Ductile iron manhole covers have high strength and good toughness, so they are about 30% lighter than gray cast iron manhole covers of the same type. Nodular cast iron brand qt500-7, hot iron temperature is not lower than 1456℃, in the spheroidizing treatment with rare earth ferrosilicon magnesium alloy
1. In order to ensure the basic strength requirements, it is necessary to install the cement foundation with ductile iron grate before; Ductile iron Grating.
The surface of the type (core) is loose; The pressure of the core is too high or too low; The exhaust of the mold is not smooth; The mold runs sand due to the large gap of the box surface;
Mechanical design engineers should know that pressure casting (referred to as die casting) is a kind of casting.