PRECISION CASTING OF IMPELLERS.

IHI has experimentally fabricated a number of impellers with adequate precision and quality by means of such precision casting methods as the lost wax or the plaster mold method. As a result of this experimental fabrication, it was proven that impellers with or without shrouds can be cast from either stainless steel or aluminum alloy, satisfying all the specifications covering mechanical properties, surface and internal qualities, and dimensional accuracy. Described in this paper are the product qualities and part of the working program including pattern making and molding and casting practices. The fabrication of impellers by means of precision casting of this sort is expected to prevail in the future as the size of impellers becomes larger and their design becomes more complex.