Key Takeaway: Trapped air in silicone molds is a primary cause of voids, surface pinholes, and incomplete fills in polyurethane vacuum casting. Effective silicone mold venting design often employs an application-dependent "Pour Low, Vent High" strategy, placing distributed micro-vent channels (with typical starting depths of 0.025 mm – 0.050 mm, depending on resin viscosity, mold durometer, and geometry) at highest points, blind pockets, and last-fill areas to facilitate air evacuation while minimizing resin flash. What Is Silicone Mold Venting?Silicone mold venting is the technique of engineering micro-slots, razor slits, or tubular channels into a silicone mold cavity to allow displaced…
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