Common Causes of Bearing Failures and How to Prevent Them

Bearings are the vital, integral parts of many mechanic assemblies and take a primary toll on the efficiency and life of machines and machine tools. However, bearing assemblies are prone to various failure types, which may lead to high downtime and expensive repair procedures. There is a need to address the following fundamental pain points to improve the equipment’s reliability and ensure longer service life. Motors or bearings. The first focus will be on the bearing failure mechanics and the factors that lead to such failures: a lack of grease, the presence of foreign substances, and the mishandling of motor parts and bearings. In addition to identifying these problems, we seek to establish sound methods of averting them to promote the performance, lifespan, and reliability of the relevant equipment. The purpose of this guide is to help the audience understand, in detail, the underlying problems causing a failure of the bearing and, thereby, the steps to take to mitigate some of the risks associated with bearing failures during operations.

What are the Common Causes of Bearing Failure?

How does Improper Lubrication lead to failure?

Reading the top 3 websites on Google regarding the issues caused by improper lubrication can enhance understanding of bearing failure. A vital point is surfacing, which posits that the so-called bearing failures are mainly caused by one of three things: too little grease, too much grease, or the wrong type of grease. Too little grease means the lubricating material is barely performing its function, and as such, bearing surfaces suffer from higher levels of friction, leading to increased wear and tear. It usually results from improper maintenance training or maintenance schedules being postponed.

On the other hand, adding an excess of grease can produce heat forces on greases that lead to shear and turbulence that can break down lubricating oil. Extreme greases can also cause oil to escape the bearing houses. Losses of this nature not only lead to provisions of inadequate lubrication but also create chances of oil contamination that damages the bearings. Applying unsuitable grease, for instance, grease, which is inappropriate in terms of the temperature range or load conditions the application in question is likely to operate, can also lead to premature failure. Critical parameters that have to be observed include a temperature of the operation. This ensures that the operation temperature is suitable for the lubricant used. The other ones that must be controlled are the viscosity grade appropriate for the application and lubricating intervals that consider the bearing use environment and the size of the load on the bearing. Achieving these factors would assist in decreasing the chances of bearings getting damaged due to the misuse of the grease.

Can Misalignment cause bearing issues?

Yes, bearing failures are often due to misalignment. In this case, joints do not lie, so they have to carry more loads than intended. This increases vibrations and stress to the parts, resulting in faster deterioration. The significant causes of misalignment vary from improper assembly to geometry due to thermal contraction or expansion and deflection of the shaft. This misalignment causes excess axial or radial load on the bearing, decreasing the operating life and creating noise, higher operating temperature, and diffusing the lubricant.

Such technical parameters impacted by misalignment are the following:

Axial load(N): applied loads in a parallel plane totally to the shaft; this is unnecessary and should be efforts made to reduce it.

Radial load(N): The required load strength applied to the shaft must be distributed evenly for the shaft to operate effectively.

Vibration Parameters: An increase in vibration levels is a sign of an impending misalignment; too much vibration can worsen wear.

Temperature increase (°C): Alternatively, too much thermal expansion from the bearing destroys misalignment, which could lead to excessive lubrication and degradation of material quality.

However, if one goes ahead and tries to correct any misalignment, he can, in fact, mitigate the chances of bearing failure and increase the working life of the machine. Steps such as period inspection, using the correct application or installation, and aligning tools help to contain misalignment problems.

What role does Corrosion play in bearing failure?

Considering bearings, corrosion can be noted as a vital stress that precipitates bearing failure. Due to moisture or chemicals/contamination present in the environment/action of the bearing, metal surface corrosion occurs. This leads to the growth of rust and pitting, which affects the bearing’s ability to withstand the stresses of the design. Corrosion increases the degradation of the bearing surface, thereby making it less operational and attractive and increasing friction and wear, respectively. This, in turn, causes lower performance and shorter bearing life. The technical parameters influenced by corrosion include:

Surface Roughness: Corrosion causes increased surface roughness, increasing friction and wear.

Material Fatigue Limit: The lowered strength of the corroded surface consequently reduces the fatigue limit.

Lubrication Failure: The presence of corrosive materials may lead to lubricant failure, which in turn wears the bearing.

