We start by using a variety of iron blends to meet each customer’s unique requirements.
Iron is melted in large furnaces and stays at temperatures ranging 2,600 to 2,800 degrees Fahrenheit and temperature is constantly monitored by computerized systems.
As the iron travels down the molding line, the temperature gradually decreases from about 2,600 to 1,200 degrees. As the castings cool, they enter a shake out process in which the molds are shaken off the castings and the sand is recycled for reuse. When castings get below about 140 degrees, they can be cleaned and ground.
How Iron is made the ThyssenKrupp Waupaca way
It all starts with turning up the heat. Iron is made in two processes: a cupola, which is a cylindrical shaft furnace; and in an electric melt furnace.
All but one of our foundries uses a cupola to melt iron, which pushes air at supersonic speeds into a base fuel of coke to drive temperatures up to 2,800 degrees F. The custom mix of materials in the cupola includes pig iron, recycled iron from our production process, scrap iron and metals specified by our customers. By varying the percentage of these materials, we change the chemistry of the finished iron. As the iron melts, it trickles through the coke and continues to our holding furnaces.
Only our
foundry in Marinette, WI., has electric melt furnaces to melt iron, which uses the magnetic properties of iron to create friction and ultimately heat. These furnaces are also used to store liquid iron.
Why doesn’t the inside of the cupola melt?
Our cupola shells are cooled externally with water and lined in the melting zone with refractory materials. The cupola will melt for up to 12 days, then we open clamshell doors and drop the ash and unused coke out, expose the inner section, then inspect and repair areas if needed.