It's all about service — General Foundry Service

Green Sand Castings

The green sand process is the oldest among General Foundry’s capabilities, specializing in simple or complex shapes, ranging from fingernail size all the way to 150 pound castings/parts. Green sand is our most economical process and is known as green sand because there are no chemical additives, just clay, water and sand. Furthermore, the sand is recyclable and it really is the moisture content that binds or holds the sand together. Our green sand is an olivine base sand, which is a mined sand from Washington (state), and very fine grain. Our 125-150 RMS surface finish, leads the industry for surface finish on sand castings and helps us achieve that “class A” medical device finish many customers want. The thinnest wall section (geometry dependent) for a green sand casting is .125”, most thin walled components will be made closer to .160”. One common misconception about green sand castings is they cannot be cosmetic. We are breaking that stigma everyday with clean metal (through our degassing program), a machined smooth tool and very fine grain sand. Cosmetic geometries, including customer facing/touching components like handles, are among our sweet spots.

 

 

The green sand process is as follows:

- create sand shell or CO2 cores
- pack sand against the positive pattern on both sides of the tool
- remove mold halves from tool
- insert any cores in mold halves (creating undercuts and/or hollow features)
- close mold halves on top of each other and pour metal
- shake out (off) sand from solid metal geometry