Large castings solution casting shrinkage defects, the most fundamental is the focus of the heat balance method is: 1, in the thick of the hot section of the machine tool castings and structure formation, the implementation of rapid solidification, artificially temperature field throughout the casting machine basic balance inside and outside the cold iron, the local use of heat storage capacity of zircon sand, chromite sand or special coatings. 2. Reasonable runner process design within a relatively po casting machine wall, so many and dispersed into the thick of the earliest hours of the first to solidification of liquid metal, solidified thin wall, so the basic equilibrium solidification around for wall thick uniform casting machine, using multiple outlet hole inside runner and the runner more dispersed and uniform, so that the overall heat balance of the fine pores and more, that was underway unobstructed exhaust cooling effect. 3, 4 in the changing position of the runner, the choice of heat storage capacity of the molding material, which is the production of anti-wear products with the EPC is extremely important, chromite sand quartz sand to replace the heat build small sand other species, will achieve good effect, pouring Bi microseismic better. 5, low temperature fast firing, open casting system allows the liquid metal fast, smooth and balanced it to be full of mold pieces of the system should result. 6, machine mold strength ductile iron, surface hardness of ≧ 90, sand box rigidity, favorable to eliminate shrinkage. 7, if necessary riser, when the first move heat riser, and leave the hot section of the riser If placed on the hot section, will increase the size of riser formed on heating hot fix, not only difficult except shrinkage, will produce concentrated shrinkage, but also reduces the process yield.