ADDmold for LSR

The target batch size is 10 to 50 parts, each weighing 1 to 10 g. The main challenge here lies in the durability and precision of the molds. Another advantage is the cost of the mold, which is expected to be significantly lower than that of steel injection molds. Particular attention must be paid to the following properties:

• The effects of the molding parameters on the tool’s subsequent properties are unknown and must be determined. In particular, continuous temperature control in the range of 130–150 °C, combined with dynamic stress caused by the clamping motion of the injection molding process, must be included in the working hypothesis.
• Material aging of the mold increases with service life or depending on the process parameters. As the material ages, its mechanical properties—including stress, strain, tensile strength, and dimensional stability—will change.
• The thermal expansion of the printed plastic must be determined to obtain precise cavity dimensions and installation dimensions. This may depend on the printing process.

The purpose of these studies is to enable mold makers to use additive manufacturing for LSR molds in small- and medium-volume production runs in the future. This will allow them to save costs and respond very quickly to new products or product changes. Mold makers in this industry are almost exclusively small and medium-sized enterprises (SMEs).

Cured (150 °C, 10 min in the oven) LSR samples on two of the four inserts tested. Left: Mold insert made of Somos PerForm Reflect; right: Material sample made of EnvisionTec E-Mould.