AFS Library


Journal: AFS TRANSACTIONS (1970), p. 293-296
Author: W.L. Hallerberg

The system of gating sand castings using fluid flow criteria developed by AFS for gray iron has been simplified and reduced to a single equation. The hypothesis that this equation can be used to calculate the gating system for any alloy with the correct choice of X and K was tested by several experiments. A computer program was written to quickly and accurately calculate choke areas from the necessary input. Concurrently, the surface area to volume ratio approach to the risering of stainless steel was investigated. Work of other authors was collected and a graph of riser size (dia equals height) vs surface area and volume was generated using metal shrinkage and mold wall movement data from the literature. Using the AFS gating equation with X=0.279 lb/in. and K=0.4 and the risering graph mentioned above, trials were run in HL-40 stainless steel. Three sizes of high temperature support brackets were successfully cast; one separately, the other 2 back to back from a common gating system. The system was adopted by the production foundry. Pictures and diagrams of the gating systems used and the proper values of fluidity and density, the AFS gating equation for gray iron can be applied to stainless steel with success; riser sizes for stainless castings in green sand can be determined by using a surface area to volume ratio-technique with proper values of total shrinkage during solidification inserted in the defining equation.

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