Basic knowledge of casting
The World of Castings that Supports Our Daily Lives
What is a casting?
A casting is a product made by melting metal, pouring it into a mold, and letting it cool and solidify.
Although we may not often think about it, castings are used in many aspects of our daily lives.
Here are some familiar examples:
The heavy-duty manhole covers seen on roads are typically made of cast iron.
Their weight and strength make them safe and durable—even under the pressure of passing vehicles.
Some frying pans and pots used in kitchens are made of cast iron.
Cast iron has excellent heat retention and even heat distribution, making it ideal for cooking.
Key components such as engine blocks and brake discs in cars are also made from castings.
Cast iron is chosen for these parts due to its high heat resistance and strength.
Many park benches and streetlamp poles are also made from cast iron.
Its excellent durability makes it suitable for long-term use in outdoor environments.
Castings are also used in statues, bells, and decorative vases.
The casting process allows for intricate designs and detailed expression, making it a perfect fit for artistic applications.
Castings are an essential part of modern life.
If you look around, you’ll start to notice just how deeply casting technology is embedded in our world.
Learning more about castings may also spark greater interest in the world of manufacturing.
History of casting
Casting is the technique of producing metal objects by pouring molten metal into a mold.
Here, we briefly introduce the history of casting—focusing on cast iron development.
c. 4000–1500 BCE
The Origins of Casting
The origins of casting trace back to around 4000 BCE in Mesopotamia, where molten bronze was poured into molds to produce various tools and vessels. Casting is one of humanity’s oldest manufacturing techniques.
An ancient Egyptian papyrus from around 1500 BCE illustrates craftsmen melting bronze in a crucible, using foot-powered bellows, and casting large doors—showcasing early industrial techniques.
Late Early Yayoi Period
Beginnings in Japan
Japan’s metal casting history began in the late Early Yayoi period, with the introduction of iron and bronze tools. Iron items were mainly forged and used for farming and warfare, while bronze was cast into ritual bells (dōtaku) and swords.
During the Kofun period, the tatara iron-making method spread. By the Asuka period, Japan’s earliest copper coins, such as Wadōkaichin, were being cast.
In the Nara and Heian periods, religious objects, daily tools, and farming equipment were made with bronze. The Great Buddha of Tōdai-ji—completed in 752—is the world’s largest bronze statue, standing approximately 15 meters tall and weighing 250 tons. Traditional casting methods using stone, soil, and clay molds were employed.
Later, during the Muromachi to Momoyama periods, cast items such as tea ceremony kettles and the Great Buddha of Kamakura were produced.
Edo Period
Development of Ironmaking
In the Edo period, tatara ironmaking was perfected, especially in the Izumo region. The resulting tamahagane steel was prized for making Japanese swords—valued not only as weapons but also as works of art.
Meanwhile, Europe saw the invention of blast furnace ironmaking in 15th-century Germany, leading to a transformation in iron production during the Industrial Revolution.
In Japan, Western military threats in the late Edo period spurred the need for cannons and ships. To support this, reverberatory furnaces were introduced. The Nirayama Reverberatory Furnace, used to cast actual cannons, is now a World Heritage site as the only surviving example in Japan.
The shogunate also adopted cupola furnace technology from the Netherlands—a system still used in modern foundries. Heavy industries like shipbuilding and steelmaking rapidly developed from the Meiji to Taishō eras, becoming key national industries.
Post-WWII
Modern Cast Iron Development
The discovery of ductile cast iron (spheroidal graphite iron) in the UK in 1947 enabled high-strength casting. Postwar Japan prioritized coal and steel production, resulting in a surge in casting output during the 1950s and 60s.
Japanese foundries adapted and advanced foreign techniques, establishing world-class casting capabilities.
The rise of motorization in the 1960s drove the automotive industry, with approximately 60% of cast products used in car components—accounting for around 40% of a vehicle’s weight. However, the bursting of the economic bubble and the globalization of the auto industry led to a shift from mass production to high-mix, low-volume manufacturing.
21st Century
The Casting Industry Today
In the 21st century, Japan’s casting industry continues to evolve. New technologies are being explored to meet demands for lighter products and lower carbon emissions. Innovation in manufacturing processes supports sustainable development and future growth.