What Should Notice When Processing Nodular Cast Iron Manhole Cover? (Part 2)
During the casting process, there are often problems with porosity, which brings a lot of trouble to the processing of the manhole cover. Porosity is the shortcoming of bubbles formed by the separated gas remaining in the ingot during the cooling and condensation of the metal liquid. The Ductile iron manhole covers supplier will analyze the primary cause of the blowhole. 1. The poor air permeability of paint or lack of negative pressure, the poor air permeability of sand filling, can not exhaust the gas and residues in the cavity in time, and form pores under the filling pressure. 2. The pouring speed is too slow to fill the gate cup, expose the sprue, get in the air, and suck in the slag, forming the air hole and slag hole. 3. A large amount of gas and residues generated by the gasification and decomposition of the foam model cannot be discharged out of the mold in time. The dryness of the foam and paint layer filled with dry sand is poor. Surrounded by th...