​ Common Defect Troubleshooting of Aluminum Die Casting: Porosity, Cracks, Shrinkage?

Common Defect Troubleshooting of Aluminum Die Casting: Porosity, Cracks, Shrinkage? Comprehensive Solution Analysis

Aluminum die casting is widely used in automotive, household appliance and other fields due to its advantages of high efficiency, precision and lightweight. However, defects such as porosity, cracks and shrinkage are prone to occur during the production process, which directly affect the strength and service life of products. Mastering scientific troubleshooting methods and solutions is the key to improving the qualification rate of aluminum die castings.

Porosity defects are mostly caused by gas-containing melt, poor mold venting or coating volatilization. During troubleshooting, first check the aluminum melt smelting process to ensure thorough degassing and refining, and avoid excessive smelting temperature which increases gas solubility; then check the mold venting system, clean impurities blocking the venting grooves, and add venting channels if necessary. In addition, selecting low-volatility and high-temperature-resistant die casting coatings to reduce gas generated by high-temperature decomposition of coatings can effectively reduce the probability of porosity.

Crack defects are mainly caused by uneven cooling, unreasonable mold design or improper demolding. If hot cracks appear in castings, they are mostly due to large differences in cooling speed. It is necessary to optimize the mold cooling system to ensure uniform cooling of all parts of the castings; cold cracks may be caused by excessive demolding force or stress concentration in the casting structure. The demolding mechanism should be adjusted, and the sharp corners and sudden thickness changes of the castings should be optimized with fillets. At the same time, control the die casting process parameters to avoid excessive internal stress during alloy solidification.

The core cause of shrinkage defects is insufficient feeding during the volume shrinkage of the alloy during solidification. During troubleshooting, first check the gating and riser design to ensure that the gating and riser can effectively feed the last solidified part of the casting; adjust the die casting process, appropriately increase the injection pressure and holding time to promote full filling of the melt. In addition, strictly control the alloy composition to avoid impurities affecting the uniformity of solidification shrinkage, which can reduce shrinkage defects.