Radial shaft sealing discussion

[ExoO]

Hello fello technicans

small introduction iam from the Netherlands and work as a R&D engineer. As fas as my experiances goes i start to think allot of engineers included my self do not have the right knowlage about radial shaft sealing.
Less than 20% of seals and gaskets ever reach their expected “operating life” in any given application. Of the 80% that are replaced due to scheduled maintenance, ineffective performance, or failure, 40% can be attributed to improper lubrication.

For now i would like to share knowalage about radial shaft sealing in the way of design and faillures.
theoratical a radial seal develops its seal through a pumping effect by interferance of seall lip and rotating shaft. Hereby there are allot of influnces on this.

What roughness/profiel is minimum for a proper working of the seal? I found that Microaperties are very important.
Some shafts that have been in operation for a few k's in running hours show running in profile were lip made contact. Hardness of profile is advised for 55-65 HRC.

 

[gerhardl]

To reach a sensible answer you have to assume that a lot of variables of construction, surroundings and process are constant and not influencing your result.

It will then boil down to how the lubrication film performs, depending again of lubrication type and behavior under the process conditions, among other perhaps temperature as one of the most important.

You can find an idea of influencing factors below or at similar pages:

https://www.plantservices.com/articles/2002/423/