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FAQ

Bearing is the machine element used in between rotating & sliding elements to minimise friction.

Ball Bearing

Roller Bearing

Plain Bearing

Angular Contact Ball Bearing

Deep Groove Ball Bearing

Four Point Contact Bearing

Magneto Ball Bearing

Miniature Ball Bearing

Self Aligning Ball Bearing

Thrust Ball Bearing

What are the types of Roller Bearing ?

  • Cylindrical Roller Bearing
  • Tapered Roller Bearing
  • Spherical Roller Bearing
  • Crossed Roller Bearing
  • Needle Roller Bearing
Bearing designation is the alphanumeric combinations that indicate the Bearing type, boundary dimensions, dimensional and running accuracies, internal clearance, and other related specifications. It consist of basic numbers and supplementary symbols.

The boundary dimensions of Rolling Bearings are the dimensions that define its external geometry. It includes bore diameter, outside diameter, width, bearing width (or height) and chamfer dimension, etc. It is necessary to know while mounting a bearing on a shaft or in a housing.

“Z” is a designation which means a steel shield covering the one side of the bearing (for most brands). “ZZ” means that the bearing has a shield on both sides.

Normally, the shield itself will be branded as “608 Z” even though there is a shield on both sides of the bearing. This is for practicality in manufacturing. It is much more economical to produce all the shields stamped as “608 Z” than it would be to manufacture the exact same component with two different stampings on them.

Shields or Seals are often installed to retain lubricant and to prevent contamination from entering into the Bearing. A shield contacts the outer ring and does not come in contact with the inner ring, whereas the seal generally comes in contact with both the inner and outer rings.
Torque or drag is lower with a shield than with a seal. Alternately, the seal provides a higher degree of protection from contamination. Shields and Seals are available in a variety of materials and configurations.

By use of a ‘Labyrinth Seal’

The Labyrinth Seal is a non-contact seal with special internal construction which centrifuges dirt back out to where it came.

Labyrinth seals are formed by interdigitated segments attached to the shaft & housing that are separated by a very small gap. They are particularly suitable for preventing oil leakage from the shaft at high speeds.

The retainer (also called cage or separator) is used to separate the balls and equally position them around the bearing raceway. Some retainer materials contain lubricant for extended bearing life.

Retainers for Ball Bearings are generally available in two designs. The most universal is a 2-Piece Closed Ball Pocket design called a ‘Ribbon Retainer.’ A Single Piece Open Ball Pocket design is called a ‘Crown Retainer.’ Crown Retainers are available in a variety of metal and nonmetal options. Phenolic Retainers are excellent options for high-speed applications.

Angular Contact Bearings are a non-separable type. The line connecting contact points of the steel ball and inner ring and the steel ball and outer ring create an angle with the line drawn in the radial direction called the contact angle. In addition to radial loads, relatively heavy axial loads in one direction can be accommodated by an angular contact bearing. The larger the contact angle, the larger the axial loading capacity becomes.
Deep Groove Ball Bearings are a non-separable type bearing with the line connecting contact points of the steel ball and inner ring and the steel ball and outer ring of 0º in the radial direction. They are designed to take mainly radial loads but can handle some axial load in either direction.
All application data (loads, speeds, orientation, etc.), intended use, and environment.
Back-to-Back (DB) or Face-to-Face (DF) are duplex arrangements of Angular Contact Bearings. Radial loads and axial loads in either direction can be accommodated by these arrangements. DB should be selected when shaft mounting rigidity is the primary factor. Select DF when shaft misalignment is a concern. The DB arrangement requires the inner rings to be clamped whereas the DF arrangement requires the outer rings to be clamped.

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It is the combined clearance between the inner/outer rings and rolling elements. The radial and axial clearances are defined as the total amount that one ring can be displaced relative to the other in the radial and axial directions respectively.

Precision grade only tells us how close the bearing dimensional tolerances are (that is, how close the bearing is to the stated size).

Lowest to Highest

  • ABEC 1 = ISO P0
  • ABEC 3 = ISO P6
  • ABEC 5 = ISO P5
  • ABEC 7 = ISO P4
  • ABEC 9 = ISO P2
ABEC is an acronym for Annular Bearing Engineering Committee of the AFBMA (Anti-Friction Bearing Manufacturers Association Inc). The ABEC grades of bearings is a set of standards for the manufacturing tolerances of bearings.

The Annular Bearing Engineers Committee (ABEC) of the American Bearing Manufacturers Association (ABMA) establishes standards for manufacturing precision ball bearings. These standards are also accepted by American Standardization Institute (ANSI) and by international agreement for the standards developed by the International Standards Organization (ISO).

The ABEC and ISO bearing standards primarily define dimensions & tolerances for the bearings. These standards do not define many other aspects of the bearing such as lube, radial play, ball complement, retainer type, torque, cleanliness, etc.

