Gu Chang-year foundry cast iron covers production process: cast iron covers the production process is essential for heat treatment in order to eliminate excess iron in solution components, so as to make the covers to meet the requirements for use. Then the ball is ductile iron manhole covers offer, but added nodulizer time is required, and we must see that the temperature of hot metal composition was also able to meet the process requirements, and then it poured. After casting we get just a cast-iron wood-type, there are some flaws ductile iron manhole covers, this time of need is a full circle and polishing process. In addition, there are treated as well as the packaging process, the covers or other products coated with a layer of asphalt paint pillar on ductile iron manhole covers bearing, and then packaging and storage. Theft of manhole covers methods are there? First, the chain connection method. Second, the hinge joint law. Both methods can not be locked into one Manhole covers and manhole covers Grates, easy to open, that is able to use the drill rod chains, pry off the hinges. Third, only the mouth anti-spin technique method. Just reverse rotation in place, you can open and took the covers. Gu Chang annual production of foundry cast iron covers are the best choice for business and government, not only cheap, but also to ensure product quality, trustworthy. Size of manhole covers, Chang-year foundry (certified), Yangquan ductile iron manhole covers are provided by Gu Chang in foundry. Gu Chang-year foundry (www.sxcnzz.com) is Jinzhong, machining leader, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. Chang-year leadership in the foundry staff warmly welcome all inquiries negotiations to create Chang foundry in a better future.