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Bearing Defects & Preventive Measures

 Wed, 2 Mar, 2022   /    jvnbe123

Bearings must be carefully handled, mounted, and maintained in order to operate properly. Care and attention must be used during and after installation to increase the work life of the bearing, prevent bearing defects, and reduce the cost of repair and replacement.

In case of poor performance or breakdown, the cause of failure must be determined to prevent repetition. There are three types of data which should be gathered to enable the correct diagnosis of bearing problems:

• Time of occurrence
• Symptoms during operation
• Condition of Bearings

Time of Occurrence 

Symptoms During Operation

Condition of Bearings & Prevention Methods

(1) Premature Flaking
The repeated heavy stress cycle between the bearing raceway and rolling element surface results in fatigue cracks which become loosened from bearing materials.
Causes	Counter Measures
Abnormal axial load or excessive load caused by expanded shaft.	Clearance fit for the outer ring of one bearing to allow the floating end to move freely axially.
Deflection or misalignment of shaft.	Correct alignment of shaft and bearing housing.
Poor parallelism of inner and outer rings.	Improve mounting and alignment.
Poor lubrication.	Carefully clean and handle shaft and housing.
Rusting, Nicks, Galling from dirt, etc.	Review type and quantity of lubricant.
(2) Seizure
Bearing is seized up by excessive heat. Discoloration, softening and fusion of raceway and rolling element.
Causes	Counter Measures
Loss of clearance.	Review fitting and bearing clearance.
Operating over limiting speed.	Review type of bearing.
Poor or improper lubricant.	Select a proper lubricant, and feed it in proper quantity.
(3) Breakage
Splits and cracks in the inner/outer ring or rolling element.
Causes	Counter Measures
Excessive interference fit.	Check fits. Finish shaft and sleeve to higher accuracy.
Bearing seat has larger corner radius than bearing.	Make shaft corner radius smaller than that of the bearing.
Excess clearance during operation.	Check fits and bearing clearance.
Excess impact load.	Re-check load conditions.
(4) Indentation
Brinelling, indentation and pear skin of bearing raceway and rolling
element.
Causes	Counter Measures
Impact applied during mounting.	Carefully handle the bearing.
Impact from dropped bearing.	Clean shaft and housing.
Contamination	Improve the sealing.
Load applied to bearing at rest in excess of static load rating.	Re-check load conditions.
(5) Fretting
Occurs when a small relative motion is repeatedly caused in non-rotating bearing. Fretting surface wear produces red colored particles at fitting surface.
Causes	Counter Measures
Vibration applied to bearing at rest (e.g. during shipment).	Fit the shaft and housing during shipment.
Swing with smaller amplitude.	Apply a preload. Use oil for lubrication.
Minute clearance on fit surface.	Increase the interference.
Slight sliding during operation as a result reduced interference under a load.	Apply oil.
(6) Scoring
Metal to metal contact of bearing raceway, flange face, rolling element and retainer due to destruction of oil film.
Causes	Counter Measures
Incorrect lubrication.	Review type and quantity of lubricant.
Contamination by foreign matter.	Improve sealing and component cleaning.
Deflection or misalignment of shaft. Excessive axial load.	Correct mounting errors. Review load conditions.
Sharp speed increase at startup.	Change to smooth acceleration.
(7) Smearing
Metal to metal contact due to the destruction of oil film. Sliding motion between outer/inner ring and rolling element.
Causes	Counter Measures
Excess axial load.	Correct mounting errors.
Misalignment of bearing.	Review the load condition.
Poor lubrication.	Select a proper lubricant, and feed it in proper quantity.
Intrusion and galling caused by foreign matter.	Improve the sealing.
High acceleration on start-up.	Clean shaft and housing.
	Avoid sharp acceleration.

Overview of Spherical Roller Bearings

 Wed, 29 Apr, 2020   /    jvnbe123

Spherical roller bearings are rolling-element bearings that permit rotation with low friction and permits angular misalignment. These bearings support a rotating shaft in the bore of the inner ring that may be misaligned in respect to the outer ring. The misalignment is possible due to the spherical internal shape of the outer ring and spherical rollers. Despite their name, spherical roller bearings are not truly spherical in shape. The rolling elements of spherical roller bearings are mainly cylindrical in shape, but have a profile that makes them appear like cylinders that have been slightly over-inflated. The spherical roller bearing was invented by engineer Arvid Palmgren his design is still in use in modern machines.

How do Spherical Roller Bearings Work?

