This paper introduces the main factors leading to bearing failure and how to prevent the problem. By learning more about these potential problems and understanding how to prevent them, you can maximize the service life of your bearings.

1. Lubrication failure

According to a recent study, up to 80% of bearing failures are caused by improper lubrication. This includes inadequate lubrication, improper use of lubricants, or excessive temperatures that cause lubricant degradation.

Features: Check for discolored rolling elements (such as blue or brown) and rolling tracks and bearings for overheating or excessive wear.

Prevention: Use the appropriate type and correct amount of lubricant, avoid grease loss, and follow the appropriate refill lubrication intervals.

2. Pollution

Contamination is caused by foreign matter entering the bearing lubricant or cleaning solution. These include dirt, abrasives, dust, steel shavings, and dirty hands or tools from contaminated work areas.

Features: Note whether the rolling elements and raceways have dents that cause vibration.

Prevention: Filter lubricants and clean work areas, tools, fixtures and hands to reduce the risk of contamination.

3. Improper installation

In most cases, bearings should be mounted on the rotating ring by pressing fit.

Features: Many conditions can lead to bearing depression, wear, ring breakage, high operating temperatures, early fatigue and premature failure. These include mounting the bearing on the shaft by applying pressure or percussion to the outer ring, mounting the bearing into the housing by pressing the inner ring, loose shaft fit, loose housing fit, over-tight fit, irregular housing, and poor finish on the bearing housing.

Prevention: Follow proper installation instructions to ensure that all employees understand the difference between proper and incorrect installation.

4. Misalignment

Crooked crankshafts, bearing mounting skew, unsuitable gaskets, and improper installation due to loose fit may result in misalignment.

Features: Attention should be paid to wear that is not parallel to the edge of the non-rotating ring raceway.

Prevention: Check the shaft and housing shoulder and housing for run-out and use precision-grade lock nuts.

5. False Brinell indentation

When the equipment is idle, the ball is worn and lubricated by rapid movement in the raceway. In addition, the lack of rotation of the bearing does not allow fresh lubricant to return to the position. Both of these conditions can lead to false Brinell indentation.

Features: You may see axial linear wear marks at the roll pitch, or no raised edges, rather than marks due to incorrect installation.

Prevention: Eliminate or absorb external vibrations that may cause the ball to move. In addition, be sure to use lubricants that contain anti-wear additives.

6. Corrosion

Moisture, acid, poor quality or decomposing grease, poor packaging, and condensation due to excessive temperature inversion can cause corrosion that can wear down the finished surfaces of ball and roller bearings.

Features: Check rolling elements, raceways, or retainers for red and brown stains or deposits, as well as increased vibration, increased radial clearance, or loss of preload after wear.

Prevention: Transfer corrosive liquids from the bearing area. Choose solid sealed bearings and consider external seals for particularly harsh environments. If you cannot avoid a corrosive environment, then using the appropriate bearing material (such as stainless steel) can help.

7. Electrical damage (groove)

Continuous passing of AC or direct current, even if the current is small, can cause electrical damage.

Features: On most of the raceway or covering the entire circumference of the raceway, brown marks parallel to the axis may be observed.

Prevention: Prevent current from flowing through bearings by grounding or using insulated bearings.

8. Fatigue (peeling)

Spalling is usually caused by overload, excessive preload, too tight inner ring fit, and bearing use beyond its calculated fatigue life.

Characteristics: Fatigue can be indicated by the breaking of the running surface and the subsequent removal of small, discrete material particles from the inner ring, outer ring, or rolling element. Spalling is gradual and will spread with continuous operation. It is always accompanied by a noticeable increase in vibration and noise.

Prevention: Replace bearings and/or consider a redesign to use bearings with higher calculated fatigue life, internal clearance, and appropriate shaft and housing recommendations.

9. Overheating

Overheating is usually caused by high operating temperature and improper lubrication. High temperatures can lead to grease loss (removal of oil), which reduces the efficiency of the lubricant. Under high temperature conditions, oxidation will cause the lubricating oil in the grease to be lost, leaving dry, hard shell impurities, which can jam the bearing. Higher temperatures also reduce the hardness of the metal, leading to early failure.

Features: Note any discoloration of rings, rollers and cages. In extreme cases, bearing components can become deformed. Higher temperatures can also degrade or destroy the lubricant.

Prevention: Thermal or overload control, adequate thermal paths, and supplemental cooling are the best options for mitigating overheating.

10. Heavy load

Applying excessive load to bearings is another common cause of failure.

Features: You may see rolling element wear paths, signs of overheating, and extensive fatigue areas.

Prevention: Reduce the load or consider a redesign with a larger bearing capacity.

11. Improper storage and handling

Improper storage can expose bearings to moisture and dust. Storing bearings at too high a temperature can also shorten the shelf life of the grease, so be sure to consult the grease manufacturer for storage specifications. Disposing of bearings by opening the box too early and ripping open the packaging may allow dust to enter and expose the bearings to corrosive elements.

Note humidity and temperature that may cause rust in the storage area.

Prevention: Store bearings in a dry place at room temperature. Be sure to cover the bearing when storing it to keep it clean and bring it to the installation site before unpacking.

12. Mismatches

When interference fit exceeds the radial clearance at operating temperature, excessive load on the rolling element may result in over-tight fit. If the fit is too loose relative to the force, the slight movement between the fitting parts may cause the fit to loosen.

Characteristics: To achieve a tight fit, check the bottom of the raceway for severe rolling element wear paths, overheating, or axial cracks in the inner ring. For a loose fit, be aware of any wear (the production of fine metal particles), which will leave a distinctive brown color. Wear of the mating surface can cause noise and run-out problems.

Prevention: Make sure to choose the appropriate clearance to avoid fit problems. Refer to the manufacturer's installation guide.