Measurement using microindenter LNP

Measurement with the microindenter enables reproducible hardness measurements on practically all rubber articles and even on profile sections, which are based on the IRHD hardness. This means that hardness measurements can also be carried out on very small elastomer parts, composite parts or rubber-coated sheets. Spatially resolved measurements on profile sections of damaged parts are also possible. Furthermore, a spatially resolved parameter for the network density can also be determined. By moving the indenter in and out by means of a force ramp, the ratio of energy introduced and energy released is determined. The difference depends on the network density (dissipated or relative dissipated energy) and thus provides information about the degree of cross-linking at the tested point. If a comparative sample of the tested formulation with a known compression set is available, the quality of the degree of cross-linking can also be assessed. Automation makes it possible to analyze complete cross-sections of seals and elastomer parts in this regard. We have been using this method for damage analysis and for special finished parts since 2019.

Since March 2025, we have been using a specially developed microindentation system for the high-resolution analysis of rotary shaft seals (RWDRs). The so-called LNP analysis (Localized Nano-Property) is carried out automatically on up to eight test specimens in parallel and provides reproducible mechanical characteristic values after dynamic oil compatibility tests. The two-stage test procedure initially consists of tactile measurement of the running track, followed by position-accurate microindentation measurements in the center of the contact zone. Parameters such as stiffness and dissipated energy are recorded in order to quantitatively evaluate local material changes due to thermal or chemical stress. The LNP analysis thus enables an objective, data-based assessment of seal integrity and represents a significant step towards the standardization and digitalization of seal testing.

Your advantages at a glance:

• Automated testing of up to eight seals simultaneously
• Two-stage process: Tactile measurement of the running track and precise microindentation at 20 positions per seal
• Objective assessment of stiffness and dissipated energy to detect thermal or chemical damage
• Dual evaluation: combination of classic testing and data-based microindentation
• Setting the course for the future: a step towards standardization and digitalization of gasket testing

We are working with OEMs to establish this technology as the new industry standard.