Process Improvement to Minimize Fractures in Water-Soluble Mandrels

The sponsor makes water-soluble mandrels to create products ranging from musical instruments to aerospace modules. The mandrels are composed of silica and alumina cenospheres, polyvinylpyrrolidone, and sodium silicate, which are formed into blocks and solidified, or cured, using carbon dioxide, microwave radiation, and convective heating. Mandrels can shear and crack, causing product loss, so the sponsor charged the team with finding a cost-effective and feasible solution to overcome compromised mandrel strength. The team analyzed the production process and investigated three potential sources of product damage. First, material composition was analyzed for any inconsistency, impurity, or noninteractivity that might cause weakness. Second, various curing methods were explored, such as carbon dioxide curing of sodium silicate for structure, and microwaving and using a constant-temperature convection oven to dehydrate and strengthen the mandrel. Third, transportation was investigated as a potential source of mandrel stress and rupture.