ZNL Bearings - a Precision Bearings Pvt. Ltd. Product

In general, if rolling bearings are used correctly, they will survive to their predicted fatigue life. Bearings, however, often fail prematurely due to avoidable mistakes. The causes of, this premature failure include improper mounting, mishandling, poor lubrication, entry of foreign matter or abnormal heat generation All the various causes and the prevention required for that cause areas mentioned below:

Flaking occurs when small pieces of bearing material are split off from the smooth surface of the raceway or rolling elements due to rolling fatigue, thereby creating regions having rough and coarse texture.

Causes
Excessive load; Poor mounting (misalignment); Entry of foreign debris, water penetration; Poor lubrication, Unsuitable bearing clearance; Improper precision for shaft or housing, large shaft bending; Rust, corrosion pits, Smearing, dents (brinelling)

Preventive measures

Reconfirm the bearing application and check the load conditions
Improve mounting method
Improve the sealing mechanism, prevent rusting during non-running
Use a lubricant with a proper viscosity, improve the lubrication method
Check the precision of shaft and housing
Check the bearing internal clearance

Dull spots BlindDown on surface along with light Wear. From such dull spots, tiny Cracks are generated downward to a depth of 5-10 µm.

Causes
Unsuitable lubricant
Entry of debris into lubrication
Rough surface due to poor lubrication
Surface roughness of mating rolling parts

Preventive measures

Select a proper lubricant
Improve the sealing mechanism
Improve the surface finish of the rolling mating parts

Scoring is surface damage due to accumulated small seizures caused by sliding under improper lubrication or severe operating conditions. Linear damage BlindDowns circumferentially on the raceway and roller surfaces. Cycloidal shaped damage on the roller ends and Scoring on the rib surface contacting roller ends also occur.

Causes
Excessive load, excessive preload
Poor lubrication
Particles are caught in the surface
Inclination of inner and outer rings
Shaft bending
Poor precision of the shaft and housing

Preventive measures

Check the magnitude of the load
Adjust the preload
Improve the lubricant and the lubrication method
Check the precision of the shaft and housing

Smearing is surface damage which occurs from a collection of small seizures between bearing components caused by oil film rupture and/or sliding.

Causes
High speed and light load
Sudden acceleration/deceleration
Improper lubricant
Entry of water

Preventive measures

Improve the bearing clearance
Use a lubricant with good oil film formation ability
Improve the sealing mechanism

Fracture refers to small pieces which were broken off due to excessive load or shock load acting locally on a roller corner or rib of a raceway ring

Causes
Impact during mounting
Excessive load

Preventive measures

Improve the mounting method (shrink fit, use of proper tools)
Reconsider the load conditions
Provide enough back-up and support for the bearing rib

Cracks in the raceway ring and rolling elements. Continued use under this condition leads to larger Cracks or Fractures.

Causes
Excessive interference
Excessive load, shock load
Progression of Flaking
Heat generation and Fretting caused by contact between mounting parts and raceway ring
Heat generation due to Creep
Poor taper angle of tapered shaft
Poor cylindricality of shaft
Interference with bearing chamfer due to a large shaft corner radius

Preventive measures

Correct the interference
Check the load conditions
Improve the mounting method

Cage damage includes:
Cage deformation, Fracture and Wear Fracture of cage pillars
Deformation of side face
Wear of pocket surface
Wear of guide surface

Causes
Improper mounting (Bearing misalignment)
Large moment load
Shock and large vibration
Excessive rotation speed, sudden acceleration and deceleration
Poor lubrication
Temperature rise

Preventive measures

Check the mounting method
Check the temperature, rotation and load conditions
Reduce the vibration
Use an appropriate shaft shape Select a different cage type
Select a different lubrication method and/or lubricant

When debris such as small metallic particles are caught in the rolling contact zone, denting occurs on the raceway surface or rolling element surface.

Causes
Debris such as metallic particles are caught in the surface
Excessive load
Shock during mounting

Preventive measures

Clean the housing
Improve the sealing mechanism
Filter the lubrication oil
Improve the mounting and handling methods

Pitting has a dull luster and BlindDowns on the rolling element surface or raceway surface

Causes
Debris becomes caught in the lubricant
Exposure to moisture in Poor lubrication

Preventive measures

Improve the sealing mechanism
Filter the lubrication oil thoroughly
Use a proper lubricant

Wear is surface deterioration due to sliding friction at the surface of the raceway, rolling elements, roller end faces, rib face, cage pockets, etc.

Causes
Entry of debris
Progression from rust and electrical corrosion
Poor lubrication
Sliding due to irregular motion of rolling elements

Preventive measures

Improve the sealing mechanism
Clean the housing
Filter the lubrication oil thoroughly
Check the lubricant and lubrication method
Prevent misalignment

Wear occurs due to repeated sliding between the two surfaces.

