Tolerance for Bearing and Shafts

Quite often the bearing manufacturer will have recommendations for the clearances needed for the shaft.

Additionally I find the information in my machinery's handbook. ( A common american reference book) Look under "fits"

Do you want the shaft to slide into the bearing?

Are you heating the bearing up and then inserting the shaft?

Are you having a key or setscrews hold the bearing to the shaft?

Bearing is not heated , hence I want the shaft to slide in the bearing.

If it were mine, I'd call SKF. Otherwise, I'd use +0/-0.062mm.

http://www.ntnamerica.com/pdf/2200/brgfits.pdf

http://books.google.com/books?id=O8Fcf-VIliwC&pg=PT508&lpg=PT508&dq=fit+tolerance+and+designations+%22bearings%22&source=bl&ots=6410SDfEgl&sig=0d5YcG1KkZJkDPnR5sDU1E-b31s&hl=en&ei=EjYUSujwIJ6ltgfHgqSaBA&sa=X&oi=book_result&ct=result&resnum=5#PPT508,M1

http://www.skf.com/skf/productcatalogue/Forwarder?action=PPP&lang=en&imperial=false&prodid=1140521210

Definitely, consult your bearing manufacture (SKF) about the requirements always. They have all those stuff mentioned in catalogs. The use of a different tolerance, although may be right, could lead you to loose any warranty is problems occurr. Also, as you're using a mounting bushing/sleeve, the sleeve may have its requirements too. I used to have such catalog with me, but I'm sorry to say that I just cannot find it now... its old, and I don't have electronic copies.

This is a bearing with taper sleeve (1:12 or 1:30 split types with lock nut?)

Here the bearing fits are decided through pre-loading of the sleeve by locknut tightening.

The usual tolerances maintained in these cases are h6 or at the extreme h7

for 45mm this is +00/-16μ or +00/-25μ)

our shafta are larger >300mm dia, however the same principle apply.

All the required data is included in the technical section of the SKF catalog or any other bearing manufacturer catalog.

The bearing fit is dcided by various factors, such as application,clearance of the rolling elements (C3,C4 etc.). I beleive the shaft size shoudl be 45.015 to 45.030mm

Alterntively,Go the SKF site,fit selection

sorry i think always shaft size will be lees than nominal size

The Design Engineering......if you grab your machinist handbook or your mechanical drafting book they have limits and fits tables in them. You will need to select a type of fit them it will give you a upper and lower limit for both the bore and shaft.

If you dont have these books drop us a line via our website at http://www.alnoproducservices.com.au and i can look it up for you

Anthony

just hammer 45 O.D. shaft into 45 I.D. bearing. i always does and it works

What industry are you working for? I assume it is not aerospace!! When you say "45 O.D. shaft into 45 I.D. bearing" what is the actual dimension of the shaft? are you checking it all? How do you know it is not 45.5 or 44.5 for example?

If shaft to be rotates without slip with bearing inner race & outer race to be fixed in bearing housing; then transition fit for shaft with inner race & close location fit for outer race with housing bore. Vice-a-vice for reverse case.Pls.find the respective machining tolerances from ISO std. tolerance tables.

One of the bearing races(either outer or inner race) should have transition fit like H7m5 or H7k6 (ISO standard) & the other one should have close running fit as H7h6 of ISO; with the respective mating part i.e.shaft with inner race & bearing housing with outer race. This works well with non fluctuating, light or medium load conditions. For heavy duty fluctuating loads, ISO suggests to go for srink fits by heating the bearing in suitable oil media for 25-40 minutes & assy. in hot condition. you may refer to ISO or BIS standard, reprinted in machinery hand book or PSG design data book for the same. best luck. sanjay