The Metal Casting Process Explained

Metal casting – the modern process with ancient roots and arguably the earliest and most influential industrial process in history.

Metal casting is the process of pouring liquid metal into a mold to achieve the desired shape. The oldest known metal casting is that of a copper frog, believed to have been produced in 3200 BCE in Mesopotamia. Later, around 2000 BCE, Iron was discovered, but it was not until around 700 BCE that the Chinese developed the first production of cast iron. It was also the Chinese, in 645 BCE, who invented the sand molding process of casting metals.

Interesting to note that it was around 500 CE that the first cast crucible steel was produced. However, the technology was lost until 1750 when Benjamin Huntsman reinvented it in England. A crucible is a ceramic pot with refractory properties (materials that are used in linings for furnaces, kilns, incinerators, and reactors), typically made of clay in which metal is melted for casting.

Over the past 2,645 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 although, innovations like the General Kinematics’ VIBRA-DRUM® Sand Casting Conditioner have made finished products more refined and valuable.

The Casting Process

The first step is Patternmaking: where an object is designed. This step is only necessary for industrial part making where precise calculations are needed to make pieces fit and work together.

Step two is Core making: where the pattern is sculpted into a three-dimensional shape. Many times, wood, clay, or plastic is used for this process so that the core can be measured for accuracy before the final product is cast.

Step three is the creation of a Mold. Think about walking on the beach toward the ocean and seeing your footprint in the wet sand. Your foot would be the core and the impression left in the sand is the mold of your foot. In casting, a “green sand,” which can be hardened inside a “flask,” is commonly used. However, in industrial applications, a two-piece, non-destructible, metal mold is created so that it can be used repeatedly to cast identical parts.

Step four is the Pouring of the liquid metal into the mold where it is allowed to cool.

Step five is the final step, whereby 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.

To assist in this process, General Kinematics has developed the VIBRA-DRUM® Sand Casting Conditioner which excels at cooling, equalizing, and reclaiming sand from castings. The machine is revolutionary in its high volume mold and sand handling for foundry applications gently tumbling the sand off of castings while simultaneously cooling sand temperatures and evaporating moisture to provide a clean cast and sand ready for the reclamation process.

Modern Day Castings

Today, nearly every mechanical device we use, from automobiles to washing machines are manufactured using metal parts that were cast. The difference between today’s cast metal products and those that were manufactured even 100 years ago, is the precision and tolerances that can be achieved through the computerized automated design process and modern methods for producing the detailed cores and molds.

Throughout the centuries, various combinations of raw materials have been developed to produce various metal types. Some cast products are used in engines that require a high tolerance for heat and cold. Cast iron pipe must resist corrosion and high pressures. Other cast parts must be lightweight but durable. In many applications, parts are designed to allow for precise tolerance between expansion and contraction. The advancement in the quality of cast metal products starts with the quality of the mineral product itself.  

Proud to serve the Foundry Industry

General Kinematics is proud to be a leading manufacturer of automated vibratory processing equipment that has innovated alongside the foundry industry for nearly 60 years. To get more information about all of the General Kinematics foundry equipment, contact us today!