Heat and oxygen can change the properties of a rubber grommet during storage and service. This process, called thermo-oxidative aging, may cause hardening, softening, cracking or loss of elasticity. The response depends on the compound and exposure conditions.
Temperature and service life
There is no single temperature at which every rubber changes from oxidation to thermal degradation. The material, exposure time, oxygen availability and mechanical loading all matter. A short-term temperature limit should not be treated as a continuous operating rating.
Assessing an aged part
Inspect the grommet for cracks, permanent deformation and loss of retention. Compare relevant properties before and after an agreed aging test. Record the compound, test temperature, duration and acceptance criteria. An accelerated laboratory result does not, by itself, establish a service life in years.
For a replacement, confirm the actual operating conditions and select a compound with supporting data. Do not rely on appearance alone to judge whether a part remains suitable.
