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Green Sand: A Classic Casting Recipe

Casting Chronicles

The history of humanity is defined by man’s relationship with the material world. Man’s ability to make tools from metals has changed our historical trajectory.

A copper frog from Mesopotamia (modern-day Iraq) dating back to 3200 BCE is the oldest known casting. Farm tools made of cast iron were used in China in 600 BCE. In the Middle Ages, metal casting was widely used for making bells and artillery. Fast forward to the nineteenth century, iron and steel manufacturing underpinned the industrial revolution.

According to recent estimates published by the American Foundry Society (AFS), most people in the United States are rarely more than ten feet away from a metal casting: metal castings continue to permeate our lives in the Age of Plastic. Metal castings are indispensable to our engineering feats—automobiles, aerospace, construction equipment, machinery, house-hold appliances, medical devices, hardware, water industry, and other infrastructure. This year, in the United States, sales of metal castings will generate thirty-three billion dollars in revenue.

Casting: A Kaleidoscopic View

A casting is a metal part made by pouring molten metal into a mold, allowing it to solidify, and extracting the final casting. Metal castings are predominantly produced in sand molds. Sand molds are expendable, or single-use, molds that are destroyed after retrieving the casting.

Green sand is the most used molding medium; green sand is moist foundry-grade sand. Interestingly, green sand is not green in color.

Green sand molds are made from three ingredients—sand, water, and clay binders. The molds are fabricated by compressing the sand mixture around the pattern. Ferrous metals including various types of iron and steel are primarily cast in green sand molds. Non-ferrous metals, such as aluminum, copper, bronze, magnesium, and zinc, can also be cast in green sand molds.

What makes casting in green sand molds a timeless technology?

  • Versatile:  green sand can be molded to produce complex castings with extensive gating systems.
  • Tougher:  green sand withstands high temperature; the molds retain their shape when the molten metal is poured
  • Greener: casting with green sand is a sustainable process; the sand is recovered and reprocessed after every casting cycle and the metal scraps are recycled in an endless loop.
  • Leaner: the abundance of sand makes the process cost-effective.
Green Sand

Sand casting is constantly evolving, the new wave in the field is 3D printing smart sand molds. Additive manufacturing or 3D printing of sand molds is in its infancy and promises great potential. By all indications, sand casting is here to stay!

Casting (De)coded

A sound casting begins with a flawless mold. Green sand mold production is a world of contrasts—Simple, yet sophisticated; Mundane, yet masterful.

At THORS eLearning Solutions, we create courses that encapsulate the rich lifetime experience of our experts and provide valuable insights on mold making and producing quality castings. We offer a suite of high-quality casting courses presented in a visually rich, interactive, and engaging fashion. THORS is a trusted training resource to maximize the potential of your workforce.

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Castings

Aluminum: Driving the Decade

The first two decades of this century witnessed the dramatic fall and rise of the automotive industry. We cruise into the new decade with technological advances defined by fuel-efficient and autonomous vehicles.

Emission regulations and fuel economy mandates are defining the design parameters of the mobility market.  Automakers are increasingly adopting the production of lightweight vehicles for improving fuel efficiency. Aluminum—durable, lightweight, and high-strength material that can be infinitely recycled­—emerged as the “material of choice” for automobile components.

Permanent Mold Aluminum Castings

Aluminum and the Auto Industry: Past Milestones and Future Prospects

  • Dürkopp introduces the first sports car with an aluminum body in 1899
  • Carl Benz develops a car engine with aluminum parts in 1901
  • British Land Rover produces V-8 engine blocks with aluminum cylinders in 1961
  • Audi mass produces full aluminum body cars in 1994

Today, necessity and innovation have accelerated the use of aluminum in vehicle construction than ever before. According to a report published by Mordor Intelligence, the demand for die-cast aluminum parts is projected to reach USD $59,741.23 million in 2024.

Aluminum: Metal to Manufactured Solution

To meet the auto industry’s ongoing demand for aluminum components, about $2 billion has been invested in the aluminum casting industry since 2013. The casting process transforms the raw aluminum into a usable component. The common methods of casting aluminum include vacuum process, investment casting, permanent molds, and die casting techniques.

Vacuum process and investment casting are expendable casting processes where the mold is destroyed after each casting cycle. Vacuum process, or V-process, is a modified sand-casting process where the mold sand is held together by vacuum, instead of conventional binders. The parts fabricated using the vacuum process have excellent dimensional accuracy and superior surface finish. Investment casting, or lost-wax casting, involves controlled removal of pattern material from the mold and replacing it with the molten metal. Intricate parts that meet tight tolerance requirements are manufactured by investment casting technique.

Permanent molds and die casting methods use reusable molds. Permanent molds, or gravity die casting, harness the potential of gravity to gradually draw the molten metal into the mold. Low pressure and high pressure die casting methods to employ controlled pressure systems to force the metal into the mold. Castings manufactured by permanent mold and die casting methods have a finer surface finish.  Permanent mold casting and die casting methods are more popular as they have a high production rate.

The footprint of the vacuum process is on the rise!

eLearning Meets Manufacturing

In addition to its application in the auto industry, aluminum castings are integral to the airline, military, medical, and energy sectors. This surge in demand for aluminum castings has led to a corresponding job growth in the manufacturing segment. THORS eLearning Solutions offers a series of Aluminum Casting Courses that are an asset to casting manufacturers. The appealing visuals and interactive content support workforce training and skill development on the various casting operations.

Visit THORS Academy to see a full list of current courses.

Contact us, We would love to hear from you and discuss your training needs.