The mathematical model and numerical simulations of the solidification of a cylindrical shaped casting, which take into account the process of filling the mould cavity by liquid metal and feeding the casting through the riser during its solidification, are presented in the paper. Mutual dependence of thermal and flow phenomena were taken into account because have an essential influence on solidification process. The effect of the riser shape on the effectiveness of feeding of the solidifying casting was determined. In order to obtain the casting without shrinkage defects, an appropriate selection of riser shape was made, which is important for foundry practice. Numerical calculations of the solidification process of system consisting of the casting and the conical or cylindrical riser were carried out. The velocity fields have been obtained from the solution of momentum equations and continuity equation, while temperature fields from solving the equation of heat conductivity containing the convection term. Changes in thermo-physical parameters as a function of temperature were considered. The finite element method (FEM) was used to solve the problem.
The paper includes validation studies of the flow module of the NovaFlow&Solid simulation code. Experiments of ductile iron and gray iron casting in a spiral test of castability were carried out. Casting experiments were then carried out in industrial conditions in the Ferrex Foundry in Poznań and the results are the castability spiral length and local cast iron rate during mould cavity pouring. Simulation tests using NovaFlow&Solid Control Volume code were made. The technological castability test was used to determine thermal-physical data through simplified inversion problem. Influence of physical parameters in the database of simulation code on the spiral length obtained as the result of simulation was analyzed. It was found that critical fraction of capillary flow CLFdown has the biggest impact on cast iron castability in the simulation code. The simulations resulted in defining parameters of gray iron GJL 250 and ductile iron GJS-400-15. For the parameters set, the length of castability spiral in simulations was in accordance with casting experiments.
Energy conservation is an important step to overcome the energy crisis and prevent environmental pollution. Casting industry is a major consumer of energy among all the industries. The distribution of electrical energy consumed in all the departments of the foundry is presented. Nearly 70% of the energy is consumed especially in the melting department alone. Production of casting involves number of process variables. Even though lot of efforts has been taken to prevent defects, it occurs in the casting due to variables present in the process. This paper focuses the energy saving by improving the casting yield and by reducing the rejections. Furthermore an analysis is made on power consumption for melting in the induction furnace to produce defective castings and improvement in the casting yield. The energy consumed to produce defective castings in all other departments is also presented. This analysis reveals that without any further investment in the foundry, it is possible to save 3248.15 kWh of energy by reducing the rejections as well as by improving the casting yield. The redesign of the feeding system and the reduced major rejection shrinkage in the body casting improved the casting yield from 56% to 72% and also the effective yield from 12.89% to 66.80%.