Gasket design – What really matters, 
Smart solutions with TPE

In addition to material selection, manufacturing parameters, and component testing, gasket design is a key factor for success. It is not recommended to transfer existing geometries from previous projects using materials such as NBR, EPDM, or silicone 1:1 to TPE. Experience shows that neither simple O-ring geometries with a round cross-section nor complex multi-hump contours lead to optimal results with TPE gaskets. The reason for this is the plastic creep behavior of the thermoplastic components in TPE at elevated temperatures. Fine elevations lose their shape and heavily overpressed round cross-sections become flattened. In addition, a plastic-compatible component design is essential to ensure complete filling without weld lines and with as little residual stress as possible in the injection molding process. Only in this way can the gaskets withstand even demanding test conditions – whether in the usual temperature range of -40 to +80 °C or, with special compounds, even up to +120 °C.

The test values for thermoplastic elastomers shown in the technical data sheets, such as compression set, demonstrate the excellent sealing properties for applications in almost all industrial sectors. These range from strictly regulated medical applications and automotive components to consumer goods and industrial applications. When comparing different manufacturers and data sheets, it is important to always pay attention to test methods and temperature specifications. These characteristic values represent potential, which can, however, be severely limited by unsuitable seal design.

A successful sealing solution requires the right cross-sectional shape, sufficient material thickness, symmetrical geometries, clearance for thermal expansion, targeted force distribution within the component, and as little shear stress as possible. The overall system of the assembly must always be taken into account—often consisting of different materials with different thermal expansion coefficients and manufacturing tolerances. A basic understanding of these material and processing properties is essential for a functioning sealing solution.

In practice, an almost rectangular geometry with a thickness of more than 2 mm and a compression of around 20 to 30% has proven to be particularly advantageous. Such parameters should be planned during the design phase and simulated in the installation situation using digital tools—in close cooperation between design, project management, toolmaking, and material suppliers. Close cooperation results in a targeted, smart gasket design.