Pin Force 1

[Creech]

Hello

I'm trying to determine the minimum and maximum force that we can expect in lbs measured after we press a pin into a hole.

The pin is .0582/.0578 Dia x .1 long 420 SS ground finish

The hole is .0579/.0574. 17-4 stamped in .055/.053 thick material 50/50 shear to break

No lubrication.

Averag Poissons ratio for steel at .288 ?

Coefficient of friction .8 ?

E 30,000,000 ?

Our customer is looking for something like 50 lbs min but I need to find out how to calculate the min and max with the given tolerance stack. Any help would be greatly appreciated. - Rich

 

[desertfox]

Hi Creech

Here are some formula that might help:-

Pa= f*3.142*d*L*Pc

where f=friction coefficient
Pc=contact pressure between the two members
d= nominal shaft dia
L=length of external member.
Pa= axial force required to interference fit
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 shaft
Di = dia of inner member(this is zero for solid shaft)
Do= outside dia of collar
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

 

[metman]

Not to detract from desertfox's helpful reply which btw I starred but also:

Machinery's Handbook has an excellent article on press fit vs shrink-fit calcl's and resulting forces to remove pin.

 

[desertfox]

Hi metman

Thankyou

 

[chicopee]

Press fit is widely covered in all Mechanical Engineering and Machinist handbooks that I have read over the years.

 

[chicopee]

Also, go no line and type "Press Fit"; All formulae on press fit are easy to apply.