Press fitting B4.1 FN

[kakalee1]

I am having problems with press fitting tolerance. On a drawing, it is called out to press fit a dowel pin per ASME B4.1 FN 1, so I looked up the table for a .250 dowel pins. According to the table, my interference should be from .1 to .75 thousandth of an inch. Now, is this interference for similar metal such as stainless to stainless steel or aluminum to aluminum. The part that I have is made of peek and the dowel pin is stainless steel, and it feels really loose sometimes.

I just want to find out if following the standard is appropriate for dissimilar metal. If it is not, how do you calculate the interference to get the equivalent fit?

All helps are appreciated.

 

[arbreen]

The FN fits are designed for steel shafts going into steel and cast iron, which are much stiffer materials and therefore provide much more bore pressure than PEEK. You can find equations to calculate bore pressure online with a search like "press fit equations". However, PEEK may simply deform under the same pressure that FN1 gives in steel. I would just make the hole a thou smaller and see if it works as originally intended. Oversized dowel pins may also be an option for you if your parts are already made.

 

[ctopher]

I agree with arbreen.
I have used PEEK for this. Normally I press-fit a sleeve into the PEEK, then press-fit the alignment pin into the metal part.

Chris, CSWA
SolidWorks 14
SolidWorks Legion