Selecting a Radial Shaft Seal
Deciding on the type of radial shaft seal is a challenging process that requires selecting specific seal design characteristics to match the system parameters. The design engineer should organize the potential parameters and prioritizes them in order of severity and importance. At the end of this chapter is a Radial Shaft Seal Parameters Sheet that will help organize these requirements. Performing this exercise will help clarify the driving variables of the sealing system.
The beginning of this chapter focused on the education of how radial shaft seals work and the parameters that affect a seal’s environment. Using that knowledge to scan over a completed Radial Shaft Seal Parameters Sheet will help in selecting a few key parameters that will limit the profile selection. The more familiar you are with radial shaft seal parameters and their affects on sealing, the more comfortable you will be in selecting seal design variables. Selecting a radial shaft seal profile requires deciding the following: lip type, case type and the use of a hydrodynamic aid. There are many different radial shaft seal profiles available in the industry. All of these choices can be a challenge to a design engineer who does not know why certain lips and case geometries are used. For the purposes of design discussion, most case geometries can be paired with a lip style and vise versa. A hydrodynamic aid can be added to the primary lip of most spring loaded lip styles. All three of these design variables need to be considered separately and then combined to form a radial shaft seal profile.
For starters, first consider the application basics. This will help to narrow the lip selection immediately. The Application Study below provides an example of a common separation that usually requires different lip styles. Developing your own Application Studies that are specific to your industry is a valuable selection tool. Use the following guidelines for profile selections:
- Application Study: Grease vs. Oil Retention
- Lip Selection
- Case Selection
- Hydrodynamic Aids
- Custom Profile Design
- Radial Shaft Seal Parameters Sheet
Once these design variables have been chosen, a radial shaft seal profile can be selected (See Profile Matrix).