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How to solve the problem of airtightness of die castings
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Regarding the problem of airtightness of die-casting parts, poor air-tightness may cause various adverse reactions of the die-casting parts. The poor air-tightness detection of the die-casting castings is when pressure is applied to the die-casting parts, and pressure is leaked from the inside or the outside of the die-casting castings, possibly The performance is oil leakage, air leakage, water leakage, etc. Die-casting air tightness is one of the more difficult problems in the defects of die-casting parts. The cause may be the defects caused by the combination of various defects.Firstly, the cause of the poor airtightness of the die casting is analyzed: the casting is immersed in water, the inner cavity of the casting is filled with compressed air, and the compressed air passes through the passage formed by the inner surface defect and the outer surface defect of the casting to reach the water surface, and bubbles appear to exhibit airtightness. Poor detection, the reason for poor air tightness detection is caused by a combination of various casting defects.
Solution:
1. Select a reasonable pressure chamber fullness: When the punch diameter and the die casting machine are selected, the weight of the molten metal contained in the pressure chamber is also a certain value, but the weight requirements of the molten metal poured in each casting are different. . If the volume of molten metal poured into the pressure chamber is insufficient (that is, when the pressure chamber is low), the gas in the pressure chamber cannot be removed as soon as possible during the injection, and the turbulent state is formed under the high-speed push of the injection piston. The flow is so that it is easy to get caught in the gas, resulting in defects such as pores and insufficient pouring. At the same time, due to the presence of excessive scale in the pressure chamber, the skin is easily formed inside the casting, resulting in a decrease in the local strength of the casting, and leakage is likely to occur under the action of a large leak pressure. Therefore, selecting a reasonable filling degree of the pressure chamber can effectively reduce the porosity defects in the casting, thereby reducing the gas leakage rate of the casting.
2. Examples of improving the airtightness of die-casting castings: When strict, 100% of leaks must be detected. Otherwise, oil leakage will occur during use, affecting the normal use of the vehicle. Guaranteed air tightness in the production process is quality inspection. Focus. In the early mold design, since airtightness was not considered as a major problem, severe cracks appeared on the surface of the mold, and local strain was also severe, which further increased the air leakage rate of the casting.
Solving the problem of poor airtightness detection of castings is difficult in die casting production, and the cause may be caused by various casting defects. Therefore, in dealing with the phenomenon of poor air tightness, the nature, process, and mold of the alloy should be investigated step by step to find out the main reason and take measures in order to effectively improve the airtightness of the die casting.
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