Why Is My Rotary Seal Overheating and Hardening

When a rotary seal begins to overheat and harden, it is often a warning sign that the sealing system is operating under unfavorable conditions. This problem not only reduces sealing efficiency but also increases the risk of sudden leakage and equipment damage.

One common cause is excessive friction at the sealing interface. If the seal lip is running dry due to insufficient lubrication, friction rises rapidly, generating heat. Over time, this heat causes the elastomer material to lose elasticity, resulting in hardening and cracking.

High operating temperatures within the machine can also accelerate seal degradation. Rotary seals are designed to work within specific temperature ranges. When surrounding components, fluids, or ambient conditions exceed these limits, the seal material may thermally age, becoming stiff and brittle much earlier than expected.

Another important factor is incorrect seal material selection. Not all elastomers respond the same way to heat, speed, and chemical exposure. Using a material that is incompatible with the application’s temperature or fluid can lead to rapid hardening, even if the seal is installed correctly.

Shaft misalignment and vibration further contribute to overheating. When the shaft does not rotate smoothly or runs off-center, the seal lip experiences uneven contact and localized heat buildup. This uneven stress accelerates wear and heat-related damage.

Lastly, contamination and poor heat dissipation can worsen the issue. Dirt particles increase friction, while thick or degraded lubricants may trap heat instead of carrying it away. Both conditions raise the operating temperature at the seal lip.

In conclusion, rotary seal overheating and hardening are typically caused by friction, excessive temperature, material mismatch, mechanical misalignment, or contamination. Identifying and correcting these issues early helps restore proper sealing performance and extend the seal’s service life.