Causes
Poor lubrication
Vibration with a small amplitude
insufficient interference

Preventive measures

Use a proper lubricant
Apply a preload
Check the interference fit
Apply a film of lubricant to the fitting surface

Among the different types of Fretting, false brinelling is the occurrence of hollow spots that resemble brinell dents and are due to Wear caused by vibration and swaying at the contact points between the rolling elements and raceway

Causes
Oscillation and vibration of a stationary bearing during such times as transporting
Oscillating motion with a small amplitude
Poor lubrication

Preventive measures

Transport with the inner and outer rings packed separately
Reduce the vibration by preloading
Use a proper lubricant

Creep is the phenomenon in bearings where relative slippage occurs between fitting surfaces and thereby creates a clearance between them surface. Creep causes a shiny BlindDownance, occasionally with Scoring or Wear.

Causes
Insufficient interference or loose fit
Insufficient sleeve tightening

Preventive measures

Check the interference and prevent rotation
Correct the sleeve tightening
Study the shaft and housing precision
Preload in the axial direction
Tighten the raceway ring side face

When sudden overheating occurs during rotation, the bearing becomes discolored. Then, the raceway rings, rolling elements, and cage will soften, melt and deform as damage accumulates

Causes
Poor lubrication
Excessive load (Excessive preload)
Excessive rotational speed
Excessively small internal clearance
Entry of water and debris
Poor precision of shaft and housing Excessive shaft bending

Preventive measures

Study the lubricant and lubrication method
Reinvestigate the suitability of the bearing type selected
Study bearing clearance and fitting
Improve the sealing mechanism
Check the precision of the shaft and housing
Improve the mounting method

Bearing rust and corrosion are pits on the surface of rings and rolling elements and may occur at the rolling element pitch on the rings or over the entire bearing surfaces.

Causes
Entry of corrosive gas or water
Improper lubricant
Formation of water droplets due to condensation of moisture
High temperature and high humidity while stationary
Poor rust-preventive treatment during transporting
Improper storage conditions
Improper handling

Preventive measures

Improve the sealing mechanism
Study the lubrication method
Anti-rust treatment during periods of non-running
Improve the storage methods
Improve the handling method

Straight line scratches on surface of raceways or rolling elements caused during mounting or dismounting of bearing

Causes
Inclination of inner and outer rings during mounting or dismounting
Shock load during mounting or dismounting

Preventive measures

Avoid shock loads by using a press machine
Center the relative mating parts during mounting

Discoloration of cages, rolling elements and raceway rings occurs due to their reacting with lubricant at high temperature

