When you are in trouble

1. At first

Damage to rolling bearings is not appropriate for the selection, environment, installation and maintenance, and there is a damage mode that loses function as a bearing.
When determining the cause of the damage to the bearing from the phenomenon at the time of this damage, it is very difficult to estimate the true cause often when the factor is various.
However, it is also possible to determine the cause by thoroughly understanding the terms of use and investigating the damage phenomenon.
Here, we post the damage case of the bearing, and we will show the main causes and measures, so we would like you to help us investigate the cause of the damage.

Reference standard JIS B 1652:2009 rolling bearings-damage and failure-terms, characteristics and causes

2. Classification of rolling bearing damage modes

Fig.1 shows the damage of rolling bearings divided into seven damage modes by cause.
On page 3, we show damage cases and their causes and countermeasures by damage mode. In addition, we will post the matrix of damage in Table 1.

3. Damage mode

3.1 Fatigue (flaking) (microcracks; spauling or pitching)

Fatigue is a change in material tissue caused by repeated stress esseon in the contact between the rolling body and the trajectory. Fatigue appears as a minute flaking from the surface (spauling or pitching).

Phenomenon	When the bearing rotates under load, the phenomenon of the rolling surface of the inner ring and outer ring trajectory surface or ball peels off in a scale by rolling tiredness
Cause	Excessive load, pre-pressure overload Poor mounting (misalignment) Moisture infiltration Foreign matter mixed Poor lubrication
Measures	Load reduction, bearing reselection Securing free side bearings Optimization of space and assembly Improving sealing equipment Lubricant reselection Review of refueling intervals

Phenomenon: Occurred on the circumference at the end of the orbital plane

Cause: Excessive load, pre-pressure overload, poor mounting (misalignment)

Phenomenon: Occurs at ball pitch spacing at the end of the track surface

Cause: Pressure due to impact load or poor installation (misalignment) during assembly

Phenomenon: Occurs at ball pitch spacing in the center of the track surface

Cause: Rust due to internal condensation or moisture infiltration

Phenomenon: Microcracks (spauling or pitching) occur in the ball running marks in the center of the track surface

Cause: Early material rolling tired

3.2 Wear

The wear, two slip contact surface or, the interaction of irregularities of the surface of the rolling / slip contact surface, the phenomenon of the material is gradually removed.

3.2.1 Abresive Wear

Phenomenon	Wear phenomenon in which the surface gradually dulls and eventually accelerates as the material is worn from the rolling surface and retainer
Cause	Foreign matter mixed Poor lubrication
Measures	Improving sealing equipment Lubricant reselection Review of refueling intervals

Phenomenon: The entire orbital surface is dull and wear-worn

Cause: Dust that has penetrated into the inside of the bearing

Photo2-1 Ball

Phenomenon: The entire surface of the ball is dull and worn

Phenomenon: Dullness occurs on the circumference at the end of the orbital surface

Cause: Poor lubrication due to poor installation (misalignment)

Phenomenon: Dull and wear-generated throughout the orbital surface

Cause: Sludge penetrated inside

3.2.2 Pseudo Brinell pressure (vibration corrosion)

Phenomenon	A phenomenon in which corrosion and wear occur while forming a depression in the contact area between the ball and the orbital surface due to periodic vibrations
Cause	Small swing movement Poor lubrication
Measures	Lubricant reselection Review of refueling intervals Review of swing width

Remarks Pseudo brinell indentation may be classified as corrosion.

Phenomenon: Local dent (wear) occurs at ball pitch spacing

Cause: Poor lubrication due to small-width swinging motion

Phenomenon: The ball running marks on the track surface are worn in a scale

Cause: Poor lubrication due to periodic vibration slower speed

Phenomenon: The ball running marks on the track surface meander, causing wear in a scale

Cause: Poor lubrication due to periodic vibration slower speed

Phenomenon: The ball running marks on the track surface are brown and discolored, causing wear in a scale

Cause: Poor lubrication due to periodic vibration in high-speed operation

3.3 Corrosion

Corrosion is a phenomenon in which a metal material reacts with a chemical reaction with a material in the surrounding environment (such as adjacent metals and gases), melts, or produces corrosion products (rust).

