Silicone prototypes 3D printed additive tooling

Due to their flexibility, silicones and elastomers offer an indispensable advantage for many technical applications. They are often used for seals, damping, flexible diaphragms or overmolded for soft/grip surfaces on components that make contact with humans. In contrast to additive-only rapid prototyping processes, injection molding also offers the advantage of smooth surfaces and optimal mechanical properties.

Silicones

Silicones have a wide range of interesting properties. For example, they are usually extremely temperature-resistant, have a high chemical resistance and are often biocompatible. In contrast to thermoplastic materials, silicones are not shaped by heating and cooling. Instead, two components are mixed together and then pressed into the mold. Vulcanization then takes place. A distinction is made between two groups of silicones:

• Room Temperature Vulcanization (RTV) Silicones: In this group of silicones, cross-linking takes place at room temperature.
• Liquid Silicone Rubber (LSR): In this group of materials, cross-linking takes place in the mold at elevated temperatures, usually above 150°C.

Injex only processes RTV silicones with shore hardness of 25, 40 or 60 Shore A.

Thermoplastic elastomers (TPE)

Thermoplastic elastomers (TPE) can be processed like conventional thermoplastics by injection molding. As a result, they are usually less expensive than silicones and also have a wide range of properties and advantages.

Thermoplastic elastomers (TPE) include

• TPU - urethane-based
• TPA - thermoplastic polyamide elastomers
• TPV - thermo-plastic vulcanizates

Silicones and elastomers in additive manufacturing

Until now, silicones can only be processed in very few 3D printing processes. These processes are mostly still in their infancy, but give hope for the future. Nevertheless, it is almost impossible to obtain surfaces of equal quality to injection molding.

TPEs can mainly be produced using the FDM/FFF and SLS processes. Both methods result in very rough and ribbed surfaces meaning they are not well suited for applications where predictable bending or tension are required, as non-uniformities result in inconsistent and high stress concentrations.

Also for many applications in the sealing sector or when optical properties are required, these processes can not be used.

«Additive Tooling» for fast silicone and elastomer prototypes

The injection molding prototype tools manufactured by Injex are excellent for the production of silicone and even elastomer components. With our prototype service, technical components in different Shore hardnesses and colors can be tested, validated and, if necessary, adapted in less than a week.