Centrifugal casting is a process where molten metal is poured into a rotating mold, causing the metal to be distributed and solidify against the mold walls under the influence of centrifugal force. This method is divided into two main categories: true centrifugal casting and semi-centrifugal casting. True centrifugal casting is used for making parts with a symmetrical axis, such as tubes and rings, without the use of cores. Semi-centrifugal casting, on the other hand, employs a central core and is used for parts that are symmetrical but require detailed features on the axis, such as wheels and pulleys.
Advantages of Centrifugal Casting
- High Material Purity and Quality: The centrifugal force drives impurities and inclusions toward the center of the casting, which can be machined away, resulting in a part with superior mechanical properties and cleanliness.
- Good Mechanical Properties: The rapid cooling and solidification under pressure enhance the mechanical properties of the cast product, making it denser with a fine grain structure.
- Versatility in Size and Shape: Centrifugal casting is adaptable to a wide range of sizes and shapes, from small rings to large cylindrical parts.
- Efficient Material Utilization: The process is material-efficient, as the amount of metal poured can be closely controlled to match the part volume, reducing waste.
- Low Equipment and Mold Costs: Compared to other casting methods, centrifugal casting often requires less complex molds and can be more economical for certain shapes and quantities.
- Reduced Need for Secondary Operations: Due to the high quality of the surface finish and the precision of the casting, there is often a reduced need for secondary machining and finishing operations.
Disadvantages of Centrifugal Casting
- Limited to Symmetrical Parts: True centrifugal casting is primarily limited to parts that are axis-symmetrical, which restricts the range of products that can be manufactured using this method.
- Equipment Costs: While the molds might be less expensive, the machinery for centrifugal casting can be costly, particularly for large-scale operations.
- Not Suitable for Very Complex Geometries: Although semi-centrifugal casting can produce parts with some level of complexity, extremely intricate designs are not well-suited to this method.
- Safety Concerns: The operation involves high-speed rotation of molten metal, which can pose safety risks if not properly managed.
- Quality Control: While the process can produce parts with high internal quality, surface defects such as anisotropy induced by the flow of metal and centrifugal force can occur, requiring careful quality control.
- Size Limitations: Although centrifugal casting can produce a wide range of sizes, the maximum size is limited by the capacity of the centrifugal casting equipment.
Centrifugal casting is ideal for applications requiring high-quality, dense, and clean materials with good mechanical properties, such as pipes, bearings, and bushings in the water, gas, and petrochemical industries. The choice to use centrifugal casting should be based on an evaluation of the specific requirements of the part, including shape, size, material properties, and the desired quality of the final product.