All spherical roller bearings have the same working principal. They all have outer rings that with concave (spherical) inner raceways. The inner rings similarly have convex outer raceways (or rolling elements that create a matching convex sliding surface). What separates the various types of spherical bearings is the design of their sliding surface. Some are ring-to-ring (such as spherical plain bearings and rod ends), others use rolling elements such as balls or rollers between the inner and outer rings.

Applications of Spherical Roller Bearings

• Gearboxes, Drive Shafts
• Wind Turbines,
• Continuous Casting Machines,
• Pumps,
• Mechanical Fans and Air-Blowers,
• Mining and Construction Equipment,
• Textile Manufacturing
• Wood Working Machinery
• Overhead Crane Moving Wheel
• Pulp and Paper Processing Equipment,
• Marine Propulsion
• Offshore Drilling,
• Off-road vehicles.

Types of Spherical Roller Bearings

• Spherical Roller Bearings: They are designed to work in applications where severe misalignment exists. This maybe due to mounting error or shaft deflection. They deal with relatively heavy radial loads and some axial loads in either direction. They are also extremely resistant to shock loads and their self-aligning feature allows full capacity loading despite shaft deflection. They are very similar in purpose to Self-Aligning Double Row Ball Bearings, except the Spherical Roller Bearings are designed to be more robust by carry heavier loads but at lower maximum speeds.
• Spherical Plain Bearings: (also known as “Spherical Plane Bearings“) are spherical bearings that have an inner ring with a sphere convex outside surface and an outer ring with a correspondingly sphere, but concave inside surface. Their design makes them particularly suitable for bearing arrangements where alignment movements between shaft and housing have to accommodate, or where oscillating or recurrent tilting movements must be permitted at relatively slow sliding speeds.
• Spherical Rod End Bearings: A type of spherical bearing that consists of an eye-shaped head with integral shank forming a housing and a standard spherical plain bearing, or a spherical plain bearing inner ring. As the name implies, they are used at the end of rods and have either a male or female thread for mounting.

Nomenclature of Spherical Roller Bearings

Factors Influencing Quality of Deep Groove Ball Bearings

• Steel Grade: The steel grade used during manufacturing plays a crucial role in determining the life and durability of the bearing. Some similar steel compositions steel types would be AISI 52100 (USA), 100CR6 (Germany), SUJ2 (Japan) and GCR15 (China). They are used extensively for manufacturing bearings.
• Bearing Components: The quality of rollers, cages/seals (steel or brass cages), lubricant (grease, even anti-rust oil), oil grooves (they tend to weaken the structure of the bearing) play an important role in the making of a great bearing. Many Chinese factories use EN31 rollers to reduce cost which may reduce the life of the bearings.
• Design Conformity: The closer the bearing is to the dimensional accuracy of the bearing design standards the better and longer it would be able to perform.
• Essential Processes: Forging , Annealing, Stress Relieving, Hardening and Tempering must be followed to ensure quality bearings.
• Grinding: The bearing’s inner and outer ring raceways need to be thoroughly ground over many cycles to ensure a smooth surface for the rolling elements. Many Chinese factories skip or reduce the number of grinding cycles to reduce cost and offer bearings at cheaper prices.
• Cleaning: SAE 52100 has excellent hardness and wear resistance. It also exhibits good fatigue life in rolling element bearings. However, the corrosion resistance of chrome steel is poor because of the low chromium content. The surfaces of the bearings must be thoroughly cleaned and protected with a coating of rust inhibitor or oil to stop oxidation. Even slight humidity or moisture exposure entails rusting of the bearing surface.
• Assembly and Bearing Handling: Bearings must be handled with care and consideration. Few factories have automated all the processes involved to reduce human intervention and ensure cleanliness and hygiene. Majority of the factories in China rely on labor for the assembly, handling and packing of the bearings. The labor are usually unskilled and seasonal workers who are not properly trained. This leads to contamination and improper handling of bearings. Well trained and experienced labor are crucial to the success of the bearing factories.
• Management: The attitude of the top management towards strict conformance and quality control is paramount to the quality of the bearings produced. Simply having an ISO certificate which can be ‘purchased’ is not enough. Rigorous discipline and attention to detail is required of bearing factories.

Overview of Deep Groove Ball Bearings

 Wed, 18 Mar, 2020   /    jvnbe123

Deep Groove Ball Bearings are the most popular of all bearing types due to their incredible versatility. Some characteristics may include:

• They are Low Friction: optimized for minimal noise and vibration which enables high rotational speeds.
• Accommodate radial, axial and composite loads and are easy to mount.
• They have a wide variety of seals, shield and snap-ring arrangements.
• Require less maintenance compared to other bearing types.

