Explanation
gypsum is used to make mold for casting. Use hemihydrate calcium sulfate (basanite) as molding materials. Pour its slurry around the pattern, and lift the mold after hardening=heat and dry the mold, and then casting the metal. Non ferrous metals (such as Au, Ag, Al, Cu) and their alloy with low melting point are commonly used for casting. 3 The advantages of the castings are high dimensional accuracy, smooth surface, and clear contour lines. The disadvantages of pure gypsum mold are low strength, poor air permeability, and large thermal expansion coefficient. Therefore, asbestos, talc, clay, quartz sand, and basanite are usually mixed together to make slurry. In order to increase the air permeability of mold, some active agents are sometimes added to form foam. The disadvantages of plaster mold casting are high cost, many and long processes, and molding materials can not be reused.
Classification
No classification at present.