At present, the main domestic manufacturers of nodular cast iron piston rings for automotive diesel engines, mini cars and motorcycles include Nanjing piston ring factory, Nanping auto parts factory, Fujian east Asia Machinery Co., Ltd Taoyuan Sanli Piston Ring Co., Ltd., Wuxi Mengyuan Casting Co., Ltd., etc. There are three casting processes for nodular cast iron piston rings in these enterprises:
1. Double piece elliptical casting process
This process of German Gertz company is really unique and has good casting process. It has strong adaptability regardless of the large, medium and small diameter of the ring. In the domestic piston ring industry, almost all major manufacturers have adopted the double piece casting process of gerz company.
2. Single elliptical casting process
Only a few manufacturers have adopted this process, which is to produce nodular cast iron piston rings for mini cars and motorcycles with small cylinder diameter. Although the process is relatively simple, it does have its disadvantages, that is, the utilization rate of molten iron is too low, only 10-15%. A large amount of return charge of nodular cast iron piston ring is produced in production, which should be completely digested in the production of alloy ring.
3. Lost foam casting process
At present, only two domestic enterprises producing motorcycle nodular cast iron piston ring blanks in Wuxi have adopted this process. E PC process is relatively simple, but it does have its disadvantages, that is, shrinkage defects will occur in the blank. Although it will not have much impact on the normal use of the accessory ring, it is not a perfect product after all. There are also ways to solve this problem, but the cost is high.
To sum up, China’s nodular cast iron piston rings basically adopt the double piece elliptical casting process introduced from gerz company. Since 1985, through technology introduction, digestion and absorption, and continuous improvement in production, the technology has been very mature, and the product quality can fully meet the standard requirements of gerz company. Monomer and EPC casting processes have only been applied in three companies in the past decade, and may not be popularized in the future. According to the development trend of reducing production cost and improving production efficiency, if the problem of slicing machine tool is solved, the four piece ellipse of gerz company and the elliptical cylinder casting process of Japan should be tried and popularized in the future.