miniature bearings | miniature ball bearings UK | micro 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

People sometimes refer to miniature bearings as instrument bearings or micro bearings. Their compact size and exceptional performance characteristics make them essential components in many industries. They are used in applications as varied as gyros, anemometers, flow meters, miniature gearboxes, small motors and radio controlled models.

Ball bearings are usually made of chrome steel, which is a great choice because of its strength, low-noise characteristics, and affordability. Our chrome steel range of mini ball bearings are available with a flange on the outer ring as shown in Products Variants below.

However, manufacturers only make the smallest, most precise bearings out of stainless steel. Therefore, the cost difference is negligible due to the small amount of steel used in manufacturing. You can find our smallest miniature bearings on the stainless steel miniature bearing page (see Products Variants).

Operating condition considerations for miniature chrome steel bearings

Miniature bearing in chrome steel

Chrome steel bearings can handle temperatures up to 120°C when used continuously, with a steel retainer and proper lubrication. They can also be used up to 150°C intermittently. At temperatures above a certain level, the strength of chrome steel bearings decreases and they experience more of a size change compared to stainless steel. Chrome steel is not ideal for use in corrosive environments, as it does not have corrosion resistance.

To protect against moisture, miniature chrome steel bearings are coated with a preventive oil. We do not suggest using chrome steel ball bearings without lubrication (dry) because they are prone to rusting.

This can even happen when they are not in use or while they are in transit due to condensation forming inside the packaging. You cannot apply the protective oil to a dry bearing. The oil would potentially find its way inside the bearing making it no longer “dry”.

Most of our chrome steel miniature ball 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. However, 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.

Miniature sealed ball bearing

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 information and drawings of the bearings with load and speed data. Please note that the maximum loads and speeds are used in theoretical life calculations. To ensure reasonable bearing life, it is recommended to use bearings at significantly less than the maximum load and speed ratings.

At temperatures above a certain threshold, the maximum load-bearing capacity of chrome steel decreases and it experiences more deformation than stainless steel. Moreover, the steel is not rust-resistant and should not be used in corrosive environments.

To prevent moisture from damaging chrome steel miniature bearings, manufacturers typically coat them with a protective oil. Using chrome steel bearings without lubrication is not recommended as they can rust easily. Rusting can happen when they are stored or shipped, due to moisture inside the protective packaging. Additionally, protective oil cannot be applied to a dry bearing.

Ball bearings frequently have chrome steel components due to their ability to withstand high loads and low noise performance. Additionally, chrome steel bearings are more economical compared to other materials. On the other hand, many miniature instrument bearings are typically manufactured with stainless steel.

For further information about our range of miniature bearings in chrome steel, contact a specialist today by emailing sales@smbbearings.com.

 

See miniature bearings metrics below.

 

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

Flanged Miniature Bearings in Chrome Steel

Chrome Flanged

More Information

miniature bearings | Stainless steel bearing uk

Stainless Steel Miniature Bearings for high precision

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

 

 

 

 

 

 

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.