Redesigning Parts for the Process

Here is a list of things you can do to produce stronger cast parts while increasing your silicone mold life.

Parts designed for the injection molding process generally have thin wall sections. Because they are made from thermoplastics, the part walls are kept thin to keep the material and production costs down. For thermoplastics, thinner walls also mean faster demold times. The opposite is true for cast polyurethanes. Thermosetting materials use chemical reactions when A & B components are mixed, and the exotherm heat generated cures the polymer to a final part. The thicker the part is, more heat is generated and the part cures quicker. Unlike thermoplastics, polyurethanes (thermosetting) can be demolded quicker with thicker walls. Thin wall sections can limit your polyurethane casting material selection due to the necessity of having lower viscosity material options only. So, for polyurethane cast parts, add wall thickness where possible. This will help strengthen your part and decrease your demold time.