A.L. Johnson Company

A. L. Johnson Company, founded in 1954, is a manufacturing/foundry facility which produces precision aluminum and zinc castings using the Rubber/Plaster Mold (RPM) process, including complete machining and finishing operations.A. L. Johnson Company produces parts from ounces to twenty pounds, tolerances plus or minus .010' minimum. We offer quick turnaround, low cost tooling, no draft, thin wall, smooth surface, quality and good 'machine-ability' castings.

Our History
A.L. Johnson, a pottery industry worker, 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 on how to cast the drills instead of machine them. Johnson then 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, Calif., to Monrovia, California, where he sold the company in 1968. The new manager, as part of GC (Griffith &Carlson) International, Camarillo, California, co-purchased the casting firm in 1975. In 1991, A.L. Johnson moved to its present 45,000 sq.-ft. facility, where it brought together an RPM tooling line, casting line and CNC machining capabilities. Since then, the company has tapped into further markets and increased its use of rapid prototype patterns to accelerate lead times and improve production.

ALJ Advantages

Rubber Plaster Mold patterns are SLA, FDM, or machined from stock and tooling can be fabricated without draft as compared with dies machined from tool-steel or iron, always with draft. Unlike other processes, RPM does not require lightening cavities to maintain uniform section thickness, hence less cost. Using the Rubber Plaster Mold process, unit costs can be lower than apparently less expensive methods when considering the combined casting price and finished machining cost. Unit cost, combined with tooling amortization, make it feasible to cast as few as 7 to 10 units with the Rubber Plaster Mold method.Although dimensional tolerances for Rubber Plaster Mold castings are larger than for die castings, often the absence of the need for draft compensates for this condition. Closer tolerances than those listed can often be obtained without additional cost.