Causes

Poor lubrication
Oil stain due to a reaction with lubricant
High temperature

Preventive measures

Improve the lubrication method

Flaking

Peeling

Scoring

Smearing

Fracture

Cracks

Cage Damage

Denting

Pitting

Wear

Fretting

False Brinelling

Creep

Seizure

Rust And Corrosion

Mounting Flaws

Discoloration





Engineering & Service Maintenance

In general, if rolling bearings are used correctly, they will survive to their predicted fatigue life. Bearings, however, often fail prematurely due to avoidable mistakes. The causes of, this premature failure include improper mounting, mishandling, poor lubrication, entry of foreign matter or abnormal heat generation All the various causes and the prevention required for that cause areas mentioned below: Flaking occurs when small pieces of bearing material are split off from the smooth surface of the raceway or rolling elements due to rolling fatigue, thereby creating regions having rough and coarse texture. Causes Excessive load; Poor mounting (misalignment); Entry of foreign debris, water penetration; Poor lubrication, Unsuitable bearing clearance; Improper precision for shaft or housing, large shaft bending; Rust, corrosion pits, Smearing, dents (brinelling) Preventive measures Reconfirm the bearing application and check the load conditions Improve mounting method Improve the sealing mechanism, prevent rusting during non-running Use a lubricant with a proper viscosity, improve the lubrication method Check the precision of shaft and housing Check the bearing internal clearance Dull spots BlindDown on surface along with light Wear. From such dull spots, tiny Cracks are generated downward to a depth of 5-10 µm. Causes Unsuitable lubricant Entry of debris into lubrication Rough surface due to poor lubrication Surface roughness of mating rolling parts Preventive measures Select a proper lubricant Improve the sealing mechanism Improve the surface finish of the rolling mating parts Scoring is surface damage due to accumulated small seizures caused by sliding under improper lubrication or severe operating conditions. Linear damage BlindDowns circumferentially on the raceway and roller surfaces. Cycloidal shaped damage on the roller ends and Scoring on the rib surface contacting roller ends also occur. Causes Excessive load, excessive preload Poor lubrication Particles are caught in the surface Inclination of inner and outer rings Shaft bending Poor precision of the shaft and housing Preventive measures Check the magnitude of the load Adjust the preload Improve the lubricant and the lubrication method Check the precision of the shaft and housing Smearing is surface damage which occurs from a collection of small seizures between bearing components caused by oil film rupture and/or sliding. Causes High speed and light load Sudden acceleration/deceleration Improper lubricant Entry of water Preventive measures Improve the bearing clearance Use a lubricant with good oil film formation ability Improve the sealing mechanism Fracture refers to small pieces which were broken off due to excessive load or shock load acting locally on a roller corner or rib of a raceway ring Causes Impact during mounting Excessive load Preventive measures Improve the mounting method (shrink fit, use of proper tools) Reconsider the load conditions Provide enough back-up and support for the bearing rib Cracks in the raceway ring and rolling elements. Continued use under this condition leads to larger Cracks or Fractures. Causes Excessive interference Excessive load, shock load Progression of Flaking Heat generation and Fretting caused by contact between mounting parts and raceway ring Heat generation due to Creep Poor taper angle of tapered shaft Poor cylindricality of shaft Interference with bearing chamfer due to a large shaft corner radius Preventive measures Correct the interference Check the load conditions Improve the mounting method Cage damage includes: Cage deformation, Fracture and Wear Fracture of cage pillars Deformation of side face Wear of pocket surface Wear of guide surface Causes Improper mounting (Bearing misalignment) Large moment load Shock and large vibration Excessive rotation speed, sudden acceleration and deceleration Poor lubrication Temperature rise Preventive measures Check the mounting method Check the temperature, rotation and load conditions Reduce the vibration Use an appropriate shaft shape Select a different cage type Select a different lubrication method and/or lubricant When debris such as small metallic particles are caught in the rolling contact zone, denting occurs on the raceway surface or rolling element surface. Causes Debris such as metallic particles are caught in the surface Excessive load Shock during mounting Preventive measures Clean the housing Improve the sealing mechanism Filter the lubrication oil Improve the mounting and handling methods Pitting has a dull luster and BlindDowns on the rolling element surface or raceway surface Causes Debris becomes caught in the lubricant Exposure to moisture in Poor lubrication Preventive measures Improve the sealing mechanism Filter the lubrication oil thoroughly Use a proper lubricant Wear is surface deterioration due to sliding friction at the surface of the raceway, rolling elements, roller end faces, rib face, cage pockets, etc. Causes Entry of debris Progression from rust and electrical corrosion Poor lubrication Sliding due to irregular motion of rolling elements Preventive measures Improve the sealing mechanism Clean the housing Filter the lubrication oil thoroughly Check the lubricant and lubrication method Prevent misalignment Wear occurs due to repeated sliding between the two surfaces. Causes Poor lubrication Vibration with a small amplitude insufficient interference Preventive measures Use a proper lubricant Apply a preload Check the interference fit Apply a film of lubricant to the fitting surface Among the different types of Fretting, false brinelling is the occurrence of hollow spots that resemble brinell dents and are due to Wear caused by vibration and swaying at the contact points between the rolling elements and raceway Causes Oscillation and vibration of a stationary bearing during such times as transporting Oscillating motion with a small amplitude Poor lubrication Preventive measures Transport with the inner and outer rings packed separately Reduce the vibration by preloading Use a proper lubricant Creep is the phenomenon in bearings where relative slippage occurs between fitting surfaces and thereby creates a clearance between them surface. Creep causes a shiny BlindDownance, occasionally with Scoring or Wear. Causes Insufficient interference or loose fit Insufficient sleeve tightening Preventive measures Check the interference and prevent rotation Correct the sleeve tightening Study the shaft and housing precision Preload in the axial direction Tighten the raceway ring side face When sudden overheating occurs during rotation, the bearing becomes discolored. Then, the raceway rings, rolling elements, and cage will soften, melt and deform as damage accumulates Causes Poor lubrication Excessive load (Excessive preload) Excessive rotational speed Excessively small internal clearance Entry of water and debris Poor precision of shaft and housing Excessive shaft bending Preventive measures Study the lubricant and lubrication method Reinvestigate the suitability of the bearing type selected Study bearing clearance and fitting Improve the sealing mechanism Check the precision of the shaft and housing Improve the mounting method Bearing rust and corrosion are pits on the surface of rings and rolling elements and may occur at the rolling element pitch on the rings or over the entire bearing surfaces. Causes Entry of corrosive gas or water Improper lubricant Formation of water droplets due to condensation of moisture High temperature and high humidity while stationary Poor rust-preventive treatment during transporting Improper storage conditions Improper handling Preventive measures Improve the sealing mechanism Study the lubrication method Anti-rust treatment during periods of non-running Improve the storage methods Improve the handling method Straight line scratches on surface of raceways or rolling elements caused during mounting or dismounting of bearing Causes Inclination of inner and outer rings during mounting or dismounting Shock load during mounting or dismounting Preventive measures Avoid shock loads by using a press machine Center the relative mating parts during mounting Discoloration of cages, rolling elements and raceway rings occurs due to their reacting with lubricant at high temperature Causes Poor lubrication Oil stain due to a reaction with lubricant High temperature Preventive measures Improve the lubrication method Flaking Peeling Scoring Smearing Fracture Cracks Cage Damage Denting Pitting Wear Fretting False Brinelling Creep Seizure Rust And Corrosion Mounting Flaws Discoloration
Download Product Catalogue Homepage Profile Products Quality Engineering & Service Contact Enquiries Samples & Catalogue