Does a low speed ball bearing need to be preloaded?
Does a low speed ball bearing need to be preloaded?
(OP)
I am working on a low cost, low margin, high volume robotic's project. Tho make use of very small motors the system is heavily geared, and as a result the output speeds on the drive shaft and leadscrew assy are relatively low. They are 500 to 1000 rpm. The motion profiles are 1/3 , 1/3, 1/3, and so the acceleration ramp is not excessive, in the .18m/s^2 range. Historically the company I work for has not pre-loaded their bearings and been fine over millions of robotic cycles, but I am looking for a way to substantiate that the preload is not necessary versus saying it will probably work. If I can ditch the preload mechanisms it will greatly simplify my assy and reduce the cost. Bearing manufacturers tell you to preload, but I have not seen any standard way of determining if you really need it or not.





RE: Does a low speed ball bearing need to be preloaded?
Preload is also recommended by bearing companies when you have high accelerations to prevent skidding during start-up.
In your post you say that the current system performs OK, so "if it ain't broke, why fix it?"
If you want a cheap preload system have you considered (and is it practical to use) a simple preload spring or wave washer which is neither difficult to implement nor expensive?
Lester Milton
Telford, Shropshire, UK
RE: Does a low speed ball bearing need to be preloaded?
RE: Does a low speed ball bearing need to be preloaded?
As the English Muffin suggests, if you do not
need stiffness in your application, there is
nothing wrong in using a small amount of
clearance. The repeatability of the robot
should be the same if the same loads are
applied repeatedly. If you change the bearing
which has a different clearance, you would need
to recalibrate the robot for the clearance
difference.