At the same time, the size of the beads should be selected according to the wall thickness of the castings produced. In general, thicker castings use coarser beads, whereas thinner castings use finer beads to make the casting thinnest It is better to keep more than three beads at the site. In addition, the pre-release and shaping control of model materials is also a key to the technical success. Under normal circumstances, the density of pre-release beads is controlled at about 0.024 ~ 0.03g / cm3, and its volume is about 30 times the volume of the original beads. The density of the forming model is controlled at about 0.02 to 0.025 g / cm3. Dry sand is a molding material for lost foam china Copper Reducing Tee Fittings casting. Due to the characteristics of this process, the choice of dry sand should be related to the material of the casting. The high-temperature alloy uses dry sand with higher refractory and coarser particles.

At present, dry sand mainly uses natural quartz sand. Iron slag, dust and moisture in the sand should be removed, and the use temperature should not be higher than 50 ℃. Paint is an indispensable raw material in lost foam casting. Many foundries now use homemade paint. The main role of the coating is to improve the strength and rigidity of the model, to prevent damage or deformation; to isolate the molten metal and the mold; to exclude the gasification products of the model; to ensure the quality of the casting surface. The refractory aggregates in the lost foam coating mainly include zircon powder, bauxite, brown corundum powder, quartz powder, talc powder, mullite powder, mica powder, etc.

The particle size grading should take into account the prevention of sticky sand and high temperature permeability, and the particle shape is conducive to improving the permeability. Usually, a certain number of spherical particles are selected, which is conducive to the escape of gas after the model gasification or the liquefied product of the model incomplete decomposition exclude. Second, the control of paint preparation Lost foam casting paint carrier mostly use water-based, in order to facilitate environmental protection. Its adhesives mainly include clay, water glass, syrup, pulp waste liquid, white latex, silica sol and so on. In the selection of adhesives, consider the following factors: high temperature gas generation; coating properties; coating strength and stiffness; erosion model properties.