How to Safely Mount and Dismount a Bearing – Some Important Dos and Don’ts
Like any other moving part, bearings can wear over time and need replacing. Safely mounting a bearing makes all the difference in preventing premature failure of the part and unnecessary and expensive repair and replacement of related parts of your machinery. Incorrect mounting and dismounting will, at a minimum, cause excessive noise and vibration and affect the efficiency of your machinery. Want more information on How to Adjust a Bearing? In that case, don't forget to read our article.
Can You Use a Hammer?
Excessive use of force is never advisable. Using a hammer, while common, is really a shortcut to damaging your bearing or equipment.
Bearings are designed to withstand heavy loads, distributing those loads precisely and reducing friction between parts. They are, however, sensitive to sudden, powerful impacts, which can damage the bearing elements and affect its rotation.
Using a wooden block with your hammer, will distribute the pressure more evenly, but you still run the risk of causing damage. Unless, of course, you use a bearing fitting tool kit.
Heating a Bearing for Easier Fitting
Heating your bearing causes it to expand, so it will be easier to put in place. As it cools, it returns to its original dimensions for a snug fit. This applies when mounting onto a shaft.
Some people attempt to use burners and hobs but these are inaccurate and risky methods, particularly for parts with rubber seals.
The heat needs to be distributed equally, ideally at a temperature in the range of 80° to 90°C. Allowing the temperature to reach 120°C risks causing permanent dimensional changes and compromising the strength of the bearing itself.
Oil baths allow even heating, although it is vital that any oil residue remaining on the bearing is removed before mounting it onto your machinery. Another alternative tool is a heating cabinet, although here particular attention needs to be paid to the temperature and how evenly the bearing is being heated.
The best approach is to use an industrial heater which is designed for the task in hand and well worth the investment. It’s fast, efficient, automatically demagnetises and, because it is portable, can be plugged in to a standard electrical point anywhere.
You will find that when the outer ring is fixed into the housing, the entire housing will need heating to that same temperature. Where this cannot be safely achieved, using freeze spray or a combination of dry ice and alcohol can lower the temperature of the outer ring instead. Be careful not to reduce its temperature below the -55°C mark, as the housing may become brittle and fragile.
The Best Tools for Disassembling a Bearing
If you are removing a bearing and plan to use it again, which is increasingly rare but does still happen particularly for larger bearings, you will need to disassemble it just as carefully as you would when installing a new bearing. One method is to use an induction heater, in a reverse of the mounting procedure described earlier. The alternative is to use a Bearing Puller.
Once safely removed, clean the bearing with a suitable solvent, such as petrol, and inspect it closely for any damage. If it performs perfectly, it can be used again. If there is to be a significant delay between dismounting and reassembly, oil and store your bearing. If it needs replacing, you will need to make sure you are ordering the best bearing for the machinery and application. And remember, if you are not the only person to have maintained the machinery, it is possible that the wrong bearing has been used before. Always check the equipment manufacturer’s handbook for further information.
In Conclusion
Bearings are precision instruments and require careful handling, particularly during mounting and dismounting from machinery. If you are in any doubt about the best tool for the job, consult the machinery manufacturer’s maintenance document, or contact your Kramp account manager or product specialist for expert advice.
