Analyses and Preventation of Scabbing Defect Formation on Cast Irons by Casting Simulation

Abstract

In this study, the types and possible causes of the dart defect, which is one of the surface defects that are frequently encountered in foundries, has been examined. As a case, a gearbox part with a high scrap rate of dart defect is considered. First of all, the parameters (mechanical properties of the mold sand, casting temperature, etc.) that are effective in the formation of the dart defect have been checked. According to the outputs of the Magmasoft © Simulation software, in order to prevent the cause of the dart defect in the part made of EN-GJL 300 material, it was observed that the runner ingates did not work in balance as a result of faulty in runner design. The gating system was redesigned with the basic approaches of fluid mechanics, and with the simulation made before the application on pattern, a significant improvement was observed compared to the outputs of the first simulation study. It has been seen that the root cause of the dart defect, which is generally known as sand expansion and the solution of which is sought in the sand parameters, may also be caused by the runner system. By evaluating the general literature and process control results with the simulation software result outputs, the cause of the dart defect was determined and the scrap rate of the part has been reduced by eliminating this defect type.