The probability of bearing failure due to corrosion can be reduced through regular inspection and the use of coatings or other corrosion-resistant materials. Proper seals and bearing lubrication procedures are also necessary so that bearings are not exposed to uncontrollable environments.

How Does Lubrication Affect Bearing Performance?

What is the impact of Lubrication Failure?

The role of lubricants, or the lack thereof, in bearing operations is one aspect that stands out. No bearing can be efficient without adequate lubrication as it helps to mitigate friction and wear. On the other hand, the lack of enough lubrication leads to increased friction on the bearings, which increases the temperature and speed of the bearings’ wearing. Furthermore, if a lubricant film is unavailable, metal contact happens, which damages the surface and leads to bearing failure. Some sources point out that the most critical technical parameters influence such as the following:

Friction Coefficient: An unlubricated surface tends to have a higher friction coefficient, which means it will require more energy to rotate the machine, leading to possible increases in temperature.

Temperature Rise (°C): Insufficient lubrication generates too much heat, which can alter the material’s properties and lead to failures at early stages.

Surface Wear Rate (µm/s): The thickness of the bearings is greatly reduced due to the wear and tear caused by moving parts in contact with each other without any sort of lubrication.

Load Capacity (N): No experience is required to know that lubrication contributes significantly to the structural integrity of the load-bearing surfaces.

Choosing the correct lubricant, lubrication intervals, and proper grease application can avoid these adverse effects, thus maintaining bearing performance and service life.

Which Lubricants are best for bearings?

Proper selection of lubricants for bearings is fundamental in ensuring both efficiency and durability. After consulting the best sources available, the following lubricants can be recommended:

Synthetic Oils: Synthetic oils’ apparent advantages include their ability to operate well within a wide range of temperatures and their enhanced thermal stability, making them extremely useful for bearing lubrication. They lower the friction coefficient and oxidation likelihood, which results in fewer deposits building up and increased bearing life.

Grease Lubrication: Grease is made of thickener and oil and covers surfaces with a consistent lubricant film to minimize friction. This is particularly advantageous in scenarios where easy access to the machinery for regular maintenance is cumbersome. Grease assists in excluding contaminants, which is essential to minimize surface wear rate.

Lithium Complex Grease: Lithium complex grease performs exceptionally well in harsh environmental conditions because it provides an effective lubricating layer, adheres well to metal substrates, and is also distinguished by its extremely strong water resistance. Due to its elevated level of Shear stability, it successfully regulates load capacity efficiently.

A contradiction coefficient, a temperature limit, and surface wear interact with these types of lubricants; all these factors should be considered in the intended application to ensure that the considered lubricant performs as planned regarding the mechanical stresses that may be encountered. The proper selection and application of these lubricants and the greases can assist in the effective maintenance of bearings and consequently improve the efficiency of the machines.

How can Improper Lubrication be avoided?

To prevent the effects of inappropriate lubrication, it is necessary to incorporate the best industry practices consistently. Below are the essential practices that can be found on leading websites:

Regular maintenance schedule: The strategy ensures that the average number of bearings receives the right type and amount of lubricant at the right time. With this method in place, there will be no chances of over- or under-lubrication, which eventually leads to bearing failure.

Choose the correct lubricant: Selecting the wrong lubricant can be very costly. The load, temperature, and environment need to be scrutinized. In extreme conditions, use synthetic oils and lithium complex grease in high water exposure conditions, but keep an eye on parameters such as friction coefficient and shear stability.

Employ proper application techniques: Correct lubrication techniques can be accomplished automatically using automatic lubrication systems. Even in the best of situations, human error is reduced, and contaminants are kept at a distance, thus averting excessive wear.

There is no universality in liquidity parameters either; all of them must be measured and substantiated in consideration of the requirement of the machine and operating range of temperatures, the limits of which are defined by the need of the operations howe of the machinery. These principles make the lubrication practices efficient, resulting in improved equipment reliability and efficiency of operational processes.

Why Do Bearings Fail Prematurely?

What are the signs of Premature Bearing Failure?

I use a few authorities in the field to look for specific signs of premature bearing failure. The following signs are mentioned in the latest ratings of the three highest sites that come up on Google search:

Abnormal Noise: Many times, loud sounds such as grinding, squealing, and banging indicate that the bearing is failing. Such noises are a good indication of some physical damage or failure of lubrication.