3.3.1 Moisture corrosion

Phenomenon	The phenomenon of surface oxidation by the moisture in the lubricant or in the air reacts with the bearing part
Cause	Poor storage condition Long-term stop in high temperature and humid environment Moisture (solvent) infiltration Lubricant inadequacy
Measures	Improving sealing equipment Improving storage methods and the environment Review of refueling intervals Lubricant reselection

Phenomenon: Surface oxidation (rust) occurs on bearing outer diameter

Cause: Inadequacy of condensation and storage condition in packaging containers

Phenomenon: Rust occurs at ball pitch spacing on the track surface

Cause: Insufficient condensation and storage condition inside bearings

Phenomenon: Rust occurs at ball pitch intervals during dulling of the track surface and stop driving

Cause: Moisture enters the inside of the bearing and lubrication is poor.

Phenomenon: Abnormal wear occurs while the orbital surface maintains gloss, causing local corrosion (rust) at the end of the track

Cause: Moisture (solvent) enters the inside of the bearing and poor lubrication

3.3.2 Frictional corrosion (fretting collider) (fretting rust)

Phenomenon	a phenomenon in which the two surfaces in contact (the overlapping surface) repeat relative to each other, resulting in a small slip and wear
Cause	Lack of tightening Excessive load Excessive vibration Motion of small width swinging
Measures	A review of The Shimora Review of the conclusion method Lubricant reselection Review of refueling intervals Reduced load/vibration

Phenomenon: Bearing outer diameter surface is oxidized (rusted) to cause wear

Cause: Action of excessive load and excessive vibration

Phenomenon: Oxidation (rust) occurs on the circumference of the bearing inner diameter surface

Cause: The effect of insufficient, excessive load, and excessive vibration

Phenomenon: The fit surface of the adapter exterior is oxidized (rusted) causing wear

Cause: Effect of insufficient tightening, excessive load, and excessive vibration

Phenomenon: The end of the stop screw is oxidized (rusted) causing wear

Cause: Lack of fastening of stop screws, action of excessive vibration

3.3.3 Stress corrosion cracking

Phenomenon	A material such as stainless steel is a phenomenon in which the interaction between tensile stress and corrosion environment causes cracks in the material and the cracks develop over time.
Cause	Action of water (chlorine), salt water, etc. Excessive fit Effect of tensile stress (stop screw tightening stress)
Measures	Improving sealing equipment Management of tightening torque of stop screws

Phenomenon: Cracks between the both screws on the stainless steel bearing

Cause: Action of chlorine-based cleaning agents and tightening of stop screws with excessive force

Photo 6-1 inner ring macro fracture surface

Phenomenon: Cracks gradually progress from the inner inner diameter of the stop screw side

Photo 6-1 inner ring micro-breaking surface

Phenomenon: Fracture surface with metal grain boundaries precipitated (grain boundary cracking)

Photo 6-1 inner ring microstructure

Phenomenon: The inner diameter surface is corroded locally, and cracks develop along the grain boundary.

3.4 Electric corrosion (electric fruiting)

The electrical eclipse is the lack of material from the contact surface caused by the current flowing.

Phenomenon	By the current flows through the lubricating oil film to the bearing, a phenomenon in which the contact area is melted with each other spark occurs at equal intervals on the contact surface of the ball and the track surface.
Cause	Lack of insulation Potential difference between outer ring and inner ring
Measures	Mounting of ground Change to ceraball bearing and insulate bearings Lubricant reselection Improvement of electrical circuits that do not flow current to bearings

Phenomenon: Burning of electrical fluting (sling pattern) at equal intervals on the outer ring track surface occurs

Cause: Insufficient insulation causes sparks in the contact area between the ball and the orbital surface.

Photo 7-1 Enlargement

Phenomenon: The material is missing (hollowed out) on the contact surface of the ball, and the hollow area is blackened.

Phenomenon: A thin burn of the electric fruiting pattern progresses to the outer ring track surface.

Cause: Spark in the contact area of the ball and the orbital surface with relatively weak current leakage strength

Photo 7-3 Inner ring

Phenomenon: A thin burn of the electric fruiting pattern progresses to the inner ring track surface, and it is blackened and discolored.

3.5 Plastic deformation

The plastic deformation, deformed by adding force to the object, permanent deformation that remains after removing the external force.
Permanent deformation occurs when the yield point of the material is exceeded, and there are two typical things

Macroscopic : A wide range of yields in the contact area due to the contact load between the rolling body and the trajectory
Microscopic : yield that occurs only in a narrow area of contact marks due to the biting (rolling) of foreign matter between the rolling body and the trajectory

3.5.1 Plastic deformation due to excessive load (brinel pressure)

Phenomenon	A phenomenon in which a shallow depression or groove of the ball pitch interval occurs in the track surface due to static or shocking overload load on a stationary bearing.
Cause	Poor built-in Pre-pressure overload Excessive load Impact load
Measures	Improved built-in methods Review of load conditions

Phenomenon: Pressure (dent) by the ball occurs at ball pitch spacing at the end of the inner ring track surface

Cause: Poor built-in or over-pressure

Photo 8-1 Outer ring

Phenomenon: Pressure (dent) by the ball occurs at ball pitch spacing at the end of the outer ring track surface

Phenomenon: A pressure (dent) by the ball occurs in the center of the inner ring track surface.

