Founded in 2002, Shandong Zhiheng Vibration Damping Tech. Co., Ltd.(formerly Shandong Ningjin Spring Co., Ltd.) is an assigned manufacturer by the Chinese Ministry of Railways. The production code is DNJ. We specialize in all kinds of cold and hot coiled springs with diameter ranging from 0.1mm to 90mm, especially railway, engineering and mine mechanism and vehicle springs. Our main products include compression springs, extension springs, heavy duty extension springs, precise extension springs, power springs, heavy duty torsion springs, precise torsion springs, and wire formed and metal stamped products.In order to meet the requirements of all customers, Ningjin Spring has established 4 new standard automatic spring production lines. Our spring molding uses intermediate frequency influence heating furnace, and heat treatment uses resistance furnace which are controlled by computers. Now we have 12 sets of various kinds of electric furnaces, 6 automatic spring coiling machines, 4 shot blasting machines, 6 spring testers and a set of spring electrostatic spraying and japanning drying equipment. We own all kinds of production facilities and testing apparatus.To attain most perfect quality, Ningjin Spring passed ISO9001 quality assurance system in 2002. The goods we offered to customers have been warmly welcomed and appreciated for their high quality. It is our only tenet to meet your requirements and give you satisfied goods and services.