SHAFT & HOUSING TOLERANCES 2

[Flanken]

Hi to all,

We are using high speed woodworking machinery in our plant. One of our machine give up, the bearing seat in front of the shaft worn out. Can you inform me for selecting the best tolerances for shaft & housing of high speed 7208E O arrangement angular contact bearings.

Thanks,
FLANKEN

 

[Biggadike]

Have you tried SKF - the bearing company. They have a very full description of tolerances listed in their catalogue for all bearing types.
You might want to consider a bearing lock (loctite type) product on the interface as well to stop any slip between parts and a repeat of the previous failure.

 

[FINN_imported]

If you try the adhesive "part locker" (i.e. LOCTITE from Permatex), and you still have failure problems, you may want to look at material differences between the housing and the bearing. Keep in mind, if you have an aluminum housing and a steel bearing, you will have different rates of thermal expansion of the metals. This means, as the assembly heats up during operation, the aluminum housing expands faster than the bearing and you lose any "press-fit" tolerance you had between the bearing and housing.

One way I designed around this problem in the past was to "cast in" a ductile iron sleeve for the bearing bore in the housing. You can then design a better press-fit between the bearing and the housing. The materials are also a better match in thermal expansion and also for use of a "part-locker" adhesive. The downside to using this "fix" is that it can be costly.

I hope this helps.

Finn