Applications of Deep Groove Ball Bearings

Household Items: Bicycles, Skateboards, Sewing Machines, Washing Machines, Tumble Driers, Food Processors, Hair Dryers, DVD Players, Fishing Rods.
Office Equipment: Photocopiers, Fax Machines, Hard-Drives, Fans, Air-Conditioners
Industries: Electric Motors, Pumps / Compressors, Blowers, Elevators, Assembly Lines, Escalators, Medical and Dental Equipment, High-speed Machine Tooling Equipment, Paper Making Machinery, Chain Saws, Power Tools, Toy Manufacturing, Trains, Wind Turbines.
Automotive: Engines, Steering, Driveshaft and Driveline, Alternators, Gear Boxes, Transmissions, Automotive Starters and many many more.

Types of Deep Groove Ball Bearings

Factors such as speed, load conditions, space availability, and accessibility requirements influence bearing selection. We at JVN Bearings provide a range of ball bearings to our customers which may include:

Miniature Ball Bearings

Miniature Ball Bearings are small bearings with balls as their rolling elements.  These small bearings have an outside diameter of less than 9.525 mm. They typically have 3 digits Ex: 625 2RS These bearings are offered in various ABEC classes, in either chrome or stainless steel. Both metric and inch styles are available.

Deep Groove Radial Ball Bearings

Deep Groove Radial Ball Bearings are the most popular and widely used type of bearing. They are used for heavy radial loads and lower bidirectional thrust loads. Typically employed in high-speed precision applications such as fans or motorbikes. Ex: 6301 ZZ. They can be designed with enhanced metal shields (ZZ) or rubber seals (2RS) . Multiple internal clearances, tolerance grades, and cage designs are offered to suit specific applications’ running precision and speed.

Double Row Deep Groove Ball Bearings

Double Row Deep Groove Ball Bearings are very suitable for bearing arrangements where the load carrying capacity of a single row bearing is inadequate. For the same bore and outside diameter, double row bearings are slightly wider than single row bearings, but have a considerably higher load carrying capacity. Ex: 4210.

Nomenclature of Deep Groove Ball Bearings

Example: What does 6301ZZ C3 Z1V1 mean?
It is a Metric Medium Sized Bearing with a bore diameter of 12mm, which has a loose internal clearance and noise / vibration grade of Z1V1. The above chart gives a brief description about the nomenclature of Deep Groove Ball Bearings. For further details about how to understand bearing nomenclature please read this article.

Factors Influencing Quality of Deep Groove Ball Bearings

• Steel Grade: The steel used during manufacturing plays a crucial role in determining the life and durability of the bearing. A simple “GCR15” or “SAE52100” only describes a range of the composition of steel utilized. The quality varies from factory to factory.
• Bearing Components: The quality of balls, cages/seals, lubricant (grease, even anti-rust oil) play an important role in the making of a great bearing.
• Design Conformity: The closer the bearing is to the dimensional accuracy of the bearing design standards the better and longer it would be able to perform.
• Heat Treatment: Bearings steels are generally purchased in their soft (unhardened / pear-lite) state. Many Chinese factories claim their bearings to be “SAE52100” and ABEC ‘7’ or ‘9’ which may be true, but what they don’t tell you is that they skip essential heat treatment processes which are required to harden bearings and ensure their durability. They simply grind bearings within the ABEC tolerances to save cost.
• Grinding: The bearing’s inner and outer ring raceways need to be thoroughly ground over many cycles to ensure a smooth surface for the rolling elements. Many Chinese factories skip or reduce the number of grinding cycles to reduce cost and offer bearings at cheaper prices.
• Cleaning: SAE 52100 has excellent hardness and wear resistance. It also exhibits good fatigue life in rolling element bearings. However, the corrosion resistance of chrome steel is poor because of the low chromium content. The surfaces of the bearings must be thoroughly cleaned and protected with a coating of rust inhibitor or oil to stop oxidation. Even slight humidity or moisture exposure entails rusting of the bearing surface.
• Assembly and Bearing Handling: Bearings must be handled with care and consideration. Few factories have automated all the processes involved to reduce human intervention and ensure cleanliness and hygiene. Majority of the factories in China rely on labor for the assembly, handling and packing of the bearings. The labor are usually unskilled and seasonal workers who are not properly trained. This leads to contamination and improper handling of bearings. Well trained and experienced labor are crucial to the success of the bearing factories.
• Management: The attitude of the top management towards strict conformance and quality control is paramount to the quality of the bearings produced. Simply having an ISO certificate which can be ‘purchased’ is not enough. Rigorous discipline and attention to detail is required of bearing factories.