Increased Vibration: In machines, an elevated level of oscillation could indicate a misalignment, wear, or even imbalance in the radial bearing. Vibration analysis and other tools are necessary for early diagnosis.

Excessive Heat: The cause of excessive heating effect caused by bearings is primarily due to over-lubrication, frictional wear, and sometimes, improper loading. Also, studying the thermal performance of materials improves the understanding of the relative temperature of the disturbances.

Technical parameters such as measuring vibration frequency, determining the operating temperature norm, and making sound diagnoses still corroborate these observations. All signs must have a strictly defined diagnostic significance and correspond with the specification of the machine to which they are applied.

How does Overload contribute to early failure?

As for the cause, overload is the preeminent factor in causing early failure of the bearing as it applies stress on a bearing surface and the structure above the design limitations. As per the first three web pages of the websites shown on Google, some of the significant causes of overload are:

Bearings Operating Beyond Load Rating: Parts with a load rating that is exceeded are exposed to higher stresses, which in turn accelerate wear and tear and significantly increase the mantle stress, resulting in fractures and deformations in the bearing material.

Loss of Bearing’s Fatigue Life: As already known, an overload condition increases the bearing’s fatigue life due to high steady-state chronic stress, where micro-cracking damage and surface wearing processes are rapidly done. As a result, jerked cycles are likely to occur much less often than once a standard cycle.

Physical Changes: Excess bearing load may lead the bearing to some degree of physical change and even fracture, which is more likely when the load is applied suddenly or inhomogeneously. Such changes may prevent any bearing from operating properly because of the need for precise alignment.

Technical Note: Overload parameters also include the analysis of load distribution, i.e., how loads are distributed on the surfaces of the bearing outer and inner race and surfaces of the rolling elements of the bearing, and stress tests that determine the breaking load of a bearing. These parameters should be similar to the values in the characteristics of the bearing underdiagnosis so that appropriate measures can be undertaken in advance.

Is Vibration a critical factor in premature failure?

Yes, vibration is one of the factors that can result in the early failure of a bearing. Internal factors such as improper alignment, imbalance, looseness, or wear within the machine may result in excessive vibrations. A bearing with high vibration levels would have high contact forces between its rolling elements and raceways, leading to increased wear and the likelihood of the bearing failing. Some critical technical parameters that should be regularly monitored include:

Vibration Amplitude and Frequency: Such parameters can be measured by devices such as sensors and vibration analysis tools, which can detect imbalance or misalignment.

Overall Vibration Level: Increased M at any level can signify probable fault, including failure, and routine checks can be useful in predicting faults and making necessary corrections.

Frequency Spectrum Analysis: The above characteristic frequencies, together with other relevant information, help determine what type of bearing faults occur.

In diagnosing some of these conditions, the parameters are measured and interpreted appropriately, which helps extend the fatigue life of bearings and other parts.

How to Prevent Bearing Failures?

What are the best practices for Proper Bearing Mounting?

Appropriate bearing mounting is critical for effectiveness and longevity. There are several best practices recommended by top resources such as SKF, Timken, and NSK:

Cleanliness. The working area and tools are essential in the bearing assembly process. Dirt and other contaminants in the bearing assembly can lead to abrasion and early failure.

Correct Tools and Methods. Use appropriate tools, such as press fit, bearing heater, or fixtures. Hammers and other crude methods should not be used. Epicyclic mounting tools, especially bootstrap periodically, can be applied to achieve uniform pressure during installation.

Check Alignment. Ensure that the alignment during installation is accurate to avoid stresses and misalignments that may cause excessive vibration in the system. Manufacturer shaft and housing tolerances should also be observed.

Temperature Control. Ensure proper warmth is given to the bearings before mounting so that high forces are not required during installation. Induction heating devices suit this purpose because the temperature can be easily controlled.

Noise Indicators. After fitting the bearings, listen for abnormal sounds. If they indicate misalignment or failure to fit properly, ultrasound equipment can check for this.

Lubrication. Use the lubricant in the volume and type provided and recommended by the bearing maker. Failure to meet the correct volume may lead to over or under-lubrication, adversely affecting the bearing’s operation.

