Casting process

　　lost foam castingA variety of casting materials are used, of which the important ones are the model material, the casting paint and the dry sand.

　　lost foam castingModel materials are usually called beads, and cast beads are generally divided into PS-polystyrene beads and PMMA-polymethyl methacrylate beads, both of which belong to high molecular materials, and PS PMMA polymers. For plain mild steel castings,lost foam castingThe carbon in the model material can easily cause the surface of the production casting to require carburizing, resulting in various carbon defects. The effects of polystyrene (containing 92% carbon), polystyrene-polymethyl methacrylate copolymer and polymethyl methacrylate (containing 60% carbon) on the carburization of castings decreased in turn. In addition, the important control parameter of gas generation is the density of the model. The gas of the three different materials and the amount of gas generated from small to large are PS, PS PMMA copolymer and PMMA. At the same time, the size of the beads should be selected according to the wall thickness of the casting produced. In order to facilitate the retention of more than three beads in the thinner part of the casting, fine-grained beads should be selected for thin castings and coarse-grained beads should be selected for thick castings.

Dry sand islost foam castingof modeling materials. Due to the characteristics of the process, the choice of dry sand should be related to the casting material. The high temperature alloy is made of dry sand with strong fire resistance and large particles. At present, the dry sand mainly uses natural quartz sand. The iron slag, dust and moisture in the sand should be removed, and the use temperature should be kept below 50.

Coatings arelost foam castingThe essential raw materials for the production line, its main function is to improve the strength and rigidity of the mold, prevent damage or deformation, separate the molten metal from the mold, eliminate the gasification products of the mold, and ensure the surface quality of the casting. Many foundries now use homemade pigments.lost foam castingThe refractory aggregate in the coating mainly includes zircon powder, bauxite, brown corundum powder, quartz powder, talc powder, mullite powder, mica powder, etc. The particle size distribution should take into account the anti-sticking sand and high temperature penetration, and the particle shape is conducive to improving the permeability. Generally, a certain number of spherical particles are selected to facilitate the escape of gas after gasification or the elimination of liquefied products after incomplete decomposition of the model.