Bearing Nomenclature and Numbering Systems

 Thu, 5 Mar, 2020   /    jvnbe123

Bearing numbers can seem very confusing and random to the average person. But there is a system to all the madness!
There are several numbering systems used in the bearing industry today. The boundary dimensions for certain series of bearings are defined in various standards, such as ABMA, JIS and ISO. (Learn more about them here.) In addition, many manufacturers have created their own numbering systems that are a combination of the bearing numbers and a series of codes that define additional specifications.

How to Identify Bearings by their Numbers?

Number Breakdown:

• Types of Bearings
• Series Description
• Bore Size of Bearings
• Shield / Seal Configuration
• Internal Clearance
• Noise and Vibration

Types of Bearings

The first digit of a bearing signifies the type of bearing. For Ex: In a 6208 bearing the first digit being ‘6′ is a Single Row Deep Groove Ball Bearing.
In case of Inch bearings, the bearing’s first digit will be ‘R’. After ‘R’, the size of the bearing will be given in 1/16^th of an inch. For Ex: R6-2RS bearing. Here, R6 signifies, it is an inch bearing whose bore size is 6/16^th of an inch or 0.375 inches.

Series Description

The second digit of a bearing number indicates the Bearing Series which denotes the toughness / strength of the bearing. Bearing strength is the maximum stress load that the unit can “bear” or hold before the structure fails. It can be measured by Tensile Strength, Tensile Elongation, Compressive Strength, Flexural Strength, Modulus and Hardness.

Bore Size of Bearings

The third and fourth digit of a bearing number as indicated above refers to the bore size of the bearing. It is the inner diameter of the bearing and is measured in millimeters. From ’00’ to ’03’ the measurements are noted above. From ’04’ onward the bore size is equal to five times the third and forth digit of bearing’s last two numbers.

In case there is no fourth digit, then the 3rd digit indicates the bore size in mm. For Ex: In case of bearing 625 2RS, the bore size of the bearing will be 5mm.

Thus, we can identify now that in case of bearing 6207ZZ, the third and fourth digit ‘07’ means the bearing’s bore size is 35 mm.

Shield / Seal Configuration

The letters after the bearing number indicates the presence / absence / type of shielding or sealing and any other specialties in the bearing. We can identify now that in case of bearing 6208RS, the last letters ‘RS’ means the bearing is shielded on a single side.

Internal Clearance

Bearing internal clearance means the total distance through which one bearing ring can be moved in relation to the other in the radial direction (radial internal clearance) or in the axial direction (axial internal clearance).

In almost all applications, the initial clearance in a bearing is greater than its running clearance. The difference is mainly caused by:

• The expansion of the inner ring or the compression of the outer ring reduces the internal clearance.
• Bearings generate heat in operation. Differential thermal expansion of the bearing and mating components influences the internal clearance.

Noise and Vibration

Bearing acoustical noise is a function of both (Internal Factors) the bearing itself and (External factors) the way in which it is used. Bearing noise is not generally influenced by ABEC precision, they are independent of precision grades. For Ex. A P6 / ABEC 3 bearing can have a rating of Z2V2 or above. Bearing Noise is affected by the manufacturers’ Internal quality standards with regard to the

• surface finish of the raceways and balls, (through proper grinding, cleaning and dirt free storage)
• roundness of the rings and balls and
• correct cage design.

External factors affecting bearing noise include:

• Lubricant Type,
• Excessive Load,
• Improper Fitting,
• Preload Method,
• Dust Particles and other factors.

The vibration and noise of bearings are classified as four classed as Z1,Z2,Z3 and Z4.It is measured by the instrument of S0910-1.For special requirement, it is measured by BVT-1 and classified as V1, V2, V3 and V4. The classes help consumers select bearings. For Ex: A Z3V3 bearing has an average range of 25-35 dB which is suitable for applications such as in ceiling fans. dB is a measure of volume (loudness of a sound).

Bearing Standards – Precision Levels and Tolerances

 Sun, 14 Jul, 2019   /    jvnbe123

What is a standard?
A standard is a document that specifies requirements for products, services and/or processes, laying down their required characteristics. This helps ensure the free movement of goods and encourages exports. It serves to safeguard people and goods and to improve quality in all areas of life.

How is it developed?
Standards are developed by those who have a need and an interest in using them. The broad participation of all stakeholders, a transparent development process and the consensus principle ensure the wide acceptance of a standard.

