Retaining rings are not only known for replacing traditional fasteners and reducing installation and material costs, but also for the many unique and creative ways they can be used. In this use case, E Retaining Rings were used in place of conventional fasteners as an ideal device for a medical application.
The pump problem
Peristaltic pumps are used to move fluids along a tube in a variety of medical and industrial applications. They can pump sterile or harsh fluids without coming into contact with other components of the pump, which can contaminate clean fluids or become damaged from acidic or viscous fluids.
Here, eight rollers are held in place by E Retaining Rings. An E Ring also retains the entire wheel that the rollers are attached to.
The core of the pump in this design is a series of rollers that are fastened to a wheel. A tube containing the fluid comes in contact with the rollers as they turn. The rollers pinch the tube to force the contents in the tube to move along.
As the tube returns to its natural “un-pinched” state — between each roller — the force causes additional fluid to move through the passageway, keeping a steady flow through the pump. This is typically referred to as a form of positive-displacement pumping.
This process is called peristalsis and is used in many biological systems, most famously in the gastrointestinal tract. Common applications for peristaltic pumps include heart-lung machines, to circulate blood during bypass surgery, and in hemodialysis systems.
However, in one case, designers were particularly concerned about the extra costs associated with retaining eight separate rollers on their own shaft using traditional fasteners — such as screws, nuts, and bolts. Limited space was also a consideration along with the costs associated with assembling so many small components.
The retaining ring solution
Ultimately, the E Retaining Ring became the fastener of choice because it offered the designers the following advantages:
- Less shaft preparation (no threading, tapping, or drilling)
- Reduced weight and size of finished designs
- Lower costs of raw material and labor in assembly of components.
Retaining rings are metal fasteners that are installed into a groove on a shaft or in a housing or bore creating a shoulder that retains an assembly. They eliminate threading, tapping, drilling, and other machining operations associated with more traditional fasteners like screws, nuts, bolts, cotter pins, washers and more. They can significantly reduce production costs since the grooves can be machined with other production processes.
Overall, these rings provide a more compact, functional design than their traditional counterparts. Learn more here.
Rotor Clip Company
www.rotorclip.com
Filed Under: Fastening + joining