What is the resin pre-coated shell casting procedure?
Shell molding casting process is also called pre-coated resin sand casting process, hot shell molding castings or core casting process. The main molding material is the pre-coated phenolic resin sand, which is more expensive than green sand and furan resin sand. When the pre-coated sand is heated by the hot patterns, the sand will become strong shell to form the mold cavity, which will withstand the molten metal and alloys.
The pre-coated sand can not be recycle used. The shell molding castings have higher costs than sand casting. However, the shell molding casting parts have many advantages such as tighter dimensional tolerance, good surface quality and less casting defects.
Resin Pre-coated Shell Mould Casting Procedures
1- Design and Make Patterns.
The pre-coated resin sand needs to be heated in the patterns, so metal patterns are the necessary tooling to make shell molding casting
2- Make Pre-coated Sand Mold
After installing the metal patterns on the molding machine, the pre-coated resin sand will be shot into the patterns, and after heating, the resin coating will be molten, then the sand molds become solid sand shell and cores.
3- Melt the Cast Metal
Using induction furnaces, the materials would be melted into liquid, then the chemical compositions of the liquid iron should be analyzed to match the required numbers and percents.
4- Pouring Molten Metal
When the melted iron meet the requirements, then they will be poured into the shell molds. Based on different characters of the casting design, the shell molds will be buried into green sand or stacked up by layers.
5- Shot Blasting, Grinding and Cleaning
After the cooling and solidification of the castings, the risers, gates or additional iron should be cut off and removed. Then the iron castings will be cleaned by sand peening equipment or shot blasting machines. After grinding the gating head and parting lines, the finished casting parts would come, waiting for the further processes if needed.
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