If you're familiar with metalcasting processes, you probably already know a lot of these words. Feel free to skip to the next post if you're feeling confident. But if you ask me, the same credo that applies to metal casting applies to learning about metal casting: "Better safe than sorry."
On the other hand, if you're knee-deep in casting terminology and can't seem to tell your risers from your ejector pins, this is the post for you. Read on for a primer on the terms and ideas involved in shell mold casting. We'll cover all of these concepts in more detail in later posts from the Introduction to Shell Molding series. Or, click below to download our printable Shell Mold Process Whitepaper.
Glossary of Key Terms in the Shell Molding Process
Cope: the top half of a two-part casting mold.
Core:a preformed sand shape inserted into a mold to form the interior of a casting, or a hollow part.
Corebox:a tooling used to produce a core.
Drag: the bottom half of a two-part casting mold.
Draft: taper on the vertical sides of a pattern or corebox allowing the core or sand mold to be removed without distorting or tearing the sand.
Ejector Pins:protruding attachments that push the mold away from the pattern after the sand has hardened.
Green Sand Molding:a common casting process, using moist, clay-bonded molding sand.
Investment Casting:a casting process involving wax and ceramic, allowing for smooth finishes and tight tolerances.
Mold:a rigid frame into which liquid metal is poured to form a casting.
Pattern:a replica of the part to be cast, used to shape the mold.
Riser:a reservoir built into the mold, placed to prevent parts from shrinking during cooling.
Runout:when liquid metal leaks from a defective or poorly sealed mold.
Shakeout:the process of vibrating molds-casting combinations in order to separate the mold from the casting.
Shell molding:a casting process that uses a thin layer of resin-bonded sand to form a mold. See pp.
Tree:a cluster of wax or plastic patterns mounted together during the investment casting process.
Venting:allowing gas to escape from a mold, either through microscopic gaps in the sand, or through pre-planned channels.
There you have it: a quick, easy introduction to the important terms used in the shell molding process. For more terms from our metal casting glossary, check out our glossary resource. At this point, you might be curious how all these ideas fit together. Read on in the Intoduction to Shell Molding blog series to get the full picture.
Jeff Cook is Chief Sales and Marketing Officer for Eagle Alloy in Muskegon, MI. While enlisted in the Marine Corps Reserves, he began working at Eagle Alloy in 1986 as a snag grinder on 3rd shift after his father told him to “Get a job!” Jeff is past President of the American Foundry Society. His passions include educating young people on the careers and advancement available in the metalcasting industry.