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2 min read

What is Bearing Service Life? And Which Qualities Impact it?

By Dave Biering on November 7, 2017

What is Bearing Service Life? And Which Qualities Impact it?

We often talk about the importance of bearing service life in this forum, but what exactly is a good standard of measure to this question? The truth is, bearing longevity depends on factors beyond operating conditions. Here’s the rest of the story:

As defined by Machine Design, bearing service life is, “The life of a bearing under actual operating conditions before it fails or needs to be replaced.”

Simple enough.

But which factors contribute to how long you can expect your bearing to last in your “typical” environment? We consider these main factors:

1) Lubrication is critical

Without good lubrication levels (whether manually-greased rolling element bearings, or self-lubricated composites), bearing friction will build. Which means heat will build, and so, too, the possibility of bearing overheating and failure. Environmental factors like dust and contamination can also have a negative impact on lubrication (causing a lapping compound to form around the hardware), which will result in a shorter bearing service life. Good lubrication is very important.

2) Bearing load is a key contributor

Knowing the full load potential of an application is key to determining bearing lifetime. This is especially true with cantilevered and uneven loads (as in construction equipment lifting applications). Best practice is to “overdesign” a bearing by overestimating the highest load it may encounter in order to leave some room for additional weight.

3) Operating temperatures (not too hot!)

Matching the right material formula to the anticipated temperature, as we recently explored, Bearing Temperatures and Plastic Composites) Temperatures impact press fits and the thermal expansion, which, in turn, impact the tolerance between the shaft and the ID of the bearing. These all contribute to the total service lifetime of the bearing.

4) Speeds are important, too

Bearings that are improperly matched to the SPM (or speed for minute) of the rotary application will wear more quickly and have a detrimental impact on service life. Good bearing alignment is also important.

While the above are the primary contributors to how long you can expect a bearing to last, it’s important to also consider additional factors like material storage. Some materials, like etched-PTFE Rulon, require a UV-blocking bag or else the etching will degrade in standard warehouse conditions. For best results and longer service, bearing materials must be stored and handled properly. Read more about bearing wear.

Ultimately, the better a bearing is matched to your application environment, the longer it will last. We can help guide you to the right material!

Bearing Selection: Get the Ultimate Plastic Bearing Design

Topics: Bearing Service Life
2 min read

Common Causes of Bearing Failure

By Dave Biering on October 16, 2014

Common Causes of Bearing FailureWhy do bearings fail?

Unfortunately, there is not one simple, one-size fits all answer to this question. When we evaluate bearing materials for any application, we also examine why previous materials may have failed. We look at operating conditions, running temperatures, lubrication issues, fatigue factors and more to determine the root cause. It is the culmination of all of these ― plus many other factors ― that contribute to bearing service life. Here’s a quick review of common causes to help you avoid bearing failure in the future:

Although it can be difficult to determine the exact cause of a bearing failure, some major causes include:

  1. Bearing lubrication – without the right lubrication levels, bearings can overheat and wear prematurely, which can significantly increase your replacement and maintenance costs. Lubrication failures can result either by using the wrong lubricant, insufficient lubrication or even a total breakdown of lubrication. Another challenge with lubricated bearings is that the excess grease can attract dust and other contaminants which can reduce service lifetime. Self-lubricating plastic bearings eliminate all of these concerns since they run “dry” without any additional lubrication.
  2. Working conditions – What are the everyday conditions that your bearings are exposed to? Do they regularly encounter cleaning chemicals, corrosive salt water, construction dust or other debris? It is critical to match bearings to the correct working environment. For instance, Rulon J offers superior performance in a diverse range of applications. It gives good wear, friction and temperature stability, but is not the best choice for use in wet environments. Explore the benefits of Rulon J after treatment with Plasma Surface Modification.
  3. Shifting and misalignment – After hundreds of hours of use and stop/starts, equipment bearings can slide out of place. This can signal the end for metal bearings, while other materials are specially designed to accommodate shifting concerns. Ultracomp bearings, for instance, are a good choice for the construction, oil and gas and rail industries where heavy loads and constant use contribute to shifting.
  4. Temperature - Many designers still believe that a thicker bearing wall can resist higher temperatures than thin-walled plastic bearings. In fact, heat buildup is much more likely with thick-walled bushings. Consider plastic bearings for good heat dissipation and a higher-PV value.

Have you experienced a recent bearing failure? Share your experience here and we can help you explore different bearing options!

Topics: Bearing Failure Bearing Service Life