Cause: Excessive or impact loads

Photo 8-3 Outer ring

Phenomenon: A pressure (dent) by the ball occurs in the center of the outer ring track surface.

3.5.2 Pressure due to foreign matter

Phenomenon	a phenomenon in which foreign matter is rolled between the track surface and the ball causes a small depression
Cause	Foreign matter intrusion of metal powder, dust, etc. Biting of wear powder
Measures	Improving sealing equipment Review of refueling intervals

Phenomenon: Countless irregularities occur in the ball running marks on the track surface

Cause: Invasion of dust and foreign matter

Photo 9-1 Enlargement

Phenomenon: Dust and foreign matter bite and dent occur on the orbital surface

Photo 9-1 Ball

Phenomenon: The entire surface of the ball is dented by the biting of foreign matter.

Phenomenon: Countless small dents occur in the ball running marks at the end of the track surface

Cause: Internal wear powder bites due to increased rolling friction inside the bearing

3.6 Destruction and cracks

Cracks occur when the maximum tensile strength of the material is exceeded and propagated. Destruction is a complete separation of parts of a component that are propagated by cracks.

3.6.1 Forced destruction

Phenomenon	A phenomenon in which destruction occurs due to local stress concentration exceeding the tensile strength of the material due to excessive stress due to impact or excessive tightening.
Cause	Over-tightening Impact load Excessive load
Measures	Review of tightening conditions Improving load conditions

Phenomenon: Cracks in the axial direction from the inner ring screw hole

Cause: Tightening by excessive torque of the stop screw

Photo 10-1 Inner ring breaking surface

Phenomenon: The propagation pattern of the fracture surface progresses in the axial direction from the first thread of the screw hole.

Phenomenon: Cracks occur in a mortar shape from the inner ring screw hole, and the propagation pattern of the fracture surface develops radially from the screw hole to the outer diameter side.

Cause: Tightening by excessive torque of the stop screw

Phenomenon: Cracks in the axial direction from the inner diameter of the bearing inner ring with the adapter

Cause: Tightening with excessive torque of the adapter

3.6.2 Fatigue failure

Phenomenon	Bending generated in the track ring, ball and retainer, a phenomenon that cracks due to fatigue occurs when repeatedly exceeding the fatigue limit stress under tensile or torsionous conditions.
Cause	The Progress of Flaking Excessive axial load Poor lubrication
Measures	Improving load conditions Lubricant reselection Review of refueling intervals

Phenomenon: Flaking occurs on the outer ring track surface, destroying from the bottom of the track on the circumference

Cause: Development of flaking on the outer ring orbital surface

Phenomenon: Flaking occurs on the surface of the ball and destroys the hemisphere

Cause: Development of flaking on the surface of the ball

Phenomenon: Flaking occurs on the inner ring track surface of the adapterbearing and is destroyed in the axial direction.

Cause: Development of flaking on the inner ring orbital surface

Photo 11-3Inner ring breaking surface

Phenomenon: Cracks develop radially in the interior starting from the flaking portion of the inner ring orbit bottom

3.7 Seizure

Phenomenon	A phenomenon in which bearings generate heat during operation, resulting in discoloration, softening, welding of the track ring, ball and retainer leading to damage.
Cause	Poor lubrication Excessive load (pre-pressure overload) Excessive rotational speed Under-small internal space Invasion of moisture and foreign matter
Measures	Lubricant reselection Review of refueling intervals Review of load conditions Bearing reselection Review of internal space Improving sealing equipment

Phenomenon: Ball running marks at the end of the inner ring track surface are brown and discolored, causing flaking

Cause: Increased rolling friction due to pre-pressure overload

Phenomenon: Black charred grease adheres to the outer ring track surface

Cause: Poor lubrication due to heat

Phenomenon: The inner ring track surface is discolored to purple, causing significant roughness and wear

Cause: Poor lubrication due to dust intrusion into the inside of the bearing

Photo 12-3 Ball

Phenomenon: The ball surface is discolored to purple, and the surface is

表1 Matrix of Damage

Enlarging Matrix of DamageMatrix of Damage PDF

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