This paper and the presentation will cover the actual foundry trials and the differences observed in wax versus FOPAT with respect to cost, productivity and enhanced capabilities.
As part of the Department of Defense’s SBIR (Small Business Innovative Research) program, FOPAT Production Inc. of Dayton, Ohio partnered with several investment casting foundries to demonstrate FOPAT’s effectiveness as an alternative pattern material to wax. Foundry trials were conducted to demonstrate effectiveness in reducing rework or scrap costs, improving dimensional accuracy, and enhancing the foundry’s competitiveness and capabilities to do difficult parts (with respect to thin sections, cored parts, etc.) Some of the advantages of FOPAT over wax include: temperature stability up to 250F (eliminating need for air conditioned wax room), more durable especially for thin sections, easy to handle and assemble, and a longer shelf life. Since FOPAT is injected at a very low pressure, it was demonstrated that there was significantly less core breakage than during wax injection. FOPAT patterns do not exhibit the creep properties of wax, so no fixturing is necessary and patterns can be shipped same day.
Each foundry selected a part with a history of wax quality issues, either dimensional deviations, expansion problems, or core breakage. FOPAT tools were designed and built from CAD files, then injected with a proprietary formulation of various polymers to produce the foam patterns (FOPAT). Patterns were cleaned and inspected before shipping to the foundries. In some cases the identical part in wax was run simultaneously with the foam so direct comparisons could be made in terms of time spent producing patterns, scrap rates, dimensional stability of patterns, and time spent in assembly. Results are expected to reveal that a variety of quality issues can be improved upon or eliminated through the use of FOPAT in place of wax.