1. Place a pattern in the sand to create a mold.
Make a reusable pattern that has the same shape as the final product. Leave a small allowance to accommodate for thermal shrinkage. Patterns can be made from different materials, depending upon the number of sand casting tolerances we want to include.
2. Incorporate the pattern and sand in a gating system.
After making the pattern, a sand mold is created by placing the pattern inside the sand blocks.
3. Remove the pattern.
The mold is generally shaped in two halves: the upper half is called the cope and the lower half is called the drag. Once the sand tightly holds up, the two halves are separated, and the pattern is removed. Then the two halves are joined back together, leaving a cavity with the same shape as the pattern.
4. Fill the mold cavity with molten metal.
In the next step, molten metal is poured into the mold cavity. The molten metal fills the cavity, as well as the runner and riser pathways.
5. Allow the metal to cool.
6. Break the sand mold away and remove the casting.
Once the metal cools, shake up the sand block, allowing the solidified metal product to fall out. Most of the sand is recovered and reused for further casting. Gates, runners, and risers are separated from the casting part, and other post-casting processes such as machining and grinding are applied for the final size and surface finish.