Effect of Vacuum Degree on Pinhole of Vacuum Counter-Pressure Casting Molten Aluminum Alloy

During vacuum counter-pressure casting, the vacuumization is an important stage for thin-wall and complicated aluminum alloy castings. Through testing and an analyzing numbers of pinhole and pinhole grade of aluminum alloy samples under different vacuum degree, the effect of vacuum degree on pinhole of vacuum counter- pressure casting molten aluminum alloy is studied. The results indicate vacuum degree has greater effect on pinhole of molten aluminum alloy in vacuumizing process. The smaller vacuum degree is, the more numbers of pinhole of the samples are, and the higher pinhole grade of the samples is. Therefore, when vacuum degree is small, pinhole of molten aluminum alloy appears easily. So the vacuum degree doesn’t choose too small, but for thin-wall and complicated aluminum alloy castings, the vacuum degree doesn’t choose too big either. Appropriate vacuum degree is from 20 KPa to 40 KPa.