S, a designer, and Ms. Can discussed a puzzling issue: despite selecting bearings with sufficient safety margins, many motors still failed due to bearing problems after being mass-produced and released to the market. Ms. Can reviewed the inspection records provided by S in detail and discovered that most failures were caused by dry friction in the bearings due to insufficient lubrication. Further verification of the tracking records revealed that the lubricating grease was not up to standard.
The above events demonstrate that the lifespan of motor bearings is far more complex than simply selecting models with sufficient margin; lubrication is a significant limiting factor. Furthermore, improper assembly, poor sealing, and overload fatigue are also major causes of premature bearing failure, thus shortening their actual lifespan. Bearing lifespan is crucial to ensuring the long-term safe operation of the motor's effective components, the stator and rotor.
Regarding bearing life
Rolling bearing life
Generally speaking, metal fatigue of rolling contact surfaces is the main cause of rolling bearing damage. The life of a rolling bearing is defined by the number of revolutions (or the number of working hours at a certain number of revolutions). Within this life, the bearing does not experience initial fatigue damage (sparging or defects) on any of its bearing rings or rolling surfaces.
Because bearings operating under the same conditions can have different actual lifespans, the more accurate definition of "rolling bearing life" is: the lifespan that 90% of a sufficiently large group of identical bearings should reach or exceed under rated load.
Calculate lifespan
The number of revolutions or hours calculated based on the load and revolutions utilization life formula.
Actual lifespan
This refers to the actual lifespan a bearing can achieve before it fails. Bearing failure is usually not caused by fatigue, but may be caused by factors such as incorrect selection, poor lubrication, contamination, or improper installation.
Extend bearing service life
Installation and removal
1) Use mechanical, hydraulic or heating methods to perform proper and effective bearing assembly.
2) Utilize a full range of tools and equipment for various professional engineering service technologies, making these tools simple, fast, and exponentially more effective.
3) Use specialized tools and techniques for professional assembly to maximize machine uptime.
lubricating
Although various "maintenance-free" sealed bearings can be installed, 35-36% of premature bearing failures are still caused by incorrect or improper application of grease. Any improperly lubricated bearing will inevitably fail before its normal service life.
Bearings are often the most difficult components to install and remove in mechanical equipment, and problems will arise if they are not lubricated regularly. In situations where manual maintenance is not feasible, a fully automated lubrication system can be developed to achieve optimal lubrication. Effective lubrication, provided that high-quality grease, tools, and techniques are used as required, will significantly reduce downtime.
pollution prevention
Bearings are precision components; if the bearings and grease become contaminated, they will not function effectively. Furthermore, since pre-lubricated, maintenance-free sealed bearings constitute only a small fraction of all bearings in use, at least 15% of all premature bearing failures are due to contamination issues.
Fatigue prevention
●Preventing machine overload, improper use or maintenance can affect bearings and cause them to fail prematurely.
● Use condition monitoring equipment for detection and analysis. When the bearing is improperly maintained or under excessive stress, it will issue an "early warning" to avoid sudden or unplanned failure.
Bearing Usage Precautions
Rolling bearings are a component of precision machinery and must be handled with utmost care. Otherwise, as Little S wondered, even high-performance bearings cannot achieve the desired results if used improperly.
Use bearings
(1) Keep the bearing and its surrounding area clean (dust must not get in).
(2) Use with care (avoid strong impacts).
(3) Use accurate tools (avoid using substitute tools).
(4) Take care to prevent the bearings from rusting (wear gloves to avoid sweaty hands. Beware of corrosive gases).
(5) In general, the shaft rotates most often. Therefore, the inner ring is an interference fit, and the outer ring of the bearing is a clearance fit with the bearing housing.
Assembly
The quality of bearing assembly will affect the bearing's precision, lifespan, and performance. Bearing assembly should be performed according to the following steps.
(1) Clean the bearings and related parts;
(2) Inspect the dimensions and finishing of the relevant parts;
(3) Assemble the bearings;
(4) Inspection after bearing installation;
(5) Add an appropriate amount of lubricant.
