Crack casting defect is the biggest obstacle restricting the popularization and application of furan resin sand process in steel castings. Professional scholars and experts in the industry have thought of many ways to solve the crack problem, but the effect is not satisfactory. Qiqihar Vehicle Co., Ltd. has strong casting strength and has the furan resin sand production line with the largest production capacity in China, but it also abandoned the resin sand process because it can not solve the crack problem. ZHY Casting also faces the same problem. There are many cracks in the production of cast steel bolster, side frame and motor shell by furan resin sand process, which can not be fundamentally solved. It is very necessary to find a new process to replace furan resin sand process to produce motor shell.
| Process type | Furan resin sand | Alkaline phenolic resin sand |
| Advantage | 1.High strength at room temperature, good collapsibility, good fluidity and high modeling efficiency. 2.The mold and sand core do not need to be dried, which improves the production efficiency and site utilization and shortens the production cycle. 3.The surface of the casting is smooth and clean, and the dimensional accuracy is high and stable. 4.Good compactness of castings. | 1.The curing agent and binder do not contain nitrogen, sulfur, phosphorus and other elements harmful to the casting, eliminating the casting defects caused by sulfur, phosphorus and nitrogen infiltration on the casting surface 2.The mold lifting performance is good, the molding sand is not easy to adhere to the mold, the sand surface is relatively smooth, and the mold lifting slope on the pattern can also be small. 3.Secondary curing at high temperature produces high thermal strength. 4.The explosion thermal expansion is very small and the high-temperature concession is good, which can greatly reduce the thermal crack and hairy wing defects of castings. 5.The sand mold has good collapsibility, smooth casting surface, high and stable dimensional accuracy and high compactness. 6.Little environmental pollution and human injury. |
| Disadvantage | 1.Poor heat dissipation, large thermal expansion and poor concession. 2.Serious sulfurization. 3.There is a very irritating smell in the production process, which is very harmful to the environment and human body. | 1.The normal temperature strength of the binder is low, the amount of binder is too large, and the cost of core making is too high. 2.The old sand is difficult to regenerate and the recovery rate is low. |
By comparing the advantages and disadvantages of the two sand molding processes, it can be seen that alkaline phenolic resin sand not only has the advantages of furan resin sand, but also has high-temperature secondary hardening reaction, improves the thermal strength of sand mold, and effectively prevents sand inclusion, meat and other defects caused by sand mold fracture and collapse. What is more valuable is that it overcomes the disadvantages of poor concession, serious sulfur infiltration and great harm to the environment and human body of furan resin sand, and is very beneficial to solve the crack casting defects of motor shell.