Abstract
Castings with as-cast high dimensional accuracy and superior surface quality can be produced by precision casting. There are two methods of precision casting ; one is the investment casting method using lost pattern, e. g. lost wax process, and the other is the ceramic mold casting method, e. g. Shaw process or C. M. process. Our laboratory has been engaged in research to produce products with high added value and complicated shapes. We have especially concentrated on developing the yet unexploited field of large size precision casting and in 1963 we finally succeeded in developing the CM process which is a kind of ceramic mold process. Since then we have made large steam turbine nozzles used for steam power generators, etc. However, the degree of precision inherent to ceramic mold was not quite satisfactory. We then proceeded with our research activity to develop a precision casting method to make castings with higher demensional accuracy. Our all-out efforts have been crowned with success by the development of the DPM process (Disposable Pattern Mold) with which we can produce large size precision castings. Outline of the process is described in this paper.
