GC International is a highly-skilled, precision CNC machine shop and foundry that produces precision aluminum and zinc parts by machining or casting using a Rubber/Plaster Mold (RPM) process, including complete finishing operations. The company produces parts from a few ounces up to twenty pounds with tolerances of +/- .010″ with quick turnaround, low-cost tooling, no draft, thin wall, smooth surface, quality, and good “machine-ability” castings.
A.L. Johnson, one of the company’s founders, as a worker in the pottery industry, developed the Rubber Plaster Mold process in 1954 while making molds for slip casting, a method used to produce pottery. After leasing a building to Winslow Manufacturing, a machine shop that produced nut plate drills (for aerospace applications), Johnson was contacted by one of the Winslow employees to learn how to cast the drills instead of machining them.
Johnson consolidated several plaster casting processes from other firms and partnered with a gypsum company to develop an aerating plaster that could be used as a mold material. The use of this material in metal casting applications would not require vacuum assistance and would offer customers near-net-shape castings that can be produced in less than two weeks. Johnson’s RPM process was born.
In 1958, Johnson moved the company from Arcadia to Monrovia, California, and in 1968 sold the company. The new manager, as part of GC (Griffith & Carlson) International, Camarillo, California, co-purchased the casting firm in 1975.
In 1991, GC International moved to its present 45,000 sq. ft. facility, where it brought together the RPM tooling and casting line and CNC machining capabilities. Since then, the company has served new markets and increased the use of rapid prototype patterns to accelerate lead times and improve production.