30 Questions
What type of load application can cause permanent deformation of the raceways in a ball bearing?
Load exceeding the elastic limits of the steel
What is the term used to describe the formation of measurable dents at each ball location in a bearing?
Brinelling
What is the purpose of the oil film in an operating bearing?
To reduce friction
What is the term used to describe the damage caused by ambient environmental vibrations in a bearing?
False Brinelling
What is the primary reason for the formation of brownish corrosion deposits around depressions in a bearing?
Wear caused by grinding corrosion oxide
What is the term used to describe the damage caused by high-energy impacts in a bearing?
High-Energy Impact Damage
What happens to the balls or rollers in a bearing when it operates with proper lubrication and at the right speed?
They lift off the raceway slightly
What occurs when a bearing is stopped and there is no EHD film?
There is metal-to-metal contact
What is the primary cause of spalling in bearings?
Cyclic loading
What is the result of spalling in bearings?
The bearing surface becomes pitted and cracked
What is the term for the wear and corrosion pattern that mimics brinelling?
False brinelling
What is the purpose of the EHD film in a bearing?
To protect and lubricate the bearing
What is the primary cause of galling in a bearing?
Metal-to-metal contact and welding action
What is the result of metal-to-metal contact in a bearing?
Galling and wear of the bearing surface
What happens when hard particles enter the bearing ringways?
The particles cause roughness of the ring and ball, leading to failure
What is the term used to describe the transfer of metal from one surface to another in a bearing?
Galling
What is the result of rolling fatigue in a bearing?
Flaking of the bearing material
What is the term used to describe the wear caused by fine dust particles in a bearing?
Wear due to lapping compound
What is the primary cause of rust and corrosion on bearing surfaces?
Water in the lubricant
What is the characteristic of electrical pitting on a roller bearing's inner ring?
Corrugation of the raceway surface
What is burnishing, and what is its effect on the bearing surface?
Smoothing of surface roughness, with no measurable wear
Where may electrical pitting occur on a tapered roller bearing?
At the middle of the rolling contact surfaces
What is the condition under which burnishing may occur?
During periods of marginal lubrication
What is the appearance of a bearing surface that has undergone burnishing?
Discoloured
What is the first step to take when performing maintenance on a bearing?
Refer to the maintenance manual for guidance
Why must bushes be measured with Precision Measuring Equipment?
To check for dimensional accuracy
What is the purpose of de-magnetising a bearing?
To remove ferrous particles from the bearing
What is the requirement for the cleaning facility?
Ventilation and fire equipment
What is not allowed in the cleaning area?
Eating or drinking
When must a bearing be de-magnetised?
At the latest prior to final cleaning
Study Notes
Bearing Defects
- Brinelling: False brinelling is caused by ambient vibration, resulting in brownish corrosion deposits around depressions, and can occur in brand-new bearings exposed to environmental vibrations for an extended period.
- Spalling: The breakdown of surfaces due to cyclic loading, resulting in fatigue of the metal at localised points, appearing as irregular pitting with cracked edges.
- Galling: Occurs when the rolling element of the bearing skids, resulting in metal-to-metal contact and the transfer of metal from or to either surface.
- Flaking: Small pieces of bearing material split off from the smooth surface of the raceway or rolling elements due to rolling fatigue, creating regions with a rough texture.
Additional Defects
- Wear: Caused by dirt and hard particles getting into the bearing ringways, causing roughness of the ring and ball, and eventually leading to failure.
- Rust and Corrosion: Pits on the surface of rings and rolling elements, caused by water in lubricant.
- Electrical Pitting: Corrugation of the raceway surface, applying to the roller bearings' inner ring.
- Burnishing: Smoothing of the original surface roughness in the bearing races, resulting from mechanical rolling over during normal running.
Bearing Inspection and Maintenance
- Inspecting Rolling Element Bearings: No attempt should be made to clean or remove grease from the bearing during inspection.
- Cleaning: Takes place in a clean and tidy facility, with no eating or drinking allowed, and personal protective equipment (PPE) must be used.
- De-magnetising: Bearings must be de-magnetised at the latest prior to final cleaning to remove ferrous particles attracted to the balls, rollers, or races.
This quiz covers the causes and effects of brinelling and vibration on ball bearings, including the signs of wear and corrosion. Learn about the damage that can occur during transportation and usage. Understand how to identify and prevent these issues in bearings.
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