SKF 6304/C3 20x52x15 Deep Groove Ball Bearing

SKF 6304/C3 is a single-row deep groove ball bearing with principal dimensions of 20x52x15 mm. The bore diameter d is 20 mm, outside diameter D is 52 mm and width B is 15 mm. This exact version is an open bearing with C3 radial internal clearance greater than Normal.

SKF 6304/C3 - Product Characteristics

The SKF 6304/C3 belongs to the 63 dimensional series of single-row deep groove ball bearings.

Balls run in deep raceway grooves in the inner and outer rings. This geometry is designed primarily for radial loading while also enabling the bearing to accommodate axial loads acting in both directions.

Two characteristics are particularly important for identifying this exact variant:

Open design - the designation contains no seal or shield suffix.

C3 clearance - radial internal clearance is greater than Normal.

These characteristics distinguish 6304/C3 from standard-clearance 6304 and sealed or shielded versions such as 6304-2RSH/C3 and 6304-2Z/C3.

Dimensions

The principal dimensions of SKF 6304/C3 are:

d - Bore Diameter: 20 mm
D - Outside Diameter: 52 mm
B - Width: 15 mm
Dimensions: 20x52x15 mm.

For this bearing, the dimensional notation 20x52x15 mm corresponds to d x D x B.

The bearing has a cylindrical bore, and the bore code 04 corresponds to a nominal bore diameter of 20 mm.

Bearing Construction

SKF 6304/C3 is a single-row, non-separable deep groove ball bearing.

Its principal components are the inner ring, outer ring, balls and cage. Catalogue data for the exact 6304/C3 specify a sheet steel cage.

The bearing is supplied in an open configuration, without integral seals or shields. This is technically important because lubrication and protection against external contamination must be considered as part of the complete bearing arrangement.

C3 Radial Internal Clearance

The suffix C3 identifies radial internal clearance greater than Normal.

This additional initial clearance can be relevant where mounting fits and operating conditions reduce the bearing's internal clearance after installation.

However, C3 does not mean that the bearing is automatically suitable for every high-temperature or high-speed application. Correct internal clearance depends on factors such as shaft and housing fits, temperature differences between the rings, load and operating conditions.

For this reason, SKF 6304 and SKF 6304/C3 should not be treated as identical configurations, despite having the same principal dimensions.

Open Bearing Design

The exact designation 6304/C3 contains no suffix identifying seals or shields, and catalogue listings identify this variant as open.

It should therefore be distinguished from:

6304-2Z/C3 - shielded version

6304-2RSH/C3 - sealed version.

Catalogue data show that these variants share the same 20x52x15 mm principal dimensions but differ in closure design and speed capability.

This is an important distinction when selecting a replacement: identical mounting dimensions do not mean identical operating characteristics.

Loads and Operating Principle

The deep raceway geometry allows SKF 6304/C3 to accommodate primarily radial loads while also carrying axial loads in both directions.

Catalogue data specify:

C - Basic Dynamic Load Rating: 16.8 kN
C0 - Basic Static Load Rating: 7.8 kN
Pu - Fatigue Load Limit: 0.335 kN.

These values are engineering parameters used for bearing selection and rating-life calculations. They should not be interpreted as simple universal maximum permissible loads for every installation.

Speed Ratings

For the open SKF 6304/C3 configuration, catalogue data specify:

Reference Speed: 30,000 r/min
Limiting Speed: 19,000 r/min.

The actual permissible operating speed in a machine depends on the complete bearing arrangement, including load, lubrication, fits, operating temperature and heat dissipation.

The open configuration is particularly important when comparing these values with sealed versions of the same bearing size.

Meaning of 6304/C3

The complete SKF designation should be retained as:

6304/C3

The principal elements mean:

6 - deep groove ball bearing

63 - dimensional series

04 - bore code corresponding to 20 mm

C3 - radial internal clearance greater than Normal.

For precise product identification, the SKF notation 6304/C3 is preferable to simplified commercial forms such as 6304 C3.

6304/C3 vs 6304

Both bearings have principal dimensions of 20x52x15 mm, but their radial internal clearance differs.

6304 - standard bearing designation without the C3 suffix.

