A Look at Our Mapleton Foundry

For more than 85 years, Caterpillar engines have been powering the industries and businesses that communities around the world rely on to meet critical needs: hospitals, airports and data centers; marine vessels and locomotives; and of course, the heavy equipment digging, dozing, hauling and dumping at our customers’ worksites every day.

Caterpillar engines have earned their reputation for world-class strength and durability. The Caterpillar Foundry in Mapleton, Illinois, is where that reputation begins. 

More than 800 employees at the Mapleton plant make the cast iron blocks at the heart of most of the company’s engine platforms. It’s hard work that demands a focus on safety, quality and commitment to helping customers build a better world. Mapleton employees are a special kind of maker – executing an art that has been practiced for more than 1000 years to transform sand and metals into a solid block of iron.  

About Mapleton

The Mapleton Foundry is one of the largest in the United States. It can melt up to 1,000 tons of iron each day to produce finished castings ranging from 15lb liners to 22,000lb cylinder blocks. These components are the foundation for the company’s 115-6,600hp (86- 4,920 kW) engine platforms. The facility ships an average of 150,000 tons of finished product each year.  


Sand, scrap and molten iron! Watch this video to see the process employees at Mapleton use to make an engine block.

process employees at Mapleton use to make an engine block

Did you know?

  • All melting at the Caterpillar Foundry in Mapleton is done in low 65-ton (59 metric ton) induction furnaces, a 30-ton (27 metric ton) medium frequency induction batching furnace (the largest of its type in the industry), and one 24-ton (22 metric ton) arc furnace.
  • Up to 500 tons of sand are trucked into the Mapleton facility each day. Sand cores are used to form cavities in our complex castings.  It takes 1,200 pounds of sand to create an engine block core for a Cat 3500 engine, and up to 10 cores to make one complete block mold.
  • Mapleton is home to the largest core making machine in the world.
  • The largest block ever built at the facility had a sand mold that weighed 60,000 pounds (4X the weight of an elephant).
  • The automated Loramendi core making equipment used for high-volume castings has received an Illinois Governor's Pollution Prevention Award for its positive impact on the environment.
  • Mapleton's modern blasting technology (three programmable, rotary shot-blasts and an automated liner blast) ensures the best internal cleanliness possible. Heads and blocks can be stress-relieved in one of the six furnaces.
  • Our in-house pattern shop is responsible for making and maintaining the patterns and equipment used to make molds and cores. The pattern shop is also involved in design and development of new castings.
  • The Mapleton facility houses a metallurgical lab to test chemical composition and facilitate microstructural analysis.  Casting mechanical properties (including tensile strength, elongation, and hardness) are audited according to customer specifications.
  • Quality assurance capabilities include X-Ray, Magna Flux, ultrasonic, chalk and oil, boroscopes, Infinity/SPC software, and casting traceability.
  • Layout capabilities include a coordinate measuring machine capable of measuring castings up to 9 feet tall and 18 feet in length.
  • Environmental compliance is a multi-million-dollar annual operation at the foundry, including a state-of-the-art wastewater treatment plant, air pollution control equipment, on-site sand disposal and several recycling programs.