When selecting retaining rings for an application, there are a number of factors that determine the right decision.
The first question to ask is what kind of assembly does the application require; is it a housing assembly or shaft assembly? Next, determine the main critical dimensions. These include the housing or shaft diameter, groove diameter, and the groove width. Also, what is the rotational speed (usually in RPM) of the assembly?
Next, determine the maximum thrust applied to the ring. Generally speaking, this can be thought of in terms of light, medium, or heavy duty loads. Maximum thrust is important because it will help determine if groove deformation or ring shear could be a problem. Basically, groove deformation occurs because the groove material is soft, limiting maximum capacity. Ring shear, on the other hand, occurs when the groove material is hardened, which also limits maximum capacity.
Retaining ring materials can include stainless steel, various alloys, carbon tempered steels, or bronze, among others. Other factors, such as the temperature as well as the presence of any corrosive media, can also impact the choice of ring material.
A related consideration is the material finish. This can include an oil dipped finish (for carbon steel rings), vapor degreased and ultrasonic cleaned (for stainless steel rings), or black oxide or a phosphate coat, among other choices. Also, does the ring need to meet any special standards, such as MIL or Aerospace standards?