We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Cupola Furnace?

By Jeremy Laukkonen
Updated May 17, 2024
Our promise to you
About Mechanics is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At About Mechanics, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A cupola furnace is a cylindrical device that is used to heat and melt metals such as iron and bronze. These blast furnaces are typically between 1.5 and 13 feet (about 0.5 to four meters) in diameter, and have the outward appearance of a smokestack. In order to operate a cupola furnace, the cylinder is usually filled with alternating layers metal and coke, and flux materials, such as lime or carbon adjuncts, can also be added. When the metal melts, it flows down and can be released from a tap on the front of the furnace. After the run is complete, these furnaces can be emptied and prepared for future use by opening a dump gate on the bottom to remove remaining coke and other materials.

Archaeological evidence suggests that cupola designs may have been used in China during the third century BCE. Early examples of cupola furnaces were used in China during the Chunqiu period to cast bronze. Cupola furnaces were also used for cast iron in Europe from the 17th century on. Until the middle of the 20th century, the cupola furnace remained the primary method of casting iron. Most foundries eventually switched over to induction furnaces, though cupolas are still used in some instances.

When a cupola furnace is in use, it is typically referred to as a campaign. At the start of a campaign, coke is placed into the furnace and then ignited. Ports called tuyeres are used to introduce air to the burning coke, which creates a type of blast furnace. The introduction of air to the coke results in it becoming very hot, at which point metal can be set into the furnace. Additional layers of coke are added so that the heating process will continue, and lime or other fluxing agents can be added to reduce oxidation.

Heat from the lower layers of burning coke typically rises through the cylinder, heating the upper layers of metal and melting them. Carbon from the coke can bond with the liquid metal as it runs through the lower layers and pools at the bottom. In some cases, adjuncts such as silicon carbide may be added to increase carbon content. After enough molten metal has pooled in the bottom part of a cupola furnace, the operator can open a spigot to drain it into a collection vessel. There is typically another spigot at a higher point on the back of the device that can drain slag materials.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.