Common Defects and Solutions of Zinc Alloy Die Castings
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Publication time:
2024-08-22 10:47:56 *
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In the production process of zinc alloy die castings, due to the influence of various factors, some common defects may occur. Understanding these defects and their solutions is crucial for improving the quality of zinc alloy die castings.
I. Porosity
Porosity is one of the common defects in zinc alloy die castings. The formation of porosity is mainly due to the entrapment of gas in the molten metal during the die casting process, or when the mold has poor exhaust and the gas cannot be discharged in time and remains inside the casting.
Solutions:
Optimize die casting process parameters, such as reducing the injection speed and increasing the mold temperature, to reduce the possibility of gas entrapment in the molten metal.
Improve the exhaust system of the mold, increase the number and size of exhaust grooves to ensure that the gas can be discharged smoothly.
Conduct sufficient degassing treatment on the molten metal, such as using vacuum degassing or inert gas degassing methods.
II. Shrinkage cavity and porosity
Shrinkage cavity and porosity are defects caused by the volume shrinkage of molten metal during solidification. Shrinkage cavities generally appear in the thick parts of the casting, while porosity is distributed inside the casting.
Solutions:
Reasonably design the structure of the casting, avoid thick parts, and try to make the wall thickness of the casting uniform.
Adjust die casting process parameters, such as increasing the injection pressure and prolonging the holding time, to promote the feeding of molten metal.
Set up a cooling system on the mold to control the solidification sequence of the casting so that the molten metal can fully feed.
III. Cold shut
Cold shut is a defect formed when two or more streams of molten metal meet but fail to fully fuse during the filling process. The appearance of cold shut will affect the appearance and mechanical properties of the casting.
Solutions:
Increase the temperature and fluidity of the molten metal to ensure that the molten metal can fill smoothly.
Optimize die casting process parameters, such as increasing the injection speed and increasing the gate area, to improve the filling ability of the molten metal.
Preheat the mold to reduce the heat loss of the molten metal and improve the fluidity of the molten metal.
IV. Surface defects
The surface of zinc alloy die castings may have defects such as flow marks, patterns, and scratches. These defects are mainly caused by poor mold surface quality, unreasonable die casting process parameters, or improper operation.
Solutions:
Improve the surface quality of the mold, polish the mold to ensure a smooth mold surface.
Optimize die casting process parameters, such as reducing the injection speed and adjusting the spraying process, to reduce the occurrence of surface defects.
Strengthen the training of operators, standardize the operation process, and avoid surface defects caused by improper operation.
V. Dimensional deviation
Dimensional deviation refers to the difference between the actual size of the zinc alloy die casting and the designed size. The occurrence of dimensional deviation may be caused by low manufacturing accuracy of the mold, unstable die casting process parameters, or measurement errors.
Solutions:
Improve the manufacturing accuracy of the mold, use advanced processing equipment and technology to ensure the dimensional accuracy of the mold.
Stabilize die casting process parameters, strengthen the monitoring and adjustment of the die casting process, and ensure the dimensional stability of the casting.
Use accurate measuring equipment and methods to conduct strict dimensional inspection on the casting and find and correct dimensional deviations in time.
In conclusion, the common defects of zinc alloy die castings include porosity, shrinkage cavity and porosity, cold shut, surface defects, and dimensional deviation. By optimizing die casting process parameters, improving mold design and manufacturing quality, and strengthening quality control, these defects can be effectively reduced and the quality of zinc alloy die castings can be improved.
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