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Pin Force

Pin Force

Pin Force

(OP)
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

RE: Pin Force

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
 

RE: Pin Force

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.

RE: Pin Force

Hi metman

Thankyou

RE: Pin Force

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

RE: Pin Force

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

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