Main tips affects black malleable iron pipe fittings
The main tips affects black malleable iron pipe fittings performance are moisture content, air permeability, molding sand particle size, wet strength and molding sand temperature.
1.Molding sand particle size, too small size will reduce the strength and plasticity of molding sand, and reduce the air permeability meanwhile
2.moisture content, it required that molding sand need to have a certain plasticity, due to the sand contain some of clay, when the clay meet the water, it got viscoplasticity,so the casting molding sand must have moisture, but should be controlled in a certain range
3.Air permeability, since the molding sand contain water, and will turned into steam when casting, if the sand lack permeability, water vapor and other gases cannot be ruled out timely, will directly lead to problems such as pipe holes.
4.Wet strength. Molding sand must have certain strength to withstand various outside forces
5.Molding sand temperature. Molding sand temperature can not be higher than 40 degree C, the temperature too high will lead to: molding sand strength and permeability change, viscosity increase, outer surface is too dry, reduce the ability to resist sand erosion