Shell casting process and characteristics

Shell casting process

The shell casting process offers better surface finish, better dimensional tolerances, and increased throughput due to reduced cycle times compared to regular sand casting processes. Materials available for this process are cast iron, aluminum and copper alloys. The shell forming process provides cost-saving solutions for difficult shapes, pressure vessels, weight-sensitive parts and castings requiring superior surface finish.

The shell casting process is also known as pre-coated resin sand casting process, hot shell casting or core casting process. The main modeling material is pre-coated phenolic resin sand, which is more expensive than green sand and furan resin sand. Moreover, this sand cannot be recycled.

Features of shell casting:

The cost of shell iron castings is higher than sand casting. However, shell castings have many advantages such as tighter dimensional tolerances, good surface quality, and fewer casting defects. Using resin sand to make thin shell molds or shell cores can significantly reduce the amount of molding sand used. The castings obtained have clear outlines, smooth surfaces, and precise dimensions, and can be processed without or with only a small amount of machining. Therefore, shell casting is particularly suitable for castings of various alloys with high dimensional accuracy requirements, thin walls and complex shapes, and high-quality surface finish requirements, because this process has better surface finish and more precise tolerances than sand casting. However, the resin used in shell casting is expensive, the template must be precisely processed, and the cost is high. It also produces a pungent smell during pouring, which to some extent limits the wide application of this method. The resin sand thin shell core can be used with ordinary sand molds or metal molds to produce various castings. Shell casting can also be used for the manufacture of actual parts, but since the molds are not reusable, this method is not suitable for mass production.