Enhancement of the Long Life Cycle of Silicone Molds for Vacuum Casting Processes

Abstract

In this work we present a new method to enhance the durability of silicone molds, which are used in industrial processes for small batch production. The goal is to reduce the aging effects of the molds that occur after a minor number of casting processes and therefore get a higher output of these molds. First the source of the aging effects is identified. It is shown that the molds are nourished with the low molecular components of the polyurethane mixtures during the casting process, and that the diisocyanate component is responsible for the aging effects. For the removal of these components, several solvents are used. Acetone is shown to be most effective; the regeneration leads to a 30% higher output. Because acetone also removed free silicone oil from the molds, a mixture of the solvent with new silicone oil as regenerating agent was applied, which led to an overall improvement of lifetime of 60%.

Keywords:

• Aging
• Lifetime improvement
• Molding
• Silicones

Notes

The aging effect was evaluated haptically and optically on a scale from 0 (no aging) to 5 (intense aging).

Recovery after every 10 casting processes for 1 h.