Whether pressure boundary or preventing fluid mix, the rubber seal is your line of defense. Here's how some designers guard against wear and leak.

Ideally, your rubber seal should have just enough contact pressure to resist or correct. No more. No less.

Unfortunately, you've discovered surface roughness. The shaft, once polished, is no longer smooth. There is abrasion and heat.

Assuming bulk material properties are met for shaft and seal, including hardness, geometry, temperature, and chemical compatibility, consider self-lubrication.

No matter your seal must remain natural, neoprene or nitrile rubber. The aim should be to transform surface properties, only. And what better way than to add a thin film of dry lubricant.

Compounds like PTFE (polytetrafluoroethylene), graphite, MoS2 (molybdenum disulfide) and WS2 (tungsten disulfide) can effectively reduce wear on the rubber seal. Keep in mind low friction will also benefit shaft surfaces through film transfer.

Consider treating the shaft, too. Hard, corrosion-resistant finishes like nickel, chrome, or a ceramic nitride or oxide may be ideal.

External lubrication is often imperfect. That's why your next shaft, o-ring, gasket or other seal design should include a self-lubricating coating.