NPR’s foundry is located in Iwate, Sendai City, 250km away from Tokyo, in Northeast Japan. It was built in 194. There are 8 production lines and 3 types of molding equipment in the casting workshop of yanhandmade factory. The production process of nodular cast iron piston ring blank is as follows:
1) Double piece elliptical casting process
This technology is imported from German gerz company, including four gerz automatic molding machines and production lines. The production process of nodular cast iron piston ring includes 385x335x20 formwork, 415x365x35 steel plate square sand box and other tooling, which is also completely consistent with that of Gertz company.
2) Casting technology of elliptical short cylinder
This is a nodular cast iron piston ring casting process developed by NPR company, which adopts a sm-50v box free vertical parting molding line of Japan Guangyang Co., Ltd. The sand mold size is 500 x 500 x, the thickness is 100-200 mm, and 10-30 short cylinder ring molds can be arranged in each box. The production efficiency of the molding line is very high. The molding can reach 500 ductile iron piston rings per hour. The cylinder diameter of piston rings is mainly 50-140 mm. Because of the high production efficiency, many slicing machines are needed for slicing. At present, there are 14 special automatic slicing machines in the rock handicraft factory, which are developed by NPR company because of their huge volume and complex structure.