miniature bearings | miniature bearings UK | miniature ball bearings

Chrome steel miniature bearings for shaft sizes from 1.5mm to 9mm
Dimensions and technical drawings are shown in the product tables below
See Products Variants below for stainless steel and flanged options

Miniature bearings are sometimes referred to as instrument bearings or micro bearings and are used in applications as varied as gyros, anemometers, flow meters, miniature gearboxes, small motors and radio controlled models. Our chrome steel miniature bearings are also available with a flange on the outer ring as shown in Products Variants below.

Chrome steel is the most common material for ball bearings due to its high load capacity and good low noise properties. Chrome steel bearings are also more cost-effective. However, many of the very small, instrument bearings are only made from stainless steel as they are not used in high load applications and the cost difference is negligible due to the small amount of steel used. Our smallest miniature bearings can be found on the stainless steel miniature bearing page (see Products Variants).

Chrome steel bearings, with a steel retainer and a suitable lubricant, can be used at temperatures of 120°C constant or up to 150°C intermittent. Above these temperatures, the load capacity of chrome steel is reduced and the steel undergoes more of a dimensional change than stainless steel.

Chrome steel bearings are not suitable for use in corrosive environments as the steel is not corrosion resistant. Chrome steel miniature bearings are coated with a layer of preservative oil to protect against moisture. We do not recommend using chrome steel bearings without any lubricant (dry) as they are prone to corrosion. This may even occur while in storage or during shipping as a result of condensation forming inside the protective packaging. Protective oil cannot be applied to the outside of a dry bearing as it would find its way inside the bearing making the bearing no longer “dry”.

Most of our chrome steel miniature bearings can be supplied open or with metal shields. The larger sizes may be available with rubber or Teflon contact seals or low friction non-contact rubber seals. Open bearings are supplied with a light oil lubrication. Shielded or sealed bearings are usually supplied with grease lubrication but shielded bearings can be offered with instrument oil for low speed, low friction applications. Thanks to our in-house relubrication facility, these miniature bearings can be offered with customer specified oils, greases or dry lubricants.

The standard cage or retainer for a chrome steel miniature bearing is made from SPCC steel strip. A one-piece crown cage is more common for the smallest and the thinnest bearings due to space constraints. Larger sizes have a two piece ribbon cage. Some sizes are available with a high speed TW nylon crown cage although operating temperatures should be kept under 120°C for this retainer.

Click on INFO in the rows below to display technical drawings of the bearings with load and speed data. Please note that the maximum loads and speeds are used in theoretical life calculations. It is recommended to use bearings at significantly less than the maximum load and speed ratings to ensure reasonable bearing life.

 

Products Variants
miniature bearings | miniature bearing UK | flanged miniature bearings

Flanged Miniature Bearings

Chrome Flanged

More Information

miniature bearings | Stainless steel bearing uk

Stainless Steel Miniature Bearings

Stainless

More Information

Miniature Bearings Metric | Miniature Bearings UK

Stainless Steel Flanged Miniature Bearings

Stainless Flanged

More Information

Product Details Chrome

BORE

(mm)

O.D.

(Mm)

OPEN BEARING

SHIELDED BEARING

SEALED BEARING

WIDTH

(mm)

SMB

REFERENCE

MORE INFO

WIDTH

(mm)

SMB

REFERENCE

MORE INFO

WIDTH

(mm)

SMB

REFERENCE

MORE INFO

1.5

4

1.2

681X

info

2

681XZZ

info

 

 

 

5

2

691X

info

2.6

691XZZ

info

 

 

 

6

2.5

601X

info

3

601XZZ

info

 

 

 

2

5

1.5

682

info

2.3

682ZZ

info

 

 

 

5

2

MR52

info

2.5

MR52ZZ

info

 

 

 

6

2.3

692

info

3

692ZZ

info

 

 

 

6

 

 

 

2.3

692ZZW23

info

 

 

 

6

2.5

MR62

info

2.5

MR62ZZ

info

 

 

 

7

2.5

MR72

info

3

MR72ZZ

info

 

 

 

7

2.8

602

info

3.5

602ZZ

info

 

 

 

2.5

6

1.8

682X

info

2.6

682XZZ

info

 

 

 

7

2.5

692X

info

3.5

692XZZ

info

 

 

 

8

2.8

602X

info

4

602XZZ

info

 

 

 

8

 

 

 

2.8

602XZZW28

info

 

 

 

3

6

2

MR63

info

2.5

MR63ZZ

info

 

 

 

7

2

683

info

3

683ZZ

info

 

 

 

8

2.5

MR83

info

3

MR83ZZ

info

 

 

 

8

3

693

info

4

693ZZ

info

 

 

 

9

2.5

MR93

info

4

MR93ZZ

info

 

 

