Centrifugal Casting Eliminates Mid-wall Defects
- The centrifugal process does not rely on discrete risers or feed points to ensure the absence of trapped porosity. Rather, the inner diameter remains fully liquid during the solidification process, resulting in a continuous supply of metal to feed areas of contraction.
- Unlike conventional gravity or static castings that chill from both the inside and outside surfaces and risk trapping mid-wall shrinkage, centrifugal castings solidify from the outside surface inward. The result is a part consistently free of shrinkage cavities, gas pockets, and blowholes.
Centrifugal Casting Controls Impurities
- Unique to the centrifugal process is the high force that effectively isolates less dense substances in the casting’s bore area. These impurities are later machined away, leaving a defect free part. Molten metal is fed into a rotating mold where a centrifugal force of up to 100Gs is applied to the metal. Centrifugal force is critical for this process. The Gs produced are dependent on the RPM and diameter of the die.
- The centrifugal force pushes high density metal against the mold sidewall while lower density components migrate or "float" toward the I.D. These lower density items include metal oxides, sulfides, gas, and other impurities that would otherwise have been inclusions in the casting. This phenomenon is termed “secondary refining”.