calculating rotational torque limit based on press fit 3

[Rustang]

I'm looking for information on calculating how much rotational torque and axial force a pressed fit steel hub on a solid steel shaft can withstand before slipping.

 

[desertfox]

Hi Rustang

Here are the formula you need:-

Torque that can be transmitted by an interference fit
without slipping:-

T= f*Pc*3.142*d^2*L/(2)

where f=friction coefficient
Pc=contact pressure between the two members
d=nominal shaft dia
L=length of external member.

to calculate Pc for a given interference use the formula:-

Pc=x/[Dc*[((Dc^2+Di^2)/(Ei(Dc^2-Di^2))+....................
((Do^2+Dc^2)/(Eo*(Do^2-Dc^2))-((Ui/Ei)+
Ui/Eo))]



where x = total interference
Dc=dia of the contact surface
Di = dia of inner member
Do= outside dia of outer member
Uo=poissons ratio for outer member
Ui=poissons ratio for inner member
Eo=modulus of elasticity for outer member
Ei=modulus of elasticity for inner member

This formula for Pc will simplify if the materials are the same.
Hope this helps

regards desertfox

 

[Billcorr]

Nice work, I will save this for future reference.

Bill Corrigan

 

[Rustang]

Thanks for the input Desertfox. I do have a question, however. I'm assuming that Dc is the inner diameter of the hub, and Di is the diameter of the shaft?

Thanks again,
Rustang

 

[Rustang]

One more question! What should I use for a friction coefficient? (steel on steel)

Rustang

 

[desertfox]

Hi Rustang

to answer your last questions:-

Di = the inner dia of the
inner component ie:- a
tube, this is zero for
a solid shaft.

Dc = outside dia of the
inner member (o.d. of
shaft)

Finally for steel on steel (dry) the friction coefficient
around 0.25 but can vary below this depends on surface
finish , if you want to give a margin of safety use a friction factor around 0.15.

good luck

desertfox