Aluminum alloy defect shrinkage often occurs in the thick parts of castings, or at the intersection of thick and thin. Sometimes the surface of the casting is whitish, in fact, it is shrinkage.
Reasons for Aluminum Alloy Defect Shrinkage
- Insufficient casting shrinkage during the crystallization process;
- The position of the introduced alloy liquid is wrong;
- The temperature of each part of the metal type is inappropriate and does not meet the principle of sequential solidification;
- Improper paint or peeling paint;
- Pouring temperature is too high;
- The pouring speed is too fast;
- The casting is cooling too slowly;
- The burrs of the casting are too large.
Solutions for Aluminum Alloy Shrinkage
- Set the Hot Top Casting Cap in the thick part of the casting, the size and height of the Hot Top Casting Cap should be suitable, to achieve later solidification, and to improve the feeding effect of the hot top casting cap;
- Inner runners are evenly distributed along the circumference of the casting, or supplementary runners are opened from the root of the riser for supplementary pouring;
- Adjust the temperature specifications of each part of the metal mold to facilitate the sequential solidification of castings;
- According to the different requirements of the working part of the casting and the position of the pouring riser, BN paint is selected, and the stripping material should be evenly supplemented;
- Properly reduce the pouring temperature;
- Slow down the pouring speed;
- In areas prone to shrinkage, copper cold iron or refractory plugs are embedded to accelerate cooling.
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