Abstract
The present paper is a study on the relationship of green sand mold properties such as tensile strength and springback in high pressure molding to grain size distribution of base sand and considers some aspects of grain size distribution in high pressure molding. The following results were obtained on compaction by squeezing at 7kg/cm2 or adding simultaneous jolting; 1) green tensile strength in 4 screen sand was higher than in 1 screen sand, 2) springback in 1 screen sand was smaller than in 4 screen sand, 3) green permeability in 1 screen sand was higher than in 4 screen sand, 4) no conclusion was obtained on comparison of density uniformity, because there was a great difference depending on the ratio of moisture to bentonite. The following results were obtained on compaction by squeezing at pressure beyond 10kg/cm2 ; 1) it could not be concluded whether 4 screen sand or 1 screen sand was higher in green strength because approximately the same maximum strength was indicated within a certain squeeze pressure, 2) springback in 4 screen sand was somewhat lower than in 1 screen sand, and springback at 10kg/cm2 in 4 screen sand was lower than at 7kg/cm2, 3) permeability in 1 screen sand was always higher than in 4 screen sand, 4) density uniformity in 4 screen sand changed a little with compactability, but it in 1 screen sand lowered remarkably with increasing compactability and rose remarkably with decreasing compactability.
