Core Making: Cold Box, Warm Box & Shell | Waupaca Foundry

Core Making: Cold Box, WARM BOx & shell

Core Making​​: Cold Box, Warm Box & Shell

​The core is a chemically bonded sand shape that creates the interior surfaces of an iron casting. A core box is the tooling used to create the core. High-quality cores are essential to the iron casting process. At Waupaca Foundry, we have the ability to design and manufacture custom core machines. Our machines use three types of core making processes, offering flexibility for both low- and high-volume applications:
  • Isocure™ cold box
  • Warm box
  • Shell

Our robotic technology automates the unloading, coating, and finishing of cores, increasing our volume and efficiency while maintaining quality and cost effectiveness.



The Isocure™ Core-Making Process (Cold Box)

In this process, no heat is applied to the core box and a phenolic urethane resin is added to the sand. A catalyst, in this case amine gas, is introduced into the core box and purged through the core with superheated air. This process is very fast and cost effective for large cores.
Cold box core machines are:

  • Versatile to run vertically or horizontally
  • Flexible and manufactured in sizes that can accommodate up to 150 liters of sand
  • Speedy and allow quick changes
  • Adaptable to move in six directions allowing us to make complicated cores

cold box core making

These diverse capabilities and our innovative processes, result in hard, solid cores to create our consistent high-quality iron castings.


Warm Box Core-Making Process

Waupaca Foundry uses a furan system where furan resin is added to the sand and the catalyst is heat. Cores are baked in a heated box to 450 degrees until the outside of the core hardens; the core continues cooling outside of the hot box. This process is ideal for cores with thin sections because the cores resist breakdown and erosion by molten metal.

Shell Core-Making Process

Sand is pre-coated with a resin and poured into a pre-heated core box. In this case, there is no catalyst and the surface is heated until it forms a thin, hard shell. The sand on the inside of the core is uncured and can actually be poured out and reused. This process is ideal for:

  • Lighter castings where weight is critical
  • Fine dimensional controls that require a fine finish

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