Okhuysen, Victor F and Voigt, Robert C

Abstract: While it has been long known that changes in geometry result in changes in shrink rules (tooling allowances), a robust predictive model has remained elusive. A new geometric description is proposed based on mold/die restraint on the casting/wax pattern. This new restraint based geometric description is introduced with a qualitative approach, as well as two different quantitative approaches. These restraint models were then tested with a database of over 300 different features and other casting descriptors. The analysis indicates that the restraint based descriptions hold merit, and with further improvements may be excellent tools on the descriptions of the effects of geometry on tooling allowances. A brief set of recommendations is given as to how foundries can apply these guidelines to improve their own tooling allowance (shrink rule) assignment practice.