There are several important silent assumptions of bearing reliability. However, before I address these assumptions, some even more basic assumptions and statements of fact must be established. While it might be a bit of a leap, I’m going to assume that the bearing is well-designed, well-manufactured, properly handled and stored, and finally, correctly selected for the intended application. With that said, we’re now ready to talk about those silent assumptions that are in the maintenance function’s domain.
These assumptions relate to the internal environment and duty cycle to which a bearing is exposed. Bearing manufacturers will frequently report that only a small percentage of bearings reach their fatigue limit (catalog life). According to one major supplier, typically only 10 percent of rolling element bearings reach their L10 life (it should instead be 90 percent by definition). The old saying that bearings don’t just die, they’re murdered, is rooted in fact. For a bearing to have a normal life expectancy, it is assumed that the following, often unspoken, root causes of failure (our silent assumptions) will not occur at any time after commissioning.
Mechanical Causes
Exceeding a bearing’s dynamic load rating translates to a disproportionate reduction of fatigue life. For most bearings, doubling bearing load can reduce bearing life to roughly one-eighth of its normal life. Mechanical assaults on bearings by misalignment (Figure 1) and unbalance can produce similar consequences.
There are many vital lubricant properties that when altered or impaired can sharply diminish bearing life and reliability. These include such things as additives (AW, EP, etc.), acid number, lubricity, viscosity, pressure-viscosity coefficient and viscosity index. Using the wrong lubricants, degraded lubricants, mixed lubricants (including incompatibility) and/or contaminated lubricants can cause a loss of fluid properties.
Fluid Contamination
The “most wanted” fluid contamination assassins include dirt, water (Figures 2 and 3), fuel, glycol and soot. However, there are many others – too long to list here.
Heat too is a contaminant. Its aggressive tendencies can be dependably viewed as both a cause and effect of most types of fluid and mechanical problems – including many of those found elsewhere on this list. Overlubrication (too much grease) is a common cause of heat in grease-lubricated bearings.
Starvation
A surprising number of bearings are simply starved to death. Over time, they run dry of lubricating oil or grease unless properly and frequently relubricated. The wrong relubrication intervals are often the culprit, but such things as cold starts, dry starts and grease bleed problems can also contribute to starvation. …
… Other contributors of starvation relate to the failure of lubricating mechanisms such as flingers, slingers, rings, single-point devices, oil mist, oil pumps, centralized systems, etc.
While it is true that a bearing damaged from fatigue or wear won’t heal over by itself, it also won’t tell you where it hurts unless you ask. To be attentive to bearing reliability you must tune into these silent assumptions and their symptoms. This is where oil analysis can play an important life-extending role.
If you review each item in my list of silent assumptions, you will discover that, surprisingly, oil or grease analysis can in almost every instance call attention to these concerns, either directly or indirectly. When things go wrong, both the causes and symptoms of a problem are often revealed by the oil’s properties and contaminants. In fact, the alarms are silent only when you choose not to listen. To listen, you must:
sample correctly,
sample at the right frequency,
run the proper slate of tests,
set alarms and limits correctly,
possess suitable knowledge of data interpretation, and
timely and appropriately respond to nonconforming conditions.
Too often, oil is changed without real cause. Imbedded in the oil is a message about its health, the bearing’s health, contamination and other vital properties. We lose this message when the oil is changed without sampling. After all, problems such as misalignment or coolant leaks are never solved simply by an oil change alone. In such cases, changing the oil results not only in ultimately murdering the bearing but shooting the messenger as well.
It never ceases to amaze me that no matter what industry you are in or how big or small of a company you work for, success is dependent on the ability to find, attract, hire, manage, develop and retain the right people. I continue to see companies disproportionately dedicate more focus and investment into non-people issues such as technology or equipment than focusing on getting “the right people on the bus.” I haven’t quite figured out why, but I believe it could boil down to one of three reasons:
It never ceases to amaze me that no matter what industry you are in or how big or small of a company you work for, success is dependent on the ability to find, attract, hire, manage, develop and retain the right people. I continue to see companies disproportionately dedicate more focus and investment into non-people issues such as technology or equipment than focusing on getting “the right people on the bus.” I haven’t quite figured out why, but I believe it could boil down to one of three reasons:
There are three significant trends that are causes of concern for the real estate industry and large enterprises globally in 2023. While most of these are common problems real estate owners and operators encounter, they threaten the very existence of such businesses during economic downturns. How do they keep themselves afloat and profitable? Real estate owners and operators are turning to technology solutions to find ways to curb spend and improve bottomline in 2023 and beyond.
There are three significant trends that are causes of concern for the real estate industry and large enterprises globally in 2023. While most of these are common problems real estate owners and operators encounter, they threaten the very existence of such businesses during economic downturns. How do they keep themselves afloat and profitable? Real estate owners and operators are turning to technology solutions to find ways to curb spend and improve bottomline in 2023 and beyond.
When you ask front line supervisors or team leaders if all people in their teams are performing to the same standards or if some are doing more work and achieving more results than others, you will often get the same answer. All over the world, the most common answer, after some analysis, verifies that about 30% of the people do 70% of the work.
When you ask front line supervisors or team leaders if all people in their teams are performing to the same standards or if some are doing more work and achieving more results than others, you will often get the same answer. All over the world, the most common answer, after some analysis, verifies that about 30% of the people do 70% of the work.
The way we see maintenance work being done, you have preventive maintenance which is done is to prevent a failure or to detect a failure early. Continuous improvement, you may have some those, those are the things to be done from redesigns. I can see you doing that in two cases...one is if you have a root cause and you see whatever you have a problem on you have a piece of equipment that is not working right...you may have to redesign it.
The way we see maintenance work being done, you have preventive maintenance which is done is to prevent a failure or to detect a failure early. Continuous improvement, you may have some those, those are the things to be done from redesigns. I can see you doing that in two cases...one is if you have a root cause and you see whatever you have a problem on you have a piece of equipment that is not working right...you may have to redesign it.
How does the current state of leadership affect employee engagement? What is the effect of both good and bad leadership as it pertains to organizational health and engagement? From a leadership perspective, who actually is responsible for employee engagement?
How does the current state of leadership affect employee engagement? What is the effect of both good and bad leadership as it pertains to organizational health and engagement? From a leadership perspective, who actually is responsible for employee engagement?
Today’s mining industry is facing a new set of challenges. Commodity price projections for the future remain uncertain, global demand remains high and there is a global labor shortage. While the mining industry remains highly competitive and essential to continued global economic growth, mining companies continue to search for ways to sustain growth and profitability.
Today’s mining industry is facing a new set of challenges. Commodity price projections for the future remain uncertain, global demand remains high and there is a global labor shortage. While the mining industry remains highly competitive and essential to continued global economic growth, mining companies continue to search for ways to sustain growth and profitability.
In some organizations, reliability is not just a word, but a culture that has been built over a period of time. Developing a reliability culture is not solely a top-down approach or dependent on the company’s vision. Sometimes, it is taken as a normal, routine job, while other times, it may get a fast-track status.
In some organizations, reliability is not just a word, but a culture that has been built over a period of time. Developing a reliability culture is not solely a top-down approach or dependent on the company’s vision. Sometimes, it is taken as a normal, routine job, while other times, it may get a fast-track status.
