A hydraulics-based/optimization methodology for gating design

Abstract

Advantages and disadvantages of the differential momentum balance and macroscopic control volume approaches to the analysis of flow during mold filling and the computer-aided design of gating systems are discussed. A gating design methodology based on a control volume hydraulics-based flow model and nonlinear optimization is described. Mathematical formulation of the model yields a system of equations that ensures mass continuity at nodes and conservation of energy along paths. In addition to computational efficiency, the hydraulics approach to flow analysis utilizes a pipe-node-path representation of gating systems that facilitates the analysis of complex three-dimensional configurations. Example simulations of flow distribution in water modeling systems and of flow distribution and mold filling in molten metal experiments are presented. It is concluded that good agreement between model-predicted and experimental results is obtainable if pertinent loss coefficient data are available. However, application of the hydraulics-based methodology to accurate analysis of flow in gating systems requires knowledge of loss coefficients that specifically relate to the flow conditions and types of runner/ingate geometric configurations encountered in industrial castings. An example formulation illustrating the application of nonlinear optimization to gating design is presented.