Production of a Heavy Section Ductile Iron Grinding Table

Abstract

Production process of an extra-large ductile iron grinding table with weight of 142 t was introduced in the present paper. Solidification process of the grinding table was simulated with finite element software ProCAST. Defects, especially porosity, of the casting during solidification were predicted and hence casting process optimization has been performed based on the simulation results. In manufacturing period of the ductile iron grinding table, the following measures were adopted to avoid casting defects and improve its mechanical properties. Firstly, bottom-gated gating system was used. Secondly, chills were set on the heavy section locations. Thirdly, risers were set on the top of the casting. Besides, chemical composition was strictly controlled and raw materials with fewer impurities were used. More than 150 t molten melt was supplied using medium frequency induction furnaces. Cored wire injection nodularizing and inoculation was performed at 1360～1380℃ by two ladles with capacity of 75 t. Post–inoculation was conducted during pouring as well as low temperature and fast pouring process was adopted. The qualified heavy section ductile iron grinding table product can thus be obtained. Shrinkage and porosity was evidently decreased at thermal center of the casting. The result of casting inspection showed that mechanical properties of the casting met the requirements of EN-GJS-400-15U grade nodular iron and the UT detection didn't find any casting defect exceeding grade 3 according to EN 12680-3-2003.