Who develops standards for bearings?
There are several bodies that are recognized throughout the world in terms of bearing standards and nomenclature. They are:

• ABMA/ANSI (American Bearing Manufacturers Association / American National Standards Institute): In the US, ABMA maintains the standards deemed necessary by its bearing industry member companies. This includes revising existing or proposing and preparing new standards. These standards are then recommended to the ANSI for approval as US national standards. ANSI has a committee consisting of representatives from user organizations, manufacturers, and the US government that are devoted to rolling bearing standards activities.
• DIN (Deutsches Institut fur Normung): DIN, the German Institute for Standardization, is the independent platform for standardization in Germany and world over. As a partner for industry, research, and society as a whole, DIN plays a major role to support the marketability of innovative solutions through standardization. Their market-oriented standards and specifications promote global trade, encouraging rationalization, quality assurance and environmental protection as well as improving security and communication.
• JIS (Japanese Industrial Standard): The Japanese Industrial Standards Committee (JISC), Japan’s national standardization body, plays a central role in developing standards in Japan covering a wide range of products and technologies from robots to pictograms.
• ISO (International Organization for Standardization): Through its members, it brings together experts to share knowledge and develop voluntary, consensus-based, market-relevant International Standards that support innovation and provide solutions to global challenges.

Tolerance classes for ball bearings were defined by a committee within the ABMA known as the “Annular Bearings Engineers Committee” (ABEC). These tolerances are commonly referred to as ABEC rating or grade. Tolerance classes for roller bearings are covered by the RBEC classifications contained within the same standard.

The ABEC (and RBEC) tolerance classifications specify both tolerances of size and form for the individual inner and outer rings. The critical features of the rings include the bore (or inner diameter of the inner ring), the outer diameter of the outer ring, the ring widths, and the raceways of each ring. Tolerances of the form include roundness, taper, runout, and parallelism.

There are five classes from largest to smallest tolerances: ABEC 1, ABEC 3, ABEC 5, ABEC 7, and ABEC 9. The higher ABEC classes provide better precision, efficiency, and the possibility of greater speed capabilities, but do not necessarily allow the components to spin faster. The ABEC rating does not specify many critical factors, such as load handling capabilities, ball precision, materials, material Rockwell hardness, degree of ball and raceway polishing, noise, vibration, and lubricant. Due to these factors, an ABEC 3 classified bearing could perform better than an ABEC 7 bearing. Bearings not conforming to at least ABEC 1 cannot be classified as precision bearings as their tolerances are too loose.

The scale also works as a guide for consumers to make informed decisions about the type of bearing they desire, despite not knowing factors related to materials, manufacturing, and performance.

High rated bearings are intended for precision applications like aircraft instruments or surgical equipment. Lower graded bearings are intended for the vast majority of applications such as vehicles, mechanical hobbies, skates, skateboards, fishing reels, and industrial machinery. High ABEC rated bearings allow optimal performance of critical applications requiring very high RPM and smooth operation.

Comparison of Tolerance Classifications of National Standards

Table Terminology:
Bearing Tolerances: It refers to three aspects of accuracy:

• Dimensional Accuracy: Dimensional accuracy is a measure of the bearing’s external dimensions, For example, bore diameter (d), outer diameter (D), inner ring width (B), and outer ring width (C). The difference between an actual bearing dimension and the nominal or target value is called the dimensional deviation. The most commonly used measures are the single plane mean bore and outer diameter deviations (Admp and ADmp), and the inner and outer ring width deviations (ABs and ACs). These values are governed by industry standard tolerances. Dimensional accuracy is important for determining shaft and housing fits.
• Machining Accuracy: Machining (or form) accuracy measures the variation in the above example dimensions when a series of measurements is taken on a single bearing and compared to one other. The most common measures are single radial plane bore and outside diameter variation (Vdp and VDp), mean single plane bore and outside diameter variation (Vdmp and VDmp), and inner and outer ring width variation (VBs and VCs). Variation refers to the difference between the largest and smallest measurements in a series, while mean variation refers to the average difference between consecutive measurements.
• Running accuracy: Running accuracy (or runout) is a measure of the degree of eccentricity (for radial runout) and squareness (for bore and O.D. with side face) of the bearing. Inner and outer ring radial runout (Kia and Kea) are the measures most often used. Running accuracy is important to keep excess vibration and misalignment of the assembly at a minimum.

Allowable error limitations for the three areas of bearing accuracy have been internationally standardized for many years as tolerance classes. Each tolerance class specifies a group of limits for all the measures of accuracy (varying in proportion to the bearing size). The most recognized standards are compared in the table above (note that each column represents a set of equivalent classes). For the ISO, JIS, and DiN standards, bearings with standard accuracy are classified as class 0. This is then followed by class 6. From there on, decreasing class numbers denote progressively improving accuracy.

