Nan self hard resin sand characteristics: 1.the mold (core) high strength, good collapsibility, can ensure the dimensional accuracy and surface quality of the casting. 2, good mobility, can improve type (core) filling, improve type (core) quality and labor productivity, reduce the labor intensity of workers. 3, save energy, casting (core) only need to bake, to meet the requirements of pouring. 4, the old sand can be recycled, which can further reduce the cost;