The causes are well-documented. So are the solutions.
Why do bearings fail so quickly, and how to extend lubrication intervals?
Quick answer: About half of premature bearing failures are associated with poor lubrication or contamination: the wrong product, the wrong quantity, or contamination. By selecting the right lubricant, documenting routines, and applying advanced technology such as MicPol®, industrial companies demonstrably extend their lubrication intervals by a factor of two to twelve.
A bearing designed for a long service life can still fail prematurely when lubrication, contamination, installation or operating conditions are not properly controlled. The line stops. The team works overtime. In many cases, lubrication is one of the factors involved.
According to SKF, 36% of all premature bearing failures are caused by poor lubrication, and a further 14% by contamination. Yet most companies spend only 1 to 3% of their maintenance budget on lubricants. The damage caused by poor lubrication can account for 15 to 40% of the maintenance budget, depending on industry and current practice levels. This article explains the causes and what you can do about them. For a broader overview of how Interflon helps organisations address this gap, see Working with Interflon.
The 5 most common causes of premature bearing failure
1. Incorrect lubrication: too little, too much, or the wrong product
The most common cause. Under-lubrication can result in insufficient lubricant film separation, increasing friction, heat and wear. Over-lubrication is less visible but can also cause serious bearing problems. More in the next section.
Hardened and degraded grease on a shaft with bearing housing. The brown/beige, granular substance is a sign of lubricant breakdown caused by an incorrect product selection or an excessive lubrication interval, one of the most common causes of premature bearing failure.
Product selection matters just as much as quantity. A grease with the wrong viscosity, an incompatible thickener, or insufficient EP additives simply cannot provide the protection the application demands.
Note: some EP additives can cause copper corrosion when in contact with yellow metals such as brass or bronze. See the grease and oil compatibility table before combining lubricants.
2. Contamination: water, dust, and process chemicals
Responsible for around 14% of premature bearing failures. Water can reduce lubricant performance and promote corrosion. Solid contaminants can indent or abrade bearing contact surfaces, while process chemicals may affect seals, lubricant stability or corrosion protection.
Hardened and degraded grease on a shaft with bearing housing. The brown/beige, granular substance is a sign of lubricant breakdown, the degraded grease itself becomes a contaminant, accelerating raceway wear and premature bearing failure.
In environments with high-pressure washdowns or open production processes, contamination control is just as important as product selection.
3. Poor mounting
16% of bearing defects originate at installation. Incorrect fitting techniques, hammering on the bearing ring, and failing to check alignment introduce damage at the point of mounting that only becomes apparent during operation.
4. Misalignment
Misaligned bearings experience asymmetric contact stress. This accelerates fatigue damage and increases heat generation. Periodic alignment checks are a basic measure that is regularly overlooked in practice.
Asymmetric wear on the bearing raceway caused by shaft misalignment. Even a few tenths of a millimetre of angular or parallel misalignment is enough to concentrate the load on one side of the bearing, dramatically reducing service life.
5. Overloading and fatigue damage
34% of defects result from fatigue caused by overloading or incorrect maintenance, both mechanical and thermal.
Over-lubrication: just as damaging as too little
Over-lubrication is severely underestimated in industry. When a bearing housing contains too much grease, the rolling elements can churn through the excess grease, increasing frictional losses and operating temperature.
Higher temperatures accelerate grease ageing and can shorten grease life. Excess grease may also increase pressure in the housing and contribute to leakage or seal damage.
For grease-lubricated bearings, SKF uses a practical relubrication guideline in which the calculated interval is halved for every 15°C increase in operating temperature above 70°C, up to the grease's applicable high-temperature limit. The actual interval also depends on bearing type, speed, load, contamination and the grease used.
Recognise over-lubrication by grease escaping from seals, an unusually warm bearing position after regreasing, and increased energy consumption from the drive.
The solution is not less attention to lubrication, but more precision.
Read our whitepaper on over-lubrication
How do I extend my lubrication intervals? Six proven strategies
1. Select the right lubricant for the application
Viscosity, Viscosity Index, NLGI grade, thickener type, and additives must be matched to temperature, speed, load, and environment. A bearing on an electric motor in a clean, dry room requires a different grease than a conveyor chain in a meat processing plant.
Regreasing an incorrectly chosen product more frequently will never deliver the results that a correctly chosen product with longer intervals achieves. Understanding the 6 functions of a lubricant helps clarify why product selection is so critical. For an overview of the building blocks of grease, base oil, thickener and additives, see Properties of grease.
2. Always clean before lubricating
Clean the grease fitting and surrounding area before applying fresh grease to prevent dirt from entering the bearing. Routine relubrication does not necessarily require all existing grease to be removed: the correct procedure depends on the bearing arrangement, housing and relubrication method.
When changing to another grease, check lubricant compatibility first. If the products are incompatible, or the existing grease is severely degraded or contaminated, the old lubricant should be removed as far as practicable before introducing the new product.
3. Use the correct quantity and calibrate your grease gun
Establish the exact quantity required per lubrication point in grams, document it in the lubrication schedule, and calibrate the grease gun accordingly. Measuring how much grease the gun delivers per stroke is a one-time five-minute investment that structurally prevents over-lubrication.
4. Consider automatic lubrication systems
Single Point Lubricators and automatic multi-point systems can reduce the risk of two common execution problems: missed lubrication points and inconsistent quantities. Correct system design, lubricant selection, dosing and maintenance remain essential. Documented Interflon field results show up to 85% less lubrication labour time and 50 to 80% less lubricant consumption.
