Our process begins by selecting from a variety of iron blends to meet each casting’s unique specification.
Large furnaces melt the iron and stay at temperatures ranging 2,600 to 2,800 degrees Fahrenheit. Computerized systems constantly monitor temperature.
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 shakeout process in which the molds are shaken off and the sand is recycled for reuse. When castings get below about 140 degrees, they are cleaned and finished.
Melting Iron the Waupaca Way
It all starts with turning up the heat. Iron is melted using one of two methods: a cupola, which is a cylindrical shaft furnace; or 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 Fahrenheit. The custom mix of materials in the cupola includes pig iron, recycled iron from our production process, scrap iron, and new metals as specified. By varying the percentage and mix 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.
Our foundry in
Marinette, WI, has electric melt furnaces, which use the magnetic properties of iron to create friction and heat. These furnaces also 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 iron 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.