SKF 6308-2Z/C3 40x90x23 Deep Groove Ball Bearing

SKF 6308-2Z/C3 40x90x23 Deep Groove Ball Bearing

SKF 6308-2Z/C3 is a single-row deep groove ball bearing with dimensions of 40x90x23 mm, manufactured by SKF. It has a 40 mm cylindrical bore, 90 mm outside diameter and 23 mm width. The exact 2Z/C3 configuration combines non-contact metal shields on both sides with C3 radial internal clearance greater than Normal.

Complete identification:

SKF -> 6308 -> 2Z -> C3 -> 40x90x23 mm

SKF 6308-2Z/C3 - Characteristics

The SKF 6308-2Z/C3 belongs to the single-row deep groove ball bearing family.

Its deep raceway geometry enables the bearing to carry primarily radial loads while also accommodating axial loads in both directions.

The exact product differs from an open 6308 bearing through its two metal shields, and from a standard-clearance shielded version through its C3 radial internal clearance.

For correct technical identification, the complete SKF designation should therefore be retained:

6308-2Z/C3

rather than reducing the product reference to 6308 alone.

SKF 6308-2Z/C3 - Dimensions

d - Bore diameter: 40 mm
D - Outside diameter: 90 mm
B - Width: 23 mm
Dimensions: 40x90x23 mm
Bore type: Cylindrical
Measurement system: Metric
Number of rows: 1

For this deep groove ball bearing, the third principal dimension is correctly designated B - bearing width.

The three principal mounting dimensions are therefore:

d 40 mm x D 90 mm x B 23 mm

Deep Groove Ball Bearing Construction

SKF 6308-2Z/C3 is a single-row deep groove ball bearing.

The rolling elements operate between deep raceway grooves in the inner and outer rings. This geometry allows radial loading and also provides axial load-carrying capability in both directions.

SKF specifies bearing steel for the bearing and a sheet-metal cage for this exact reference.

The cage separates and guides the rolling elements around the bearing circumference.

The bearing is supplied with grease lubricant and protected on both sides by non-contact shields.

2Z - Non-Contact Metal Shields on Both Sides

The suffix 2Z is an important part of the SKF designation.

For SKF 6308-2Z/C3, 2Z means that the bearing has a shield on both sides. SKF identifies the sealing arrangement as non-contact.

The metal shields help retain lubricant within the bearing and limit the entry of contaminants while avoiding the continuous rubbing contact associated with contacting elastomer seals.

The 2Z configuration should therefore not be treated as identical to a contacting sealed configuration solely because both versions are closed on two sides.

C3 Radial Internal Clearance

The suffix C3 specifies:

Radial internal clearance greater than Normal

Radial internal clearance is the internal freedom of movement between the bearing rings and rolling elements before mounting.

This parameter can be important where the effective operating clearance changes as a result of shaft and housing fits or temperature differences between bearing components.

A SKF 6308-2Z with Normal clearance and SKF 6308-2Z/C3 have the same principal dimensions, but they are not the same complete bearing specification.

If the machine manufacturer specifies C3, this suffix should be retained when selecting the replacement.

Load Ratings

For the SKF 6308-2Z/C3, published technical data specify:

C - Basic dynamic load rating: 42.3 kN

C0 - Basic static load rating: 24 kN

These are standardized bearing load ratings used in engineering calculations.

The basic dynamic load rating is used when evaluating bearing life under rotating load conditions, while the basic static load rating is relevant to static or very slowly moving load conditions and permanent deformation criteria.

Neither value should be interpreted simply as the maximum permissible machine load.

Actual bearing selection requires consideration of the load direction, equivalent bearing load, required life, speed, fits, lubrication, temperature and operating conditions.

Radial and Axial Loads

The deep groove raceway geometry of the SKF 6308-2Z/C3 is primarily suited to radial loads.

This bearing type can also accommodate axial loads in both directions.

Where radial and axial loads occur simultaneously, bearing selection should be based on the resulting equivalent bearing load and required service life rather than dimensions alone.

The amount of permissible axial load cannot be determined solely from the 6308 designation and should be evaluated for the actual operating conditions.

Speed Ratings

Published data for SKF 6308-2Z/C3 specify:

Reference speed: 17,000 rpm

Limiting speed: 8,500 rpm

These values have different technical meanings and should not be treated as interchangeable.

The actual permissible operating speed of a bearing installation depends on factors including load, lubrication, temperature, fits, heat dissipation and operating environment.

The limiting speed should therefore not be interpreted as an unconditional permissible operating speed for every machine.

Bearing Steel and Sheet-Metal Cage

SKF identifies the bearing material for this reference as bearing steel.

The cage design is specified as:

Sheet metal

The cage maintains separation between the balls and guides their movement around the bearing.

Because cage construction can differ between bearing variants and manufacturers, it should not be assumed from the basic 6308 designation alone. For this exact SKF 6308-2Z/C3 reference, a sheet-metal cage is confirmed.

