Approximately half of our business consists of pouring permanent mold castings. The molds are made of cast iron, steel and H-13 tool steel or a combination of these metals. The up-front higher cost of tooling helps to keep the piece price down and the length of service up.
Most of our long running production jobs are made this way including much of the military munitions parts (JDAM) and high production commercial aircraft parts (Boeing 737). Smoother surface finishes are generally obtained along with less process variation resulting in a more reliably sound casting.
Many of the parts we produce in permanent mold require a high tensile strength (40ksi tensile, 50ksi ultimate and 3.5% elongation). Often, a casting is pulled from each heat treat lot, cut and tensile tested. Some parts have a 4 inch or more thick section which require manual or automated mold cooling techniques.
We frequently use our state of the art Digital Valve Systems Inc. automated timing, misting and cooling machines attached to specially made ports on the molds to keep the temperatures in control.
Most of our permanent mold castings are made with a shell core for a smooth interior finish, superior gas venting and ease of core removal. Shell cores are the best choice for extended production jobs due to tooling durability and high daily production rates.