Higher Precision Bearings are designed to allow high precision machinery to operate smoother and sometimes at higher speeds than a standard bearing would allow.
ABEC 3 is an AMBA tolerance class. C3 is an internal clearance specification. Fit is the relationship between the bearing bore and outside diameters to the housing bore and shaft outside diameter. Tolerance, Clearance and Fit are independent dimensions, although in some cases choosing a larger internal clearance can allow you to use a tighter interference fit.
Preload is an initial load or “Negative Clearance” given to a bearing before or during operation. This results in the rolling element and raceway surfaces being under constant elastic compressive forces at their contact points. This has the effect of making the bearing extremely rigid so that even when load is applied to the bearing, radial or axial shaft displacement is minimized.
  1. To maintain the bearings in exact position both radially and axially and to maintain the running accuracy of the shaft.
  2. To increase bearing rigidity.
  3. To minimise noise due to axial vibration and resonance.
  4. To prevent sliding between the rolling elements and raceways due to gyroscpic moments.
  5. To maintain the rolling elements in their proper position with the bearing rings.
Rolling bearings are high-precision machine parts, they must be handled accordingly. Even if high-quality bearings are used, their expected performance cannot be achieved if they are not handled properly.
  • Keep Bearings and Surrounding Area Clean (to prevent the entry of dust and dirt)
  • Handle Bearings Carefully, do not use bare hands while handling (do not apply heavy shocks)
  • Use Proper Tools (do not use general-purpose tools)
  • Prevent Corrosion (prevent rusting of bearing caused by moisture and corrosive gasses)
  • Open the bearings from packing at the time of mounting.
  • To reduce friction & wear
  • To extend fatigue life of the bearing
  • To prevents corrosion and extends shelf life.
  • To provide protection from foreign material entering the rolling elements.
  • To reduce noise level of the bearing, lowers torque, and assists the bearing in reaching maximum operating speed.
  • To dissipate frictional heat
As a rule of thumb, never more than 30%. If however your application is very high load and very low RPM then a greater grease fill may be beneficial. You should NEVER fill a bearing totally or excess with grease as it will almost certainly hydraulically lock, even leads to bearing failure, especially if the bearing undergoes a relatively quick start up acceleration. If the grease cannot escape then it stops the rolling elements moving.
Grease consists of a base oil in a thickening agent. The thickening agent extends operational and shelf life by slowing the migration and evaporation of the oil. Grease is recommended for low speeds and less torque sensitive applications. Oil is recommended where low torque or high rotational speeds are a consideration. Many popular oils are generally the same as those used as base oils in greases.

Most standard Lithium-based solutions are not designed for high temperatures. Most standard greases will operate consistently at a maximum temperature of 80°C and can withstand brief periods at 110°C.

If your application goes higher than this then you need a more specialised lubricant. If your application goes beyond 350°C then you may need to consider solid lubricants or ceramic bearing materials (or a combination) or consult with manufacturer.

No, unless you use a prescribed flushing agent in a properly environmentally controlled area and the bearing is thoroughly dried post flush and lubricated with the correct amount and type of grease.
NO, Ceramic Hybrid Ball Bearings have demonstrated the capacity to operate under reduced lubrication conditions.
Silicon Nitride is the typical ball material in a Ceramic Bearing. The primary use for ceramic bearings is to extend bearing life by reducing wear. Ceramic balls in a bearing with stainless steel races have been proven to reduce lubricant breakdown and bearing wear.
Advantages of a ceramic bearing include :
  • Smoother running bearing
  • Less vibration and noise
  • Reduced centrifugal loads as the balls spin against the outer ring, due to lighter weight ceramic balls.
  • Increased bearing life Lower bearing temperatures at high rotational speeds
  • Reduced lubrication requirements
This is a general doubt among most of the customers that shining band on the Outer Dia circumference appears due to fitment of the bearing in the housing. But this is a totally wrong conception. This shining band on the outer Dia appears while manufacturing of the bearing when the graphite shoes holding the bearing are little worn out and bearing outer is rotating while grinding the raceways.

This process is called "Black Tempering". To check the physical damage or minor cracks, a sample lot of bearings from a particular batch are coated with special chemicals to check any such damages. Such Chemical coating helps in detecting very minor defects and cracks which can not be detected otherwise. Such colour has no influence on the quality or tolerance of the bearings. It is nothing but a standard bearing only.
NO, this is not used bearing. This is special process done on the bearing to get smoother finish than normal which increase the life of the bearing due to minimal friction.
High Precision Bearings have additional process to ensure very smooth surfaces, very low axial/radial run outs as well as close boundary dimensions. To achieve the same, bearing outer races are given super finish some times which in turn makes them look dull and have uneven finish by naked eye look. But the same bearing when checked with necessary instruments, found to be much more smooth and very accurate in size.
Bearings are manufactured in lot quantities with basic part nos. marking. Afterwards in an additional process while checking tolerance and clearance, the bearings are segregated accordingly and marked (on bearing or on packing, depend on manufacturer), therefore it looks different.
Bearing is manufactured in different components like Inner Race, Outer Race, Rolling Element & Cage. During this stage, basic bearing part no. is marked on the Inner Race or Outer Race as per manufacterers standard. Afterwards as per requirement for specific cage from customer these components are assembled together and during packing the complete designation is mentioned on the packing.