Elimination of casting defects induced by cold box cores

Abstract

One of the challenges of foundry industries is rejection of casting caused by porosity defects. Of the many factors, proper selection of core manufacturing process has higher impact on the reduction of porosity defects in castings. Cold box core making processes widely used by foundry industries to produce cores because of its good productivity and ability to produce complex designed cores. However, the probability of porosity defect in castings produced using cold box cores is higher than that of other processes. Globally, research is being carried out to solve the porosity defects in castings. However, complexity of the process and involvement of more process variables necessitate identification of root causes of the defects. This work aims at resolving the porosity defect in castings, when cold box core is used. Cores produced by furan core making process, which rarely results in porosity defects, was set as standard for testing the effectiveness of cores produced by cold box core making process. The results indicate that considerably high nitrogen content in the charge raw material in secondary iron making foundries enables reaction of metal with core (binder). Consequently, porosity arises in castings. The remedial measures to control the nitrogen content ensured casting rejections less than 7% in the foundry.