(1) The functions of lost foam casting coatings:
1) Improve the strength and stiffness of foam high ultra fine plastic molds, prevent deformation and damage, and ensure dimensional accuracy.
2) Ensure that the gas generated by thermal decomposition of the foam plastic mold is discharged smoothly during pouring to prevent casting defects in the sand casting.
3) Isolate the molten metal and the molding sand, prevent the molten metal from penetrating into the molding sand, and obtain castings with a smooth surface.
4) Use coatings with different thermal conductivities to control the cooling rate of the molten metal in the mold and improve the fluidity of the molten metal.
(2) Requirements for coatings for lost foam casting:
1) It must have certain strength, stiffness and erosion resistance.
2) It must have good enough air permeability to help the escape of pyrolysis products after the foam plastic mold is gasified.
3) It can be evenly coated on the surface of the foam plastic mold. After the coating is cured, there is no tendency to absorb moisture or reduce the strength.
4) The coating has a certain degree of fire resistance, is not easy to crack, and has strong resistance to the penetration of molten metal.
5) When used, the paint should be odorless, non-toxic and reasonably priced.
Link to this article:The functions and requirements of lost foam casting coatings
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