False brinelling is caused by vibrations acting on the bearing while in a non-rotating state and may occur on new equipment which has been carelessly transported. The signs of this type of brinelling, as seen in the image to the right, are depressions and wear marks in the bearing raceway along the axial direction.
What is brinelling in metal?
Brinelling is described as indentations or marks in the metal racers of a rolling element bearing. It is named for the Brinell scale of hardness.
What is true and false Brinelling?
True brinelling indicates that the load on the bearing is greater than the elastic limit of the ring or bearing material. False brinelling looks similar to true brinelling, but occurs through vibration, not necessarily excessive load.
What does false Brinelling look like?
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.
Which type of corrosion is known as false Brinelling?
False brinelling is a bearing damage caused by fretting, with or without corrosion, that causes imprints that look similar to brinelling, but are caused by a different mechanism. False brinelling may occur in bearings which act under small oscillations or vibrations.
What causes bearing fretting?
A type of frictional corrosion, fretting is caused by microscopic oscillating motions (vibrations) between the bearing surfaces. Because of these metallic particles, fretting is abrasive and will quickly worsen the symptoms of damage.
What type of corrosion has also been called false Brinelling?
5.12 Fretting corrosion Fretting corrosion may also be known as friction oxidation, wear oxidation, chafing, or false Brinelling (because of the appearance of pits similar to the indentations created in a Brinell hardness test).
What is bearing false Brinelling?
What causes fretting corrosion?
Fretting corrosion refers to corrosion damage at the asperities of contact surfaces. This damage is induced under load and in the presence of repeated relative surface motion, as induced for example by vibration. Contact surfaces exposed to vibration during transportation are exposed to the risk of fretting corrosion.
How do you prevent bearing fretting?
Countermeasures
- Use a proper lubricant.
- Apply a preload.
- Check the interference fit.
- Apply a film of lubricant to the fitting surface.
What is the difference between brinelling and ferretting?
Fretting is wear damage that is caused by metal to metal contact, under load and experiencing repetitive surface motion (vibration.) Under high magnification a false brinelling mark appears like small scratches. Pic 3: False brinelling looks more like particle scratching.
What is “fretting corrosion?
Fretting is a subtype of the “Corrosion” mode of damage/failure, and is often referred to as “fretting corrosion” because it produces fine, metallic particles that can oxidize, like rust. Because of these metallic particles, fretting is abrasive and will quickly worsen the symptoms of damage.
What is false brinelling and what causes it?
It is typically caused by vibrations that occur when the bearing is in a static state, and therefore the depressions caused by false brinelling will have the same spacing as the rolling elements.
How does false brinelling affect rolling element bearing performance?
Figure 3 shows a schematic and a photo- graph of typical false brinelling of a tapered rolling element bearing raceway. False brinelling causes noisy and, in some cases, inhibiting performance. It can also reduce rolling element bearing life by creating stress raisers leading to fatigue failure.