Radial Runout: Radial run-out is the variation of wall thickness in a bearing race. In technical terms, run-out is the measurement of the raceway in which the rolling element rides and how it relates to the outer ring’s outer diameter and the inner ring’s inner diameter as you rotate the bearing 360 degrees. Incorrect run-out can cause a wide variety of issues, depending on the application. For example, if you have a machine designed to create specially aligned holes in a part, incorrect run-out could affect the proper placement of the holes, meaning those holes might not match up with the mating part. In a motor application, you could face issues with vibration or noise.

Table IA

Tolerance Class ABEC-1, RBEC-1
(ISO Class Normal)
Inner Ring

Table IB

Tolerance Class ABEC-1, RBEC-1
(ISO Class Normal)
Outer Ring

Table II A

Tolerance Class ABEC-3, RBEC-3
(ISO Class 6)
Inner Ring

Table II B

Tolerance Class ABEC-3, RBEC-3
(ISO Class 6)
Outer Ring

Table III A

Tolerance Class ABEC-5, RBEC-5
(ISO Class 5)
Inner Ring

Table III B

Tolerance Class ABEC-5, RBEC-5
(ISO Class 5)
Outer Ring

Table IV A

Tolerance Class ABEC-7, RBEC-7
(ISO Class 4)
Inner Ring

Table IV B

Tolerance Class ABEC-7, RBEC-7
(ISO Class 4)
Outer Ring

Table V A

Tolerance Class ABEC-9, RBEC-9
(ISO Class 2)
Inner Ring

Table V B

Tolerance Class ABEC-9, RBEC-9
(ISO Class 2)
Outer Ring

Types of Bearings and Thier Applications

 Sat, 25 May, 2019   /    jvnbe123

There are various types of bearings, each used for specific purposes and designed to carry specific types of loads, i.e., radial loads, thrust loads, or some combination of the two.

1) Ball Bearings

Ball bearings are extremely common because they can handle both radial and thrust loads, but can only handle a small amount of weight. They are further classified into:

• Deep-Groove Ball Bearings: The most widely used roller bearing type in the world due to their versatility and overall performance. They are characterized by having deep raceway grooves in which the inner and outer rings have circular arcs of slightly larger radius than that of the balls. They also have non-separable rings.
• Angular Contact Ball Bearings: Angular contact ball bearings can withstand high radial-axial loads and reach high speeds. They are asymmetrical for manufacturing reasons and can withstand unidirectional axial loads only. Angular bearings are usually mounted in a group of two or more opposed preloaded units with rigid or elastic spacers.

• Self-Aligning Ball Bearings:In a self-aligning bearing, the inner ring has two raceways and the outer ring has a single spherical raceway with its centre of curvature coincident with the bearing axis. This allows the axis of the inner ring, balls and cage to deflect around the bearing centre to automatically correct misalignment caused by housing and shaft machining or installation error.

Application of Ball Bearings:
Household Items: Bicycles, Skateboards, Sewing Machines, Washing Machines, Tumble Driers, Food Processors, Hair Dryers, DVD Players, Fishing Rods.
Office Equipment: Photocopiers, Fax Machines, Hard-Drives, Fans, Air-Conditioners
Industries: Elevators, Assembly Lines, Escalators, Medical and Dental Equipment, High-speed Machine Tooling Equipment, Paper Making Machinery, Chain Saws, Power Tools, Pumps / Compressors. Toy Manufacturing, Trains, Wind Turbines.
Automotive: Engines, Steering, Driveshaft and Driveline, Electric Motors, Gear Boxes, Transmissions

2. Tapered Roller Bearings
Tapered angles allow the bearings to efficiently control a combination of radial and thrust loads. The steeper the outer ring angle, the greater ability the bearing has to handle thrust loads. To provide a true rolling motion of the rollers on the raceways, the extensions of the raceways and the tapered surfaces of the rollers come together at a common point, the apex, on the axis of rotation.
Applications: Agriculture, construction and mining equipment, sports robot combat, axle systems, gearbox, engine motors and reducers, propeller shaft, railroad axle-box, differential, wind turbines, etc.

3. Spherical Roller Bearings
A spherical roller bearing is a rolling-element bearing that permits rotation with low friction and permits angular misalignment. Typically, these bearings support a rotating shaft in the bore of the inner ring that may be misaligned with respect to the outer ring. The misalignment is possible due to the spherical internal shape of the outer ring and spherical rollers. Despite what their name may imply, spherical roller bearings are not truly spherical in shape. The rolling elements of spherical roller bearings are mainly cylindrical in shape but have a profile that makes them appear like cylinders that have been slightly over-inflated.
Applications: Gearboxes, wind turbines, continuous casting machines, material handling, pumps, mechanical fans and blowers, mining and construction equipment, pulp and paper processing equipment, marine propulsion and offshore drilling, off-road vehicles.

