At this point in the process, we have our part encased in sand, and we need to get it out. To see how the professionals do it, skip to 2:02 in the video below.
Yep, all you do is knock all the sand off of the part. This is one of major advantages of sand casting; parts can be created with extremely complex geometries. For example, if someone tried to cast an engine block with a permanent mold (made of metal) how would the part be removed? The part can't just be pulled out, and breaking apart a metal mold would be ridiculous. Thus sand is used because it's cheap, abundant and can be broken apart easily.
Secondary Processes
After removing the part from the mold, it will still has the gating system attached, as seen below. The processes used to remove the gating system are classified as secondary processes. Actually any process to refine the final part is a secondary process, this includes things like finishing or painting. Any molding operations produce a parting line, a line of extra material around the part where the cope and the drag meet. We see parting lines every day on all sort of objects, think of a water bottles, the line running down the side is a parting line. Many manufacturers use secondary operations to smooth down parting lines for cosmetic and safety reasons (they can be sharp).
Gating systems still attached to cast parts. The fat round part on the top is from the pouring cup.
Found here.
Found here.
This concludes the basic overview of sand casting. To learn more, watch the related videos on YouTube, go to Foundry101, or search Google. Good luck with sand casting and remember to always put safety first.
All information was gathered from the book Principles of Modern Manufacturing by Mikell P. Groover, from lectures done by Professor Michael Slifka, and from browsing YouTube videos.