Click mechanism on rotating plastic part

[AriRnD]

Hello, I am a newly hired mechanical R&D staff. Currently, I am working on designing a component for a medical device, and I am encountering an issue with one of the parts.

Below is the image of the sub-assembly component I am working on. The component can rotate from 0 to 90 degrees (The first image is when 0 degrees condition, second one is on 90 degree, and the third image is front view of the component), and at both the 0 and 90-degree positions, it is expected to have a click mechanism to secure these angles without adding additional components (such as springs, etc.). Do you have any suggestions or references for the design of this mechanism?

 

[3DDave]

A full radius with notches at the stopping points is typically used (blue part) with a spring and round-end bullet in the red part.

This is the lowest cost, reliable method.

I suppose you could replace the spring and bullet with a zig-zag of plastic feature that is molded as part of the red part. If the red part is acetal (Delrin(R)) that would help. It will be tougher to adjust the feel than using a spring as to tweak it requires a mold change.

Look up compliant mechanism design.

 

[Mech1595]

- How many rotation cycles do you expect this assembly to see over it's life?
- Will the mechanism have to resist any external forces, or just the weight of the components?
- Is plastic debris from repeated use a contamination concern in a medical environment?