Relation - Internal Clearance to Press Fit

[iucu]

Having a Bearing like 35 x 62 x 14 with internal clearance about 0.012 how can I make a relation to Press Fit TOLERANCE on ID
How much press fit is too much ? to kill the internal clearance ...
That is not my goal at all but the press fit can be calculate with relation to internal clearance ?

 

[BrianE22]

I suppose you could look at the outer race thickness and do a calculation. Your bearing manufacturer, though, should have that info for you.

 

[Tmoose]

Most of the thicker bearing catalogs talk to this.
First, they will have recommended housing and shaft Diameter tolerances based on loading, application etc.
Does for some reason your application require shaft diameter other than k5 fit ? ( nominal +1 to +17 um ?

I think in the thickest bearing catalogs, with major engineering sections, you may read there is a general relationship around 80% between diametral interference and diametral clearance lost.

 

[BearingDave]

The reduction of clearance caused by an interference fit is something available in the bearing engineering books.


The rule of thumb I use is 80% of the interference between the inner ring and the shaft will become the reduction of clearance in the bearing.

In your example, the 35 x 62 x 14 mm bearing is most likely a 6007 deep groove ball bearing.

The bearing inner ring bore has by ISO standards a diameter of 34.988 to 35.000 mm.

A k5 machining tolerance applied on a 35 mm shaft means the shaft is 35.002 to 35.011 mm.

This means the interference between the inner ring and the shaft, when the bearing is mounted on the shaft, is between 0.002 and 0.023 mm.

80% of this interference is 0.0016 mm to 0.0184 mm. This is the amount of clearance reduction in the bearing from the action of installing the bearing tight on the k5 machining tolerance shaft.

A normal clearance class 6007 bearing has a radial internal clearance range of 0.006 to 0.020 mm.

Applying the reduction of 0.0016 to 0.0184 mm to this clearance range, you may end up with a final clearance after mounting ranging between -0.0124 and +0.0184 mm. A negative clearance indicates a preload.

You can therefore see that due to manufacturing tolerances of the bearing bore, radial internal clearance, and shaft, you could end up removing the entirety of the clearance in the bearing.

Many high speed applications, like electric motors, suggest a standard clearance class of C3 for ball bearings, since the high speed operation reduces the clearance further.

A C3 clearance class 6007 bearing has a radial internal clearance of 0.013 to 0.028 mm.

If we were to apply the same reduction (from the k5 machining tolerance shaft) of 0.0016 to 0.0184 mm, the end result for the C3 bearing is a clearance range between -0.0054 mm and 0.0264 mm.