Calculating Compressive Force on a Bearing based on Applied Torque

[Shinner]

I am currently using a screw assembly as a bearing to push a small steel ferrule on to a plastic tube. As the screw turns it slowly pushes the ferrule down over the tube while the opposing force acts agains the engaged threads.

Currenly using about 40 in-lbs of torque to completly secure the ferrule all the way on the tube (only a little more than .1" of total travel distance).

I want to change the assembly to a press fit action and eliminate the screw all togeather but I am not sure how to figure out the appropriate compessive force I am going to need.

Thanks for all the help.

 

[desertfox]

Hi Shinner

Well roughly speaking you can estimate the axial force from the torque using this equation:-

F = T/(0.2*d)

where F= axial load

T = torque

d = thread dia

0.2= friction factor for dry threads

If you know your interference you can use this calculator:-

http://www.meadinfo.org/2009/07/press-fit-pressure-calculator-optimize.html

desertfox

 

[geesamand]

The above formula applies to steel UNC threads or similar with light machine oil lubrication. (The 0.2 constant particularly).

However it should get you sufficiently close to design for a pure axial load installation.