Grease Lubrication

SKF specifies grease as the lubricant for this exact 6308-2Z/C3 configuration.

The two non-contact metal shields help retain the lubricant within the bearing while providing a barrier against contamination.

The shields are not intended to be interpreted as fully contacting seals.

For replacement selection, a 2Z shielded bearing should therefore be distinguished from open and contacting-sealed 6308 variants.

What Does SKF 6308-2Z/C3 Mean?

The complete designation identifies the bearing configuration.

6308 - single-row deep groove ball bearing of the 63 dimension series with a nominal 40 mm bore

2Z - non-contact metal shields on both sides

C3 - radial internal clearance greater than Normal

The complete technical reference is:

SKF 6308-2Z/C3

The designation should be preserved when ordering or cross-referencing the bearing.

SKF 6308-2Z/C3 vs 6308-2Z

Both bearings have the same principal dimensions:

40x90x23 mm

Both also use metal shields on both sides.

The important difference is the radial internal clearance.

6308-2Z/C3: C3 clearance greater than Normal

6308-2Z: does not carry the C3 suffix

Consequently, the two references should not automatically be treated as identical for replacement purposes.

SKF 6308-2Z/C3 vs 6308/C3

The SKF 6308/C3 also has dimensions of 40x90x23 mm and C3 internal clearance, but it does not have the 2Z shielding configuration.

The difference is therefore significant:

6308-2Z/C3: two non-contact metal shields + C3

6308/C3: open bearing + C3

When replacing a bearing, the closure configuration should be retained where required by the application.

Selection and Interchangeability

A bearing from another manufacturer should not be considered a complete equivalent solely because it carries the number 6308 or measures 40x90x23 mm.

For technical interchangeability, compare at least:

Bearing type: single-row deep groove ball bearing
d: 40 mm
D: 90 mm
B: 23 mm
Closure: non-contact metal shields on both sides
Internal clearance: C3
Load ratings: appropriate for the application
Speed capability: appropriate for the application
Cage: compatible with application requirements
Lubrication: appropriate for the operating conditions

Additional requirements such as tolerance class, noise specification, grease specification or special execution should also be retained if specified by the machine manufacturer.

Technical Specification

Manufacturer: SKF
Manufacturer designation: 6308-2Z/C3
Bearing type: Single-row deep groove ball bearing
Dimensions: 40x90x23 mm
d - Bore diameter: 40 mm
D - Outside diameter: 90 mm
B - Width: 23 mm
Bore: Cylindrical
Number of rows: 1
Closure: Shield on both sides
Shield type: Non-contact metal shields
Radial internal clearance: C3 - greater than Normal
Bearing material: Bearing steel
Cage design: Sheet metal
Lubricant: Grease
Basic dynamic load rating C: 42.3 kN
Basic static load rating C0: 24 kN
Reference speed: 17,000 rpm
Limiting speed: 8,500 rpm
Net/catalog mass: approximately 0.65 kg

FAQ

What are the dimensions of SKF 6308-2Z/C3?

SKF 6308-2Z/C3 measures 40x90x23 mm: 40 mm bore diameter, 90 mm outside diameter and 23 mm width.

What does 2Z mean in SKF 6308-2Z/C3?

2Z specifies non-contact metal shields on both sides of the bearing.

What does C3 mean in SKF 6308-2Z/C3?

C3 means that the radial internal clearance is greater than the Normal clearance class.

Is SKF 6308-2Z/C3 a deep groove ball bearing?

Yes. It is a single-row deep groove ball bearing.

What loads can SKF 6308-2Z/C3 carry?

Its construction is primarily intended for radial loads and can also accommodate axial loads in both directions. SKF catalog ratings for this reference are 42.3 kN dynamic and 24 kN static.

Is SKF 6308-2Z the same as 6308-2Z/C3?

No. Their principal dimensions and shielding are the same, but 6308-2Z/C3 specifically has C3 radial internal clearance greater than Normal.

Can another brand of 6308 ZZ C3 replace SKF 6308-2Z/C3?

Not on designation and dimensions alone. Verify the bearing type, 40x90x23 dimensions, double non-contact shielding, C3 clearance, load ratings, speed capability, cage and any application-specific requirements.

Is 6308 ZZ C3 the official SKF designation?

For this SKF product, the manufacturer designation is 6308-2Z/C3. The expression "6308 ZZ C3" is commonly encountered commercially, but the SKF designation should be retained in the technical product identification.

AI Overview

SKF 6308-2Z/C3 is a single-row deep groove ball bearing measuring 40x90x23 mm, with a 40 mm cylindrical bore, 90 mm outside diameter and 23 mm width. The 2Z suffix identifies non-contact metal shields on both sides, while C3 specifies radial internal clearance greater than Normal. Its basic dynamic load rating is 42.3 kN.