Explore lubrication tools and automatic lubrication systems.
5. Document everything in a lubrication database
Without documentation, lubrication management depends on the memory of individual employees. ILAC® (Interflon Lubrication And Control) records the product, quantity, interval, and execution method per lubrication point. The system supports audit preparation for ISO, HACCP, and ICML 55.1.
6. Choose lubricants with advanced technology
Not all lubricants are equal in their ability to extend lubrication intervals. Lubricants with MicPol® technology form a durably bonded barrier film that remains functional longer than conventional greases, even under variable loads, moisture, and contamination.
What is MicPol® technology?
MicPol stands for Micronized and Polarized. Micronized particles flatten microscopic surface peaks, reducing friction at the point of contact. Polarized particles bond chemically and mechanically to the metal and are not washed away by water or load.
The result: a homogeneous, water-repellent barrier that works at all speeds, protects during start-up and stop-start cycles, and is fully PFAS-free.
| Situation | Before | After |
|---|---|---|
| Apple processing facility | Weekly, components replaced each season | Once per season, zero downtime, 2-3x longer component life |
| Offshore crane - slewing bearing | Accelerated wear, high waste costs | 26.6% less lubricant, 75% less waste costs, 44,687 kg CO₂ saved |
| Poultry processing (Marel) | Weekly, 1,000 hrs/year, bearing failures | Fortnightly, 87% less grease, 950 hrs saved |
| Aggregate mining, Steengoed | 2-week interval, 3 grease types | 3-month interval, 1 grease type, 432 hrs saved |
When should I regrease? Practical guidelines
Five factors determine the lubrication interval.
- Temperature strongly affects grease life. For grease-lubricated bearings, SKF recommends halving the calculated relubrication interval for every 15°C increase above 70°C, within the grease’s temperature limits.
- Bearing speed is commonly expressed as the speed factor n × dm, where n is rotational speed and dm the mean bearing diameter. It is one of several factors affecting grease selection and relubrication intervals, alongside load, temperature and grease properties.
Lubrication regimes explained: from boundary to full film covers how film type affects lubrication interval. - Load and environment together accelerate lubricant film breakdown. Heavy radial loads, vibration, moisture, chemical aggression, and contamination all shorten the interval significantly.
- Condition monitoring, such as ultrasound, vibration analysis or temperature monitoring, can help optimise relubrication intervals where appropriate. The best method depends on the application and asset criticality.
- For electric motor bearings, open grease relief channels or drain plugs where specified by the manufacturer. This allows excess grease to escape and helps prevent over-lubrication and seal damage.
Conclusion
Many premature bearing failures can be prevented by treating lubrication as a controlled reliability process rather than a routine greasing task. Better lubricant selection, application, contamination control and interval management can reduce failures, maintenance interventions and downtime.
Lubricants represent only a small share of maintenance costs, while poor lubrication can have a much larger impact.
Want to know where the biggest opportunities are in your plant? Request a free lubrication analysis from an Interflon Technical Advisor or explore Lubrication as a Service (LaaS®).
Author: Janneke van der Pol, MLT1
Reviewed by: Mika Römpötti, Technical Manager Interflon Finland
& Vincenzo Tais, Technical Director Interflon Italy
Frequently Asked Questions
The most common cause of bearing failure in industry is incorrect lubrication. This includes using too little lubricant, too much lubricant, the wrong lubricant type, or applying lubricant at the wrong interval. According to SKF, 36% of all premature bearing failures are directly related to poor lubrication, and a further 14% to contamination. Other major causes include poor mounting, responsible for 16%, and fatigue, responsible for 34%. A structured lubrication management plan helps reduce premature bearing failure, improve machine reliability, and extend bearing service life.
You know when to regrease a bearing by calculating a relubrication interval from bearing type and size, speed, load, operating temperature, grease selection and environmental conditions, together with OEM or bearing-manufacturer guidance. Condition-monitoring methods such as ultrasound can then help optimise the interval in suitable applications.
As an SKF adjustment guideline for grease-lubricated bearings, the calculated relubrication interval is typically halved for every 15°C increase in operating temperature above 70°C, up to the grease's applicable high-temperature limit.
For consistent bearing lubrication, each lubrication point should have a documented relubrication interval in a lubrication management plan.
The difference between over-lubrication and under-lubrication is that under-lubrication can result in insufficient lubricant film separation, increasing friction and wear, while excessive grease in a bearing can cause churning, higher operating temperatures and potentially leakage or seal problems. Both over-lubrication and under-lubrication can contribute to premature bearing failure.
To prevent lubrication-related bearing damage, the correct lubricant quantity should be defined for every lubrication point and applied consistently.
Lubrication intervals can be extended without reducing reliability only when the lubricant remains effective and the component remains adequately protected throughout the longer interval. Start with a documented baseline, select a lubricant suited to the operating conditions, and extend intervals gradually within applicable OEM and engineering constraints while monitoring the application.
Lubricants with MicPol® technology have shown real-world results in Interflon applications, including extending lubrication intervals from two weeks to three months while maintaining reliability.
MicPol® technology helps with bearing lubrication by creating a durable, water-repellent barrier film on the metal surface. MicPol® combines micronized particles that flatten microscopic surface peaks, polarized particles that bond to the metal, and polarized base oil that forms a bonding bridge. This technology reduces friction, supports longer lubrication intervals, and helps protect bearings against wear and moisture. MicPol® technology is PFAS-free.
