The paper presents results of metallographic examination of faults occurring in the course of founding thin-walled cast-iron castings in

furan resin sand molds. A non-conformance of the scab type was Observed on surface of the casting as well as sand buckles and cold

shots. Studied the chemical composition by means of a scanning electron microscope in a region of casting defects: microanalysis point

and microanalysis surface. Around the observed defects discloses high concentration of oxides of iron, manganese and silicon.

A computer simulation of the casting process has been carried out with the objective to establish the cause of occurrence of cold shots on

casting surface. The simulation was carried out with the use of NovaFlow & Solid program. We analyzed the flowing metal in the mold

cavity. The main reason for the occurrence of casting defects on the surface of the casting was gating system, which caused turbulent flow

of metal with a distinctive splash stream of liquid alloy.