In 2012, the foundry of VÍTKOVICE Heavy Machinery a.s. produced the heaviest steel casting in its history, which was successfully shipped to the customer this spring. The project involved a large steel frame (6.49 x 6.49 x 2 m, GS 20Mn5) for a high-speed forging machine.
The steel frame‘s gross weight was an astonishing 380 tons. Just the production of a wooden model in the pattern shop took more than 1600 man-hours of labor. The sand mold was made from furan-bonded silica and chromite sand. Various protective and insulating coatings were applied on the mold surface. Sand and coating types were selected based on experience and subsequently validated by MAGMA5. Among other aspects, the simulations assessed the thermal impact inside the casting and the mold during solidification, including sand burn-on or penetration of metal into the sand mold.
The molding process took approximately 500 hours. Due to the size of the casting, 5 ladles with a total capacity of 280 tons were employed simultaneously during pouring. After a certain time, which was estimated with the help of MAGMA5, filling of open feeders was performed from an additional two ladles (68 tons and 32 tons). It was very important to secure an absolute synchronization, both during the actual production of the molten steel and also during pouring from the five ladles, in order to accomplish the base filling in less than 300 seconds. After this time, the molding material starts to degrade thermally, which may lead to a reduced internal and surface quality and to geometrical inhomogeneity.