Control of Quality in Metal Properties, Dimensional Accuracy, and Surface Finish

The problems encountered in casting grey iron parts with wall thicknesses of 0.125 in. or less are in the areas of controlling the metallurgical structure, the chemical analysis, and varying cooling rates. Special test molds have been designed to determine the structure of grey irons of varying wall thicknesses. Spectrographic chemistry determination techniques are available for fast and accurate determination of all metallic elements when they are in percentages above 0.1%. Equipment is available for determining the cooling curve of grey irons. Changes in structure and chemistry however must be evaluated by use of statistical techniques, using various charts. Dimensional control problems are handled by rules of design. Casting finish problems are controlled by engineering.