 

9

3

603

info

5

603ZZ

info

 

 

 

10

4

623

info

4

623ZZ

info

4

623-2RS

info

13

5

633

info

5

633ZZ

info

5

633-2RS

info

3.5

9

 

 

 

4

684ZZB35

info

 

 

 

4

7

2

MR74

info

2.5

MR74ZZ

info

 

 

 

8

2

MR84

info

3

MR84ZZ

info

3

MR84-2RS

info

9

2.5

684

info

4

684ZZ

info

4

684-2RS

info

9

 

 

 

3.5

684ZZW35

info

 

 

 

10

3

MR104

info

4

MR104ZZ

info

 

 

 

11

4

694

info

4

694ZZ

info

4

694-2RS

info

12

4

604

info

4

604ZZ

info

4

604-2RS

info

13

5

624

info

5

624ZZ

info

5

624-2RS

info

16

5

634

info

5

634ZZ

info

5

634-2RS

info

5

8

2

MR85

info

2.5

MR85ZZ

info

2.5

MR85-2RS

info

9

2.5

MR95

info

3

MR95ZZ

info

3

MR95-2RS

info

10

3

MR105

info

4

MR105ZZ

info

4

MR105-2RS

info

11

 

 

 

4

MR115ZZ

info

4

MR115-2RS

info

11

3

685

info

5

685ZZ

info

5

685-2RS

info

13

4

695

info

4

695ZZ

info

4

695-2RS

info

13

 

 

 

5

695ZZW5

info

 

 

 

14

5

605

info

5

605ZZ

info

5

605-2RS

info

16

5

625

info

5

625ZZ

info

5

625-2RS

info

19

6

635

info

6

635ZZ

info

6

635-2RS

info

6

10

2.5

MR106

info

3

MR106ZZ

info

3

MR106-2RS

info

12

3

MR126

info

4

MR126ZZ

info

4

MR126-2RS

info

13

3.5

686

info

5

686ZZ

info

5

686-2RS

info

13

 

 

 

4.5

686ZZW45

info

4.5

686-2RSW45

info

15

5

696

info

5

696ZZ

info

5

696-2RS

info

16

 

 

 

5

696AZZ

info

5

696A-2RS

info

17

6

606

info

6

606ZZ

info

6

606-2RS

info

19

6

626

info

6

626ZZ

info

6

626-2RS

info

19

 

 

 

8

626ZZW8

info

 

 

 

19

 

 

 

 

 

 

5.15

626-2RSW515

info

22

7

636

info

7

636ZZ

info

7

636-2RS

info

7

11

2.5

MR117

info

3

MR117ZZ

info

 

 

 

13

3

MR137

info

4

MR137ZZ

info

 

 

 

14

3.5

687

info

5

687ZZ

info

5

687-2RS

info

14

4

687W4

info

 

 

 

 

 

 

17

5

697

info

5

697ZZ

info

5

697-2RS

info

19

6

607

info

6

607ZZ

info

6

607-2RS

info

22

7

627

info

7

627ZZ

info

7

627-2RS

info

26

9

637

info

9

637ZZ

info

9

637-2RS

info

8

12

2.5

MR128

info

3.5

MR128ZZ

info

3.5

MR128-2RS

info

14

3.5

MR148

info

4

MR148ZZ

info

4

MR148-2RS

info

16

4

688

info

5

688ZZ

info

5

688-2RS

info

16

 

 

 

4

688ZZW4

info

4

688-2RSW4

info

16

 

 

 

6

688ZZW6

info

6

688-2RSW6

info

19

6

698

info

6

698ZZ

info

6

698-2RS

info

22

7

608

info

7

608ZZ

info

7

608-2RS

info

22

6

608W6

info

 

 

 

 

 

 

22

 

 

 

10.3

608ZZW103

info

10.3

608-2RSW103

info

22

 

 

 

 

 

 

11

608-2RSW11

info

24

8

628

info

8

628ZZ

info

8

628-2RS

info

28

9

638

info

9

638ZZ

info

9

638-2RS

info

9

14

3

679

info

4.5

679ZZ

info

 

 

 

17

4

689

info

5

689ZZ

info

5

689-2RS

info

17

 

 

 

6

689ZZW6

info

6

689-2RSW6

info

20

6

699

info

6

699ZZ

info

6

699-2RS

info

24

7

609

info

7

609ZZ

info

7

609-2RS

info

26

8

629

info

8

629ZZ

info

8

629-2RS

info

30

10

639

info

10

639ZZ

info

 

 

 

Our determination to remain specialised gives us a high level of product knowledge, providing bearing and lubrication solutions to existing or potential customers, whether individuals or large corporations. We don’t just sell bearings, we help to solve your problems. - Chris Johnson, managing director of SMB Bearings.