What is Metal Casting?

Modern metal casting has historical precedent. In the metal casting process, metal is poured into a mold cavity, cooled, and then shaped into the desired shape before being removed from the mold. The oldest and most important industrial process in history is probably metal casting. Many of the metal items we use on a daily basis are made with it, including school bus pedals, railway wheels, automobile parts, and more. Additionally, metal recycling serves as a cost-effective source of raw materials for metal casting foundries, greatly lowering the amount of discarded metal that may otherwise wind up in landfills.

The History of Metal Casting

The oldest metal casting that has been discovered is a copper frog, which is thought to have been created in Mesopotamia around 3200 BCE when copper was a widely used material. Later, iron was found, probably around 2000 BCE. The first cast iron production, however, did not start until roughly 700 BCE in China. It's interesting to note that in 645 BCE, China also developed the sand molding technique for casting metals.

The crucible process, a technique for producing fine or tool steel, has appeared and disappeared in numerous locations across the globe since the first century CE. The technology first appeared in India and central Asia before spreading to northern Europe around 800 CE, where it was used to make Viking swords. It wasn't until Benjamin Huntsman rediscovered it in England in 1750 that it was once again employed. Huntsman heated minute pieces of carbon steel in a closed crucible, which is a ceramic vessel with refractory properties that can withstand a high degree of heat. Huntsman attained a temperature hot enough to melt steel for the first time.

Over the past thousands of years, the casting of metals into usable objects has evolved to become more exact and automated, but the process at its core has essentially remained the same. Innovations in automation of foundry processes like the General Kinematics’ VIBRA-DRUM® Sand Casting Conditioner have made processing large quantities of castings easier as well as improved the quality of the castings. The machine is revolutionary in its high volume mold and sand handling for foundry applications.

The Metal Casting Process

Making patterns - A pattern is a copy of the casting's exterior. Typically, patterns are constructed of plaster, wood, metal, or plastic. For the production of industrial parts, where exact calculations are necessary to ensure that components fit and function together, patternmaking is crucial.

Coremaking - If a casting is hollow, the internal form is shaped to make it hollow using an additional piece of sand or metal (referred to as a core). Typically, cores are robust yet foldable, making it simple to remove them from the finished casting.

Molding – To visualize the metal casting process so far, imagine yourself walking on the beach toward the ocean. Look at a footprint you leave behind in the wet sand. Your foot would be the core, and the impression left in the sand is a mold of your foot. Molding is a multistep process that will form a cast around the pattern using molding sand. In casting, a mold is contained in a frame called a flask. Green sand, or molding sand, is packed into the flask around the pattern. Sand casting for metal is what this is. The design can be removed and the cast will remain once the sand is well compacted. As an alternative, a two-piece, unbreakable metal mold might be made, which could then be frequently used to cast similar parts for industrial uses.

Melting and Pouring Molten Metal—After being melted, the metal is poured into the mold's cavity and given time to set. Once set, the molds are vibrated to remove sand from the casting as part of the shakeout process. Because of its effective and smooth operation, equipment like our Two-Mass Shakeouts maintains high production output in industrial applications. Sand that has been removed is often collected, cooled, and recycled for use in subsequent castings. The VIBRA-DRUM® Sand Casting Conditioner improves this process of sand separation from castings by removing and cooling sand and castings and evaporating moisture, while alleviating the casting damage that is common during this point of the process. The end results are a clean cast and sand ready for the reclamation process.

Cleaning – In this final step, the cast metal object is removed from the mold and then fettled. During the fettling, the object is cleaned of any molding material, and rough edges are removed.