Why does aluminum alloy casting have defects such as pores and bubbles

Why does aluminum alloy casting have defects such as pores and bubbles

Among all metal products, the most widely used are aluminum alloy products. Like aerospace, automotive, communications and chemical industries, aluminum alloy products can be said to be common. With the more and more extensive range of use, the casting process continues to improve, and the quality of Jinan aluminum alloy casting parts has a higher standard. Basically, the surface of aluminum alloy castings is not allowed to have obvious defects such as cracks.

So what factors are related to aluminum alloy casting? All the casting factors in the casting process, alloy heating temperature, mold temperature, the complexity of the molding, the gating system and the gating shape, etc., will affect the molding of the aluminum alloy die casting.

In this paper, the defects of common die casting parts are taken as an example to analyze the causes of the defects of pressed castings.

Analysis of the causes of pores in aluminum alloy die-casting molding, first of all, poor refining degassing, casting temperature of liquid aluminum is generally about 600 degrees, at this temperature, the liquid hydrogen content is about 20 times the solid hydrogen content, then aluminum in the process of condensation, there will be a large number of gas generation, need to be released, so there will be a large number of irregular pores, This is the role of liquid aluminum refining degassing.

The second possible reason is the porosity caused by poor exhaust gas. For the porosity caused by poor exhaust gas, the exhaust channel of the mold should be improved, the mold exhaust gas should be cleaned in time, and the residual aluminum skin on the channel can be avoided.

Aluminum alloy die-casting molding will also have shrinkage pores, aluminum alloy shrinkage during solidification, the higher the casting temperature, the larger the shrinkage, due to the volume contraction of the porosity is present at the end of the alloy solidification site, irregular shape, serious network. Often in the product, it exists at the same time as the pores precipitated by hydrogen during solidification, there are shrinkage pores around the hydrogen precipitated pores or coiled pores, and there are filamentous or mesh pores around the bubbles that extend to the outside.

The end is the product wall thickness difference caused by excessive porosity problem, product shape often wall thickness difference is too large problem, in the center of the wall thickness is the solidification of liquid aluminum, is also the most easy to produce porosity parts, in the production process to fully consider the thickness of most of the casting temperature, cooling speed, similar to this from the mold design should consider the point cold, increase the cooling amount.

In order to solve the problems that will occur in the process of aluminum alloy die casting, it is necessary to use the aluminum alloy die casting die temperature machine to control the temperature of the die casting. The aluminum alloy die casting die temperature machine can preheat the mold, reduce the mold surface layer and internal temperature gradient at the beginning of production, and prevent the mold from cracking and failure due to abnormal temperature.

Aluminum alloy die casting die temperature machine preheats the die and maintains the temperature of the die in the initial production and production gap, reduces the hot die time, saves energy, speeds up the production schedule and improves efficiency. During the production process, the mold temperature is kept constant (heating and cooling), which can make the size and density of the die casting parts remain stable and ensure the stability of product quality.

Due to the heating and cooling effect of aluminum alloy die casting mold temperature machine, the amount of release agent can be reduced, the chill of the mold can be reduced, the thermal stress can be reduced, the crack of the mold surface can be delayed, and the service life of the mold can be extended, the use of cooling water can be reduced, the life of the mold can be extended, the die casting cycle can be saved, and the product can also have a certain inhibition effect on sticking, aluminum sticking and strain. Improve the appearance of the product and reduce the occurrence of defective products.

For Jinan aluminum alloy processing technology, the requirements are still relatively high. Aluminum alloy This metal can be used well in many occasions, but also in the processing industry, the competition is becoming more and more intense, and the product has become the most important indicator. A good quality product can make the enterprise get better development.