How can you minimize porosity and shrinkage in casting processes?

Design molds with proper gating and risering systems. Control pouring temperature and use clean, high-quality metal. Optimize cooling rates and apply directional solidification. Ensure adequate venting and consider vacuum or pressure casting. Use inoculants to refine grain structure and control mold temperature. Employ simulation software for process optimization. Implement post-casting treatments like heat treatment. Conduct rigorous quality control and inspections.

To minize the shrinkage and porosity of die casting, the most important is ensure the the refining and degassing quality of alloy smelting, alloy ignot surface and tools dry, recycle materails are clean. Select a good refining agent, degassing agent, control the melting temperature, avoid overheating, reduce the amount of gas in the metal melt, degassing treatment. Remove scum, bubbles and other oxides on the liquid surface in time to prevent gas from entering the die casting again. Second, raw materials should be stored in a dry environment, away from moisture.

Mold designed improved is another crucial factor to minimize the porosity and shrinage of the die casting part. 1). Ensure that the vent slots and overflow slots of the mold are in the correct positions. Filling the mold in sequence is conducive to the discharge of gas from the cavity, ensuring unobstructed exhaust to completely remove gas from the mold, especially at the final aggregation point of the aluminum melt where the exhaust passage must be clear. Use mold flow analysis software to analyze the flow of molten metal, avoiding turbulence before mold is building. 2). Incorporate a vacuum evacuation structure into the mold to facilitate better molten metal filling to minimize the porosity

With our 23 years' experience in die casting field, temperature control is the crucial point during production. Most of the current die-casting equipment is equipped with automatic temperature control, making it quite intelligent. However, relying solely on the equipment is not sufficient. 1). Add a mold temperature controller to the equipment to regulate the temperature in various sections of the mold, ensuring that the cooling initiation temperature is consistent. 2). Adjust production parameters and implement secondary pressurization during the casting process. This can reduce the proportion of porosity, resulting in a smoother product surface and stronger strength of the part.

Traditional die-cast products cannot undergo heat treatment, such as T5 or T6 processes. This limitation is because the porosity cannot be eliminated for tranditional die casting process, and it is only up to level 2. When these products undergo heat treatment, the internal sand holes expand and may cause the product to crack, ultimately affecting its performance and strength. However, with technological innovation, semi-solid die-cast products can undergo heat treatment. After heat treatment, the product exhibits improved strength.

Die-cast products exhibit different levels of porosity,and traditional die-casting processes are limited in eliminating porosity, reaching a maximum level of 2. Customers determine the desired porosity level based on their product's application and performance requirements before mold design. We design molds according to the specified porosity level and closely manage the production process. Upon completion, we conduct X-ray inspections to detect sand holes and perform air tightness tests in accordance with customer specifications.

Conduct regular audits of the casting process. This helps in identifying and rectifying any deviations that might lead to increased porosity or shrinkage. Continuous process improvement, based on these audits, has been a key aspect of quality control in my projects. Use high-quality raw materials with minimal impurities. Impurities in the metal can increase the likelihood of porosity and shrinkage defects. Ensuring the purity of raw materials has been a standard practice in my work. Manage cooling rates to control the solidification process. Rapid cooling can cause shrinkage porosity. In various projects, I've used controlled cooling techniques to reduce these risks.