Bidwell H T

Abstract: This article provides some general tolerance guidelines for designing features into investment cast components. In investment casting, tolerances may be affected by a number of variables, including wax temperature, injection pressure for the wax, die temperature, shell composition and position of the component on the casting tree. As a rule, linear tolerances on investment castings are 1770.01 in. with dimensions up to 1 inch., and ?1770.003 in./in. for each additional inch up to 10 in. Other tolerancing information in the article includes flatness, concentricity, parallelism angularity and perpendicularity. One important characteristic of investment castings is the ability to produce a smooth surface. Surface texture standards are 125 RMS max and 115 AA max.

Keywords:designing, Investment casting, Tolerances, Surface texture.