Second-Generation Stucco Mixtures Build Investment Casting Shells Rapidly

摘要

New stucco compositions that combine fused silica, molecular sieve, and activated alumina, are designed to be used with conventional slurries and to be applied using hand or robot dipping in fluidized beds, or with the rainfall method. Cycle time from pattern to poured metal is important for a foundry's productivity and profitability. Shortening the time to build a shell can decrease this cycle time. Previously, we developed stucco compositions that contain an amorphous mineral silicate (AMS) additive and built shells rapidly. These compositions could be used with standard slurry and applied using fluidized beds and the rainfall method. The AMS additive works well, but it has an underlying dust problem because of the very small size of the AMS particles. We successfully eliminated the dust by applying a small amount of guar gum and polyethylene glycol 300 (PEG 300) to coat the stucco mixture. These are coatings that industry uses to coat materials with very fine particle size to reduce dust problems. But, because we only used small amounts of stucco for the tests, the amount of coating that was applied was hard to control, which would have been solved by going to much larger batch sizes. We looked for other stucco mixtures that would not have dust issues.