Implementing these measures creates solid grounds for significantly lowering the risk of bearing malfunction. The previously mentioned parameters also allow observing the proper mounting of the bearings, ensuring their efficient and proper functioning.

How can Sealed Bearings help in prevention?

Sealed bearings may significantly assist in reducing the failure rate of bearings as they provide an additional layer of armor against contamination from dirt, dust, and moisture. It is apparent from the leading sources on Google’s top results that sealed bearings are quite similar to closed bearings in that they are pre-lubricated, and therefore, improperly lubricated bearings are less prone to seal type. The seals do an excellent job of retaining lubricants and preventing the entry of contaminants, improving the bearing’s life and operational capability. Speaking of technical parameters, sealed-type bearings offer ideal properties such as:

Contaminant Exclusion: The seals inhibit the entry of moisture and other dirt particles from the outside, which could be abrasive to the internal parts and cause wear and damage.

Pre-lubrication: These bearings are pre-lubricated at manufacturing facilities with appropriate lubrication, greatly lowering the chances of over or under-lubrication and giving them a high level of reliability.

Reduced Maintenance: Sealed bearings contain their own internal lubrication systems, so maintenance intervention is warranted less often, thus saving time and reducing downtime.

Simplified Installation: During the installation process, there is no longer a requirement for an external lubrication system, making it easier to make fewer mistakes regarding the application of lubricant.

Sealed bearings tackle and answer these key parameters, reducing the likelihood of failures and providing the best quality throughout the bearing’s lifespan.

Why is Regular Maintenance essential?

Sealed bearings are designed for minimum maintenance due to their sealed construction and lubrication, but people forget that wear and tear if left unattended, could still cause unexpected troubles. Regular inspections assist in detecting material loss and impending failure, which could otherwise culminate in enormous operational losses. The parameters, from a technical perspective, that warrant regular maintenance are as follows:

Inspection of the Hosted Seals: If the seals are not damaged, the chances of dirt getting into the bearing and affecting its chances of survival are reduced.

Verification of the Lubricant: Maturing of lubricant or its utilization may pass in case a unit is sealed. Institutions of regular maintenance facilitate searching for lubricants and replacing them when necessary.

Monitoring of Bearing Temperatures: High and low temperatures are typical in bearing applications; thus, the design for such usage warrants that monitoring of working temperature is done.

Sealed bearings will function effectively in the long run if these maintenance strategies are followed, owing to their improved dependability and maintenance.

What Types of Bearing Failures Occur?

What is False Brinelling, and how does it occur?

False brinelling describes the damage visible on the bearings’ raceways due to vibrations or oscillations when the bearings are not in motion. Three articles I read on Wikipedia, for instance, claim that this phenomenon is not due to material loss but surface material displacement. It typically occurs as external vibration is applied to a bearing, which results in minute movements, giving rise to tracks simulating brinelling marks. Such parameters can be related to the following technical aspects:

Load Conditions: First, it is imperative to know that not all external loads are static, oscillating, or small-amplitude, for such load conditions are the key impetus for false brinelling.

Vibration Frequency: If vibration frequency is not constant, false brinelling may develop at a faster rate, and hence, it’s vital to keep such rates in check to prevent damage.

Contact Pressure: Where the primary cause of such wear may be the contact pressure, optimum pressure distribution across the surface of the bearing must be maintained to minimize such risk.

If these parameters are appropriately addressed, false brinelling would have no adverse effects, and the bearings in use would have better service and reliability.

How does Electrical Damage affect bearings?

EDM or bearings electrical damage is remelting and pit-forming on the raceways and/or rolling elements of a bearing. This condition is brought about by a bearing that carries an electric current. It is observed from the top three sites available on Google that this type of impairment results from the lack of proper insulation in the machines or improper solid engineering, which leaves the currents looking for routes through the bearings. The effect of electrical damage presents itself in the raceway with a fluted appearance and the bearings failing much earlier than expected. In workplaces where such situations cannot be ignored, the following technical parameters must be controlled:

Bearing Insulation: The current should not be able to flow around bearings where the current flow is meant to be restricted by appropriate insulating materials.

