Packing mold material used in investment precision casting

Abstract

The invention relates to a packing mold material used in investment precision casting, which comprises starch serving as a packing material, and further comprises petroleum wax, organic superpolymer, rosin and 5 to 20 percent by mass of tapioca. As tapioca is added in the packing mold material, the shrinkage ratio and the expansion ratio of the packing mold material can be controlled effectively, which is very important for controlling casting dimensional precision in investment precision casting. The tapioca is wide in source, and lower in cost than other packing mold materials, and does not react with an investment casting shell. The packing mold material has the advantages that the linear shrinkage ratio and the ash content are low and the strength, the smearing property and the flowability are better, thereby being suitable for manufacturing model wax of large thin-walled investment precision casting and ornamental article casting with higher surface quality requirements.

Description

technical field [0001] The invention relates to a packing mold material for investment precision casting, which is suitable for large-scale thin-walled investment precision castings and jewelry investment precision castings with high requirements on surface quality. Background technique [0002] Investment casting is also called lost wax casting. Its process steps are to use waxy materials to make the shape of the object to be cast, weld the pouring system on the shape to prepare a wax mold, and then cover the wax mold with refractory coating, etc. After the refractory coating is dried and solidified, the mold is demoulded, and the wax mold is completely melted and lost, leaving only the mold shell, and then the molten metal is poured from the sprue, and the refractory coating mold shell is removed after cooling to obtain the required metal casting. [0003] The product of investment casting precision casting is accurate in size, close to the final shape of the part, and can...

AI Technical Summary

Problems solved by technology

[0013] Compared with CN1325566C and CN1103352C, the performance of the mold material announced by Chinese patent CN101074320B has a certain improvement, but generally speaking, the linear shrinkage and ash content of these mold materials are still at a high level, and it is difficult to meet the requirements of precision thin-walled or jewelry castings for dimensional accuracy and surface quality. increasing demands

The mold material has a high strength, which can reach about 20MPa, but the linear shrinkage rate is generally higher than 0.5%, and it is difficult to meet the demand for high-dimensional precision precision castings for the mold material; the starch particle size in the mold material is relatively large, which affects the surface quality of the final product. There are adverse effects; moreover, the starch used as a filler comes from the main food crops of human beings such as corn, wheat and rice, and its application value in actual investment casting is greatly reduced in today's international food shortage

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