Shop Practices – Handling Bearings

Not many of us have the opportunity to work each day in clean rooms like we see in articles about satellites and medical research. Most of us do not even work in a shop that is air conditioned unless you consider the open windows and bay doors as providing “air conditioning”. Consequently we have to always be on alert about the environment when we are working with rolling element bearings.

This applies from the day the bearings are received into the storeroom until the bearing is installed and in service. Prior to shipment, the bearings are coated with a preservative and sealed in a coated paper then sealed in a box. The manufacturer insures that the bearing is clean and ready for installation. But here are some of the shop practices that have been observed many times that will reduce the bearings life.

1. After withdrawal from the storeroom, the bearing is unwrapped and placed on the work table near where an old motor is being blown down with a high pressure air hose.

2. While installing, the bearing is dropped and bounces on the floor, but looks “O.K.”.

3. If 3oz of grease is good, then 5oz forced into the bearing and housing is better.

4. You don’t have a mounting tool but use a wooden hammer and just tap it gently  around the ring until it is seated.

5. Lunch time? Just leave the bearings on the cart, we’ll finish up when we get back.

6. Alignment is no big deal, just use a straight edge and line up the coupling halves.

Airborne particulates, depending on their size and material, will cause indentations when overrolled  and be the beginning of a spall which will lead to failure. Anytime a bearing is dropped, it should be discarded. The impact likely created    plastic deformations between rolling elements   raceways which depending on the location, can grow into a spall. The recommended grease schedule is designed for maximum life. Bearings are not designed to plow through grease and the churning will generate unwanted heat. Tapping on a bearing with any type hammer should never be done. Again plastic deformations can occur on raceways, reducing the life of the bearing. That bearing laying on the cart is open to all the particulates in the air. And finally, how many people can align two parts to within 0.003″ with just eyeballs and a straight edge. Misalignment is one of the most common causes of bearing failures.

Look around your shop, if this type of situation is present, make some changes and you will improve your bearings service life.

Find the original article here on SKF’s website 

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