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  • Overview of Deep Groove Ball Bearings

    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

    Deep Groove Ball Bearing Nomenclature
    Deep Groove Ball Bearing Nomenclature

    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.

    Deep Groove Ball Bearings

    Bearing Nomenclature and Numbering Systems

    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?

    Bearing Number Breakdown, Bearing Nomenclature
    Summary of Bearing Number Breakdown

    Number Breakdown:

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

    Types of Bearings

    Type Code Bearing Name
    1 Self Aligning Ball Bearings
    2 Spherical Ball Bearings
    3 Taper Roller Bearings
    4 Double Row Ball Bearings
    5 Thrust Ball Bearings
    6 Single Row Deep Groove Ball Bearings
    7 Single Row Angular Contact Bearings
    N Single Row Cylindrical Roller Bearings
    NA Needle Roller 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 1/16th of an inch. For Ex: R6-2RS bearing. Here, R6 signifies, it is an inch bearing whose bore size is 6/16th of an inch or 0.375 inches.

    Series Description

    Series Code Toughness Description
    0 Extra Light
    1 Extra Light Thrust
    2 Light
    3 Medium
    4 Heavy
    8 Extra Thin Section
    9 Very Thin Section

    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

    Last Digits Bore Size
    (04 and Up: Multiply Last Two Numbers by 5 to get bore in MM)
    00 10
    01 12
    02 15
    03 17
    04 (x5) = 20
    05 (x5) = 25
    06 (x5) = 30 and so on.

    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

    Shield / Seal Code Description
    Z Single Side Metal Shield
    ZZ Both Sides Metal Shield
    RS Single Rubber Seal
    2RS Both Sides Rubber Seal
    V Single Non-Contact Seal
    VV Double Non-Contact Seal
    DDU Double Contact Seal
    NR Snap Ring and Groove
    M Brass Cage

    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

    Example of Internal Clearance
Radial Clearance and Axial Clearance
    Radial Clearance & Axial Clearance
    Internal Clearance
    C2 : Tight
    C0 : Normal
    C3 : Loose
    C4 : Extra Loose

    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

    Noise / Vibration Level
    Z1V1 : Good
    Z2V2 : Better than Z1V1
    Z3V3 : Better than Z2V2
    Z4V4 : Best

    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).

    DecibelsExample Source
    50Relaxed Conversation
    80Food Processor, Lawn Mower
    110Rock Concert, Chainsaw

    Bearing Nomenclature, Numbers and Markings

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