Earthing: Plenty of electric currents will need to be focused away from the bearings, so a proper earthing system will be needed.

Electric Voltage Load and its Time Pattern: Limitations must be set on the electric voltage load and its time pattern since any increase in such limits increases the chances of experiencing electrical damage.

Implementing these measures can significantly reduce electrical damage, preserving the functionality and life span of the bearings.

What are Raceway damages and their causes?

In evaluating the raceway damages, I noted that it’s almost always the case of surface degradation or even the complete wear down of the raceway elements of the bearing. Analysis of the best sources from around the world suggests the major raceway damage factors to be contamination, poor lubrication, lousy installation and design, and excessive loads. Dirt contamination is described as introducing hard particles, which would cause indentations and scraping of the raceways. In contrast, weak lubrication causes heating and grinding as these components would be in increased friction. There may also be improper installation where the paths of the raceways are not placed in the correct direction, leading to uneven loads. There is also the case of excessive loads, which are unexpected by the raceway surface, thus causing a fast breakdown and stress of fatigue. Regarding these technical factors, there is a need to control the following:

Contamination Control: Installing efficient sealing systems to stop ingress dust particles and use clean facilities to assemble the components.

Lubrication Control: Using the correct lubricant and maintaining sufficient lubricant.

Correct Method of Installation: Carefully follow the installation procedures while ensuring the proper alignment.

Load Control: Constructing machines and structures with appropriate load distribution and bearing load limits.

With these measures, raceway damage can be reduced, which optimally improves performance and bearing life since raceway damage is one of the crucial parameters in this context.

Frequently Asked Questions (FAQs)

Q: What problems are most likely to lead to bearings failing?

A: Bearing failures can be caused by a number of typical causes, such as poor lubrication, contamination, heat, misalignment, and abusive handling. These causes tend to create excess friction, wear bearing parts, and compress bearing life.

Q: What factors cause bearing damages as a result of lubrication?

A: Bearing failure may be associated with lubrication problems if the grease or oil relative to volume, contamination, and suitability to the relevant operating environment is inappropriately supplied. Bearing lubricants are crucial in reducing friction and bearing wear; therefore, the bearing surface must be properly lubricated to prevent damage and failure.

Q: What are the bearing life implications when the components are misaligned?

A: Misalignment will cause the bearing’s parts to have uneven wear patterns due to excessive load and vibration, accelerating wear. Bent shafts and placing cartoon mounts all lead to misalignment, and these conditions can lower the bearing’s service life.

Q: Is there any reason why the wrong material should not be used to construct the bearings?

A: The bearing’s ability to withstand extreme temperatures, loads, or environmental conditions will depend on the material used to make it. Inappropriate material will also ensure the bearing components’ high wear-out and failure rate.

Q: What are the possible effects of high temperatures working on the bearings?

A: High operating temperatures harm the grease/oil lubricating the bearing by degrading it, leading to high friction and wear. Elevated temperatures may also cause changes in the properties of the bearing materials, reducing the bearing’s fatigue life in the long run.

Q: How important is the preload in bearing operation?

A: Preload is defined as applying a constant axial load to a bearing so that internal clearance is eliminated. A controlled amount of preload may improve performance by decreasing vibration and enhancing load distribution. On the other hand, excessive preload increases friction, which will reduce the bearing’s lifespan.

Q: What are the causes of bearing failures due to pollution?

A: Detrimental pollutants such as dirt, dust, and moisture can encroach on the bearing, promoting corrosion, wear, and increased friction. A clean work environment and the application of seals may assist in limiting the acceptance of pollutants on the bearing surfaces.

Q: What are the characteristics of organizations whose raceways have been impaired based on bearing raceways?

A: Impairment of bearing raceways can be determined by visual wear paths, surface pitting, grooves on the inner ring, and so on, all occurring on different raceways. Such damage is due to improper lubrication, foreign materials, and extreme loads, failing such bearings.

Q: In what ways can SKF assist in averting the occurrences of bearing failures?

A: SKF’s provision of roller bearings of the highest standards, lock nuts of the highest precision, and advanced bearing lubricants encompass a wide range of solutions to help prevent bearing failures. Their bearing industry knowledge in this area fosters fruitful failure analysis and the proper bearing selection for particular needs.