4. Cylindrical Roller Bearings

Cylindrical Roller Bearings are designed to carry heavy loads—the primary rolling element is a cylinder, which means the load is distributed over a larger area, enabling the bearing to handle larger amounts of weight. This structure, however, means the bearing can handle primarily radial loads, but is not suited to thrust loads. For applications where space is an issue, a needle bearing can be used. Needle bearings work with small diameter cylinders, so they are easier to fit in smaller applications.
Applications: Mining, petroleum production, power generation, power transmission, cement processing, aggregate crushing, and metal recycling, Briquetting machines, rubber mixing equipment, rolling mills, rotary dryers, or pulp and paper machinery, construction equipment, crushers, electric motors, blowers and fans, gears and drives, plastics machinery, machine tools and traction motors and pumps.

5. Needle Roller Bearings
A needle roller bearing is a special type of roller bearing which uses long, thin cylindrical rollers resembling needles. Ordinary roller bearings rollers are only slightly longer than their diameter, but needle bearings typically have rollers that are at least four times longer than their diameter.
Applications: Needle bearings are heavily used in automobile components such as rocker arm pivots, pumps, gearboxes, automotive power transmission systems, two and four stroke engines, planetary gear sets and air compressors.

6. Slewing Bearings
A slewing bearing or slewing ring is a rotational rolling-element bearing that typically supports a heavy but slow-turning or slow-oscillating load, often a horizontal platform such as a conventional crane, a swing yarder, or the wind-facing platform of a horizontal-axis windmill. (To “slew” means to turn without change of place.) Slewing bearings are often made with gear teeth integral with the inner or outer race, used to drive the platform relative to the base.
Applications: 
Construction: Cranes for Bulk/Scrap handling, shocks vibration ,Handling container Rubber tyre – gantry crane & Reach Stackers, Concrete Pumps and Mixers,
Medical: Radiotherapy applications, pharmaceutical industry for all production steps, mixing, filling, cleaning, etc.
Water Treatment, Offshore Mining, Forest Industries, Radar Military, Manlifts in Fire trucks, etc.

7. Thrust Ball Bearings

A thrust bearing permit rotation between parts, but they are designed to support a high axial load while doing this (parallel to the shaft). Higher speed applications require oil lubrication. Generally, they are composed of two washers (raceways) which may be grooved the rolling balls elements which are typically caged. As opposed to roller thrust bearings, ball thrust bearings can generally operate at higher speeds but at lower loads.

Roller thrust bearings, much like ball thrust bearings, handle thrust loads. The difference, however, lies in the amount of weight the bearing can handle: roller thrust bearings can support significantly larger amounts of thrust load, and are therefore found in car transmissions, where they are used to support helical gears. Gear support, in general, is a common application for roller thrust bearings.
Applications: Thrust bearings are commonly used in automotive, marine, and aerospace applications. They are also used in the main and tail rotor blade grips of RC (radio controlled) helicopters, forward gears in modern car gearboxes, radio antenna masts to reduce the load on an antenna rotator, in an automobile the clutch “throw out” bearing, sometimes called the clutch release bearing.

8. Plain Bearings
Plain bearings are the simplest type of bearing and are composed of just the bearing surface with no rolling elements. They have a high load-carrying capacity, are generally the least expensive and, depending on the materials, have much longer lives than other types.
Applications: Turbomachines, such as power plant steam turbines, compressors operating in critical pipeline applications, ship propeller shafts, etc.

9. Specialized Bearings

There are, of course, several kinds of bearings that are manufactured for specific applications, such as magnetic bearings and giant roller bearings.

• Magnetic Bearings
  A magnetic bearing is a type of bearing that supports a load using magnetic levitation. Magnetic bearings support moving parts without physical contact. For instance, they are able to levitate a rotating shaft and permit relative motion with very low friction and no mechanical wear. Magnetic bearings support the highest speeds of all kinds of bearing and have no maximum relative speed.
  Applications: Magnetic bearings are used in several industrial applications such as electrical power generation, petroleum refinement, machine tool operation and natural gas handling. They are also used in the Zippe-type centrifuge, for uranium enrichment and in turbomolecular pumps, where oil-lubricated bearings would be a source of contamination.
• Jewel Bearings
  Jewel Bearing is a plain bearing in which a metal spindle turns in a jewel-lined pivot hole. The hole is typically shaped like a torus and is slightly larger than the shaft diameter. The jewel material is usually synthetic sapphire or ruby (corundum). Jewel bearings are used in precision instruments where low friction, long life, and dimensional accuracy are important. Application: largest use is in mechanical watches.
• Fluid Bearings
  Fluid Bearings are bearings in which the load is supported by a thin layer of rapidly moving pressurized liquid or gas between the bearing surfaces. Since there is no contact between the moving parts, there is no sliding friction, allowing fluid bearings to have lower friction, wear and vibration than many other types of bearings.
  Applications: Heavy-duty rotating equipment, including in hydroelectric plants to support turbines and generators, heavy machinery such as marine propeller shafts.
• Flexure Bearings
  Flexure Bearings are engineered to be compliant in one or more angular degrees of freedom. Flexure bearings are often part of compliant mechanisms. Flexure bearings serve much of the same function as conventional bearings or hinges in applications which require angular compliance. However, flexures require no lubrication and exhibit very low or no friction.
  Application: Door Hinges, Lids for Pez dispensers, Flip-top covers, etc.