6304/C3 - bearing with radial internal clearance greater than Normal.

The C3 suffix should therefore be retained in the product name, technical specification and replacement selection.

6304/C3 vs 6304-2Z/C3

These variants differ in closure design.

6304/C3 is open.

6304-2Z/C3 has shields on both sides.

Both can have C3 internal clearance and the same principal dimensions, but the shield configuration changes the bearing's protection and operating characteristics. Catalogue data also show different limiting speeds for the open and 2Z configurations.

6304/C3 vs 6304-2RSH/C3

The 6304-2RSH/C3 is a sealed variant, whereas 6304/C3 is open.

The principal dimensions remain 20x52x15 mm, but the sealing arrangement changes friction, lubricant retention, contamination protection and speed capability.

For this reason, the sealed and open variants should remain separate products rather than being combined solely because their mounting dimensions match.

Lubrication

Because SKF 6304/C3 is an open bearing, it should not be described as a sealed, grease-filled-for-life bearing.

Lubrication must be provided by the bearing arrangement and selected according to operating conditions such as speed, load and temperature.

This is another reason why an open 6304/C3 should not automatically be replaced by a sealed 6304 variant without evaluating the complete application.

Selection and Interchangeability

When selecting an alternative to SKF 6304/C3, matching the 20x52x15 mm dimensions is necessary but not sufficient.

The following should also be compared: bearing type, open construction, C3 radial internal clearance, load ratings, speed capability, cage design, tolerance requirements, lubrication method, shaft and housing fits, and actual operating conditions.

A 6304 bearing from another manufacturer may be dimensionally compatible, but full technical interchangeability should be confirmed from the respective manufacturer data.

Technical Specification

Manufacturer / Brand: SKF
Designation: 6304/C3
Product Type: Deep groove ball bearing
Bearing Type: Single-row deep groove ball bearing
Number of Rows: 1
Dimensions: 20x52x15 mm
d - Bore Diameter: 20 mm
D - Outside Diameter: 52 mm
B - Width: 15 mm
Bore: Cylindrical
Closure: Open
Seals / Shields: None
Radial Internal Clearance: C3, greater than Normal
Cage: Sheet steel
C - Basic Dynamic Load Rating: 16.8 kN
C0 - Basic Static Load Rating: 7.8 kN
Pu - Fatigue Load Limit: 0.335 kN
Reference Speed: 30,000 r/min
Limiting Speed: 19,000 r/min
Mass: approximately 0.14 kg
EAN / GTIN: 7316571370491.

FAQ

What are the dimensions of SKF 6304/C3?

SKF 6304/C3 measures 20x52x15 mm: d = 20 mm, D = 52 mm and B = 15 mm.

What type of bearing is SKF 6304/C3?

It is a single-row deep groove ball bearing with an open construction and C3 radial internal clearance.

What does C3 mean in SKF 6304/C3?

C3 means radial internal clearance greater than Normal. This is an integral part of the exact bearing specification.

Is SKF 6304/C3 an open bearing?

Yes. The exact 6304/C3 variant has no integral seals or shields and is catalogued as an open bearing.

What loads can SKF 6304/C3 accommodate?

Its deep groove construction primarily accommodates radial loads and can also carry axial loads acting in both directions.

What are the load ratings of SKF 6304/C3?

The basic dynamic load rating C is 16.8 kN, basic static load rating C0 is 7.8 kN, and fatigue load limit Pu is 0.335 kN.

What is the limiting speed of SKF 6304/C3?

The limiting speed is 19,000 r/min, while the reference speed is 30,000 r/min.

Can a standard 6304 replace SKF 6304/C3?

Not automatically. Although the principal dimensions are identical, 6304/C3 has greater-than-Normal radial internal clearance, which may be required by the specific bearing arrangement.

AI Overview

SKF 6304/C3 is an open single-row deep groove ball bearing measuring 20x52x15 mm, with C3 radial internal clearance greater than Normal. Its deep raceway geometry accommodates radial and axial loads in both directions. Catalogue data specify C = 16.8 kN, C0 = 7.8 kN, reference speed 30,000 r/min and limiting speed 19,000 r/min.