Improvement of Gating Systems with the Purpose of Reducing Defects in Large-Size Castings from Gray Iron

Abstract

The article analyzes the types of castings defects. There are four groups of them: fit; conditionally fit, with small deviations from the established requirements; correctable marriage; incorrigible or final defects. The way to eliminate casting defects was to change the gating system. Despite the very large number of constructive types of gating systems, 4 classes are distinguished, differing by elements, as well as by hydraulic features of functioning. The article presents the technology of casting processes modeling. In this work the casting process modeling program LVMFlow was used. The LVMFlow system is used for computer modeling of processes that occur in the mold and for optimization of the casting manufacturing technological process. The core of the computer simulation of thermal and hydrodynamic casting processes of LVMFlow are the heat and mass transfer equations. Computer simulation allowed us to trace all the processes that occur in the metal during the filling of the mold, solidification and the occurrence of shrinkage defects. The results of modeling of the initial version of the gating system are presented. The defects such as shrinkage and erosion of the mold, the reject on which was 20%, are found. When the proposed gating system of the siphon type was used, defects for shrinkage and erosion were absent for six months of the production of castings of this type.