Introduction to Bearings

 Sun, 14 Apr, 2019   /    jvnbe123

What are Bearings?

A bearing is a machine element that constrains relative motion and is used to reduce friction between moving parts of a machine to obtain the desired motion. For example, A load of a rotating fan is supported by a bearing while reducing noise and vibration and restricting the movement to a radial axis.

The main functions of bearings are:

• To reduce friction between moving rotatory parts.
• To support rotating parts of a machine.
• To bear radial and thrust load.

How do Bearings Work?

• Bearings typically have to deal with two kinds of loading, radial, and thrust/axial loads.
• Radial load is the load acting perpendicular to the longitudinal axis. Ex: Fans, Cycles, SkateBoards, Mixers / Food Processors, etc.
• Axial or Thrust load is the load acting parallel to the longitudinal axis. Ex: Bar Stools, Rotating Tables, Screw Jacks, Fluid Control Valves, etc
• The Combined load is the load acting both parallel and perpendicular to the longitudinal axis. Ex: Agriculture Equipment, Gearboxes and axles, engines and reducers, propellers, railroad axles, and mining and construction equipment.
• Depending on where the bearing is being used, it may handle radial loading, thrust loading or a combination of both.

Components / Parts of a Standard Bearing

The standard essential components of a bearing are as follows:

1. Inner Ring:
   The Inner Ring is the smaller of the two bearing rings. It has a groove on its outer diameter to form a raceway for the balls. The surface of outside diameter path is finished to extremely tight tolerances and is honed to be a very smooth surface. The inner ring is mounted on the shaft and it is the rotating element.
2. Outer Ring:
   The Outer Ring is the larger of the two bearing rings. On outer ring, there is a groove on its inside diameter to form a pathway for the balls. It also has the same high precision finish of the inner ring. The outer ring is usually held stationery.
3. Rolling Element: (Balls, Cylindrical Rollers, Spherical Rollers, Tapered Rollers, Needle Rollers):
   The rolling elements separate the inner ring and outer ring and permit the bearing to rotate with minimal friction. The dimension of the rolling elements is made slightly smaller than the track on the inner and outer rings. Rolling element dimensions are controlled to very high accuracy. Surface finish and size variations are important attributes. These attributes are controlled to a micro inch level.
4. Cage (Retainer):
   The purpose of the cage in bearings is to separate the rolling elements, maintaining a constant spacing between the inner and outer rings, to accurately guide the rolling elements in the path during rotation and to prevent the rolling elements from falling out.
5. Lubrication:
   The lubricant is an integral part of a bearing’s standard components. Lubrication is added to reduce friction losses in bearing between inner and outer rings.
6. Other Optional Bearing components:
   The other additional components shields and seals enhance the performance and life of the ball bearing. These optional components are added to the bearing as per the customer requirement to increase the performance of the bearing.
   Shields:
   The shield is a stamped, profiled sheet metal disc. Shield is pressed into a very small groove on the inside edge diameter of the outer ring. A small space or gap remains open between the outside diameter of the inner ring and shield. Because the shield does not contact the inner ring of the bearing, there is no added friction between the shield and bearing. This results in a bearing that has a very low torque. Purpose of shields is to keep larger particles of contamination from entering the bearing.
   Seals:
   The seal is also inserted into the very small groove on the inside, edge diameter of the outer ring. The inner edge of the seal is moulded into a specifically designed lip configuration.

History of Bearings

 Mon, 8 Apr, 2019   /    jvnbe123

The word “bearing” incorporates the meaning of “to bear,” in the sense of “to support,” and “to carry a burden.” This refers to the fact that bearings support and carry the burden of different types of moving elements. Bearings reduce friction and allow a controlled and efficient transmission of power.

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 Fri, 4 Nov, 2016   /    jvnbe123

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 Fri, 4 Nov, 2016   /    jvnbe123