Removal of CrMo alloy steel components from investment casting gating system using vibration-excited fatigue failure.

In investment casting, the separation of cast components composed of strong, hard materials from the gating system is a delicate operation, which can incur considerable costs in terms of labor and tools. In this study, we substituted conventional grinder cutting with vibration-induced fatigue failure to facilitate the separation of chromium-molybdenum (CrMo) alloy steel components from an investment casting tree. This process involves the creation of V-shape notches on the ingate structure as well as modifications to component layout within the pattern tree. Vibration-excited dynamic experiments were performed to examine the effects of notch designs on stress concentration and cutting off at the ingates. Mold flow analysis was used to optimize the design of the pouring system to ensure casts of high quality. Finite element method (FEM) and experimental modal analysis (EMA) were conducted to predict the efficacy of the model and vibration characteristics. The application of harmonic response analysis to a casting tree model determined the maximum and minimum principal stresses at ingate notches. Once the stress values at the ingate notches were sufficient to ensure failure conditions, the same parameters were used to perform a final experiment for verification. Experiment results revealed that the breaks indeed occurred at the notches of the ingate. The proposed approach could be used as an alternative to conventional cutting using a grinding wheel as a means of reducing labor costs, increasing safety, and enhancing production efficiency. [ABSTRACT FROM AUTHOR]