Industry news
Analysis and countermeasures of mould casting defects related to mould shell-1
Causes | countermeasures |
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Air bubbles in the top coat | Choose wetting agent with less foaming property, and add sufficient amount of suitable defoamer at the same time. When preparing the paint slurry, there should be long enough time in the L-shaped mixer stirring slowly, so that the air bubbles float and escape. |
Poor wetting of wax moulds with paint | Careful cleaning of the wax moulds with a good quality mould cleaner. Add a good wetting agent to the topcoat and increase the dosage appropriately. |
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High viscosity of paint slurry | Appropriate reduction of viscosity Pre-impregnation of modules with pre-impregnation solution before top coating |
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Improper slurry handling | Modules are slowly immersed in the paint slurry in the proper direction to avoid holding air. Carefully observe for air bubbles, especially in corners and recesses, before the top layer is sanded. If there are, try to remove them with air nozzle or brush. The top layer of paint is impregnated and coated by 1~3 times Vacuum degassing or vacuum dipping of the paint slurry if necessary. |
Irregular operation of empty material | When empty, rotate the module in different directions to remove air bubbles. |
Causes | countermeasures |
Poor wettability between paint and wax mould, selective adsorption after sanding | Thorough cleaning of wax moulds with high-quality cleaning agents Moderate etching of the surface of the wax mould Increase the amount of wetting agent in the top coat. |
Low density of the top coat, resulting in an undense coating | Reasonable configuration of the surface layer of refractory powder particle size, in order to improve the powder-liquid ratio of the paint slurry |
Top coating mixing time is short, not stirred evenly, binder and powder wetting is not enough | The paint should be well mixed |
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Topcoat layer too thin, penetrated by grit | Increase the viscosity of the paint slurry Pay attention to the paint slurry shaking, empty material to moderate If necessary, the top layer of paint using 1-3 times dipping, coating |
Surface sanding material is too coarse | Use of finer grit abrasives |
Inappropriate method of spreading sand | The surface layer should be sanded by rain Modules should not be too far away from the sieves. |