Process of Investment Casting

Milwaukee Precision Casting, Inc. uses the investment casting process to benefit our customers. The investment casting process provides incredible design flexibility, numerous material options, and superior quality. Best of all, investment casting is typically more cost effective than traditional casting methods.

First, high temperature wax is injected into an aluminum molding tool to form a wax impression of the component. It is then removed and multiple patterns are assembled into a tree of parts. Around this wax tree a ceramic shell approximately 3/8” thick is built. The wax is melted out, resulting in a hollow ceramic shell. The ceramic shell is then fired for strength and molten metal is poured into the shell. After the alloy is cooled, the ceramic shell is removed, and castings are cut-off the tree and cleaned and subjected to heat treat if required. Depending on tolerance requirements, some secondary machining may be required for proper function.

Lost Wax Casting Process

Investment Castings are made from the commonly referred to the “lost wax casting process”. Here's how the process works. First, high temperature wax is injected into a ceramic shell mold to form a pattern. The wax is then removed from the mold after it has cooled. The pattern created by the removed wax form now resembles the component. This mold is then heated in a fire oven, and molten metal is poured into the mold. After the metal has cooled and set, the precision castings are cleaned and subjected to further heat treatments. Depending on the specific design requirements, some machining may be performed to bring the castings to their precise final form.

Investment casting is an extremely cost effective and highly accurate process. Also, many high strength and corrosion resistant materials can be used in investment casting, including:

  • Low to high carbon alloy steel
  • Tool steel
  • Stainless steel
  • Nickel base alloys
  • Cobalt base alloys
  • Aluminum alloys
  • Brass alloys

Visit our investment casting benefits page to learn more about the benefits of investment casting.