a temperature will aggravate the precipitation of gas in the molten metal, and too low a temperature will deteriorate the fluidity and make it difficult for the gas to be discharged.
Fully preheating the mold and spraying a release agent before die casting are important auxiliary measures. Zinc alloy die casting transmission bracket mold preheating can reduce the temperature difference between the molten metal and the mold, slow down the cooling rate of the molten metal, make it flow more smoothly, and facilitate gas discharge. The reasonable use of the release agent can not only help the casting to be demolded smoothly, but also form a thin insulation layer on the surface of the mold to play a buffering role. However, excessive or uneven spraying of the release agent will produce volatile gas, which will increase the risk of pores. Therefore, the spraying amount and uniformity need to be controlled.
The purification of the molten metal should not be ignored. Degassing the zinc alloy liquid before die casting can effectively reduce the gas content. The common degassing method is to introduce inert gas into the molten metal to fully mix it with the gas impurities in the molten metal and discharge it. At the same time, avoid exposing the molten metal to the air for a long time to prevent it from absorbing gas again, and minimize the stirring of the molten metal, because excessive stirring will aggravate the involvement of gas.
The skill level and standardized operation of the operator also have a great impact on pore control. Skilled operators can flexibly adjust the die-casting parameters according to actual conditions, and promptly discover and deal with abnormal conditions that may cause pores. Strictly abide by the die-casting process regulations, complete the mold preparation, molten metal treatment, die-casting operation and other links in sequence, and do not simplify the process arbitrarily to minimize the possibility of pores.
The later casting processing is also critical. For the formed zinc alloy die casting transmission bracket, appropriate heat treatment processes, such as stress relief annealing, can be used to further release the gas inside the casting and improve the organizational properties. In the post-processing processes such as grinding and polishing, attention should also be paid to the operation methods to avoid the formation of new pores or damage on the casting surface due to improper operation, so as to ensure that the final product quality meets the standards.
