ALJ Advantage
RPM Process
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ALJ Advantages
The following are illustrations of the comparisons for an average design between the Rubber Plaster Mold (RPM) process, "hog-outs", sand, permanent mold, investment and die castings.

Tooling Cost - 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.  
Unit 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.
Accuracy - 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.
Surface Finish - Unlike processes using porting agents and coarse grain media, the Rubber Plaster Mold technique guarantees surface finishes that are compatible with painting and oxidizing without additional surface finishing.  
Fine Detail - The use of very fine grain plaster in the Rubber Plaster Mold process allows for the faithful reproduction of minute detail such as cast part numbers, nomenclature and customer's logotypes. Highlight buffing can bring out a bright, natural finish.

Note: Just as every design does not lend itself ideally to any one process, the comparison does not apply in every circumstance.

Rubber Plaster Mold castings reduce time from prototype to production
Other casting processes require long lead times for production dies and create large time gaps from prototype to full production. This gap is greatly reduced with Rubber Plaster Mold castings from the Original prototype tooling.

No Additional Tooling Costs
Paying for expensive dies up front (even though amortized over the life of a product's expected life) drains cash and risks financial set-backs. Instead, the use of Rubber Plaster Mold castings requires no additional tooling costs and keeps cash flow in balance with current production requirements.

RPM reduces risk of new product production
In many instances, industrial companies find themselves in the situation where the market potential for their products is not sufficient to warrant the cost of expensive molds or die tooling, yet they require the advantages of castings, such as shielding, heat dissipation, strength, style, cast lettering, etc. Year in and year out they rely on Rubber Plaster Mold (RPM) and A. L. Johnson Company for their casting requirements.