When it comes to rotating equipment reliability, few components are as critical as the bearing. Load capacity, speed capability, lubrication strategy, internal clearance, cage design, and sealing configuration all influence equipment life and performance.
SKF is one of the world’s leading bearing manufacturers, recognized for advanced metallurgy, precision grinding, and application-driven engineering. At Apollo Industries (ApolloUSA.com), we supply and support SKF bearings across automotive, aerospace, HVAC, power transmission, CNC, and heavy industrial markets.
This technical guide will cover:
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Major SKF bearing types
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Engineering principles and load classifications
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Internal clearance and tolerance classes
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Seal and shield configurations
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How to read SKF prefixes and suffixes
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How our upcoming Bearing Code Explorer App simplifies identification
SKF Bearing Types and Engineering Design
SKF manufactures a broad range of rolling element bearings, each optimized for specific load and speed conditions.
1. Deep Groove Ball Bearings
Deep groove bearings are the most common and versatile rolling bearing type.
Engineering Characteristics:
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Designed primarily for radial loads
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Capable of handling moderate axial loads in both directions
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Low friction coefficient
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High-speed capability
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Minimal maintenance in sealed versions
Common series include:
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6000 (light duty)
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6200 (medium duty)
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6300 (heavy duty)
These bearings are widely used in:
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Electric motors
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Pumps
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HVAC blowers
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Gearboxes
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Agricultural equipment
Example:
SKF 6208-2RS1/C3
Breakdown:
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6208 → Medium series, 40 mm bore
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2RS1 → Two contact rubber seals
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C3 → Increased internal radial clearance
2. Angular Contact Ball Bearings
Designed for combined radial and axial loads.
Engineering Characteristics:
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Contact angle (typically 15°, 25°, 40°) determines thrust capacity
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Can be mounted in matched sets (DB, DF, DT)
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High precision grades available (P4, P5)
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High-speed capability
Applications:
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CNC spindles
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Pumps
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Compressors
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Machine tool assemblies
3. Spherical Roller Bearings
Designed to accommodate misalignment and heavy loads.
Engineering Characteