Defects of Aluminum Alloy Die Castings and Their Solutions
At present, aluminum alloy is the most widely used alloy. It has been widely used in aerospace, automobile, communication, machinery manufacturing, shipbuilding and chemical industries. With the improvement of die-cast technology, there are also high standards and high requirements for the quality of aluminum alloy die castings, The surface of the casting is not allowed to have cracks, be short of materials, shrinkage porosity and any penetrating defects. What factors are related to aluminum alloy castings? All casting factors in the casting process such as alloy heating temperatures, mold temperatures, molding complexity, pouring systems and pouring shapes, will affect the molding of aluminum alloy die castings.
Take the common die-cast defect, that is gas hole, as an example, and briefly analyze the causes of die-cast defects. The reasons for the generation of gas holes in aluminum alloy die-castings is the poor refining and degassing. The casting temperature of molten aluminum is generally around 600 degrees. At this temperature, the liquid hydrogen content is about 20 times that of the solid hydrogen content. Then, in the condensation process of the aluminum industry, a large amount of gas will be produced, which needs to be released, so a large number of irregular gas holes will appear. That is why refining and degassing are required for aluminum liquids. Another possible reason is the poor exhaust. The exhaust channel of the mold should be improved, and the mold should be cleaned in time, so that the residual aluminum skin on the channel can be avoided.
Shrinkage holes also occur for aluminum alloy die castings. Aluminum alloy shrinks during solidification. The higher the casting temperature is, the more serious the shrinkage hole becomes. The gas hole caused by volume shrinkage existsß in the final solidification part of the alloy, which is irregular and has a shape of a mesh in a severe case. It exists with the gas hole due to the precipitation of hydrogen during solidification. There are shrinkage holes around the precipitation of hydrogen, and there are filamentous or mesh gas holes extending to the outside around the bubbles.
In addition, there is the problem of gas holes caused by excessive wall thickness difference of the product. The shape of the product often has the problem of excessive wall thickness difference. The center of the wall thickness is the place where the molten aluminum solidifies at the end, and it is also the most prone to gas holes. In the production process, it is necessary to fully consider the casting temperature and cooling rate of the thick and large parts, and the mold design should consider spot cooling and increase the cooling amount.
In order to solve the problems that may occur in the process of aluminum alloy die casting, it is necessary to use an aluminum alloy die-cast mold temperature machine to control the temperature of the die-cast part. The aluminum alloy die casting mold temperature machine can preheat the mold and reduce the temperature gradient of the mold surface and internals to prevent the failure of the mold due to cracking caused by abnormal temperatures.
The aluminum alloy die casting mold temperature machine preheats the mold and maintains the temperature of the mold in the initial production and production gap, reducing the mold heating time, saving energy consumption, speeding up the progress of production, and improving efficiency. In the production process, the mold temperature is kept constant (heating and cooling), which can keep the size and density of the die casting stable and ensure the stability of the product quality.
The amount of release agent used can be reduced, and the chilling of the mold can be reduced, reducing the generation of thermal stress, delaying the generation of cracks on the surface of the mold, and prolonging the service life of the mold due to the heating and cooling effect of the aluminum alloy die-cast mold temperature machine. Cooling water can be reduced, the service life of the mold can be prolonged. The die-cast time can be shortened. There is also a certain inhibitory effect on the product sticking to the mold, aluminum sticking and strain, improving the appearance of the product and reducing the generation of defective products.
Take the common die-cast defect, that is gas hole, as an example, and briefly analyze the causes of die-cast defects. The reasons for the generation of gas holes in aluminum alloy die-castings is the poor refining and degassing. The casting temperature of molten aluminum is generally around 600 degrees. At this temperature, the liquid hydrogen content is about 20 times that of the solid hydrogen content. Then, in the condensation process of the aluminum industry, a large amount of gas will be produced, which needs to be released, so a large number of irregular gas holes will appear. That is why refining and degassing are required for aluminum liquids. Another possible reason is the poor exhaust. The exhaust channel of the mold should be improved, and the mold should be cleaned in time, so that the residual aluminum skin on the channel can be avoided.
Shrinkage holes also occur for aluminum alloy die castings. Aluminum alloy shrinks during solidification. The higher the casting temperature is, the more serious the shrinkage hole becomes. The gas hole caused by volume shrinkage existsß in the final solidification part of the alloy, which is irregular and has a shape of a mesh in a severe case. It exists with the gas hole due to the precipitation of hydrogen during solidification. There are shrinkage holes around the precipitation of hydrogen, and there are filamentous or mesh gas holes extending to the outside around the bubbles.
In addition, there is the problem of gas holes caused by excessive wall thickness difference of the product. The shape of the product often has the problem of excessive wall thickness difference. The center of the wall thickness is the place where the molten aluminum solidifies at the end, and it is also the most prone to gas holes. In the production process, it is necessary to fully consider the casting temperature and cooling rate of the thick and large parts, and the mold design should consider spot cooling and increase the cooling amount.
In order to solve the problems that may occur in the process of aluminum alloy die casting, it is necessary to use an aluminum alloy die-cast mold temperature machine to control the temperature of the die-cast part. The aluminum alloy die casting mold temperature machine can preheat the mold and reduce the temperature gradient of the mold surface and internals to prevent the failure of the mold due to cracking caused by abnormal temperatures.
The aluminum alloy die casting mold temperature machine preheats the mold and maintains the temperature of the mold in the initial production and production gap, reducing the mold heating time, saving energy consumption, speeding up the progress of production, and improving efficiency. In the production process, the mold temperature is kept constant (heating and cooling), which can keep the size and density of the die casting stable and ensure the stability of the product quality.
The amount of release agent used can be reduced, and the chilling of the mold can be reduced, reducing the generation of thermal stress, delaying the generation of cracks on the surface of the mold, and prolonging the service life of the mold due to the heating and cooling effect of the aluminum alloy die-cast mold temperature machine. Cooling water can be reduced, the service life of the mold can be prolonged. The die-cast time can be shortened. There is also a certain inhibitory effect on the product sticking to the mold, aluminum sticking and strain, improving the appearance of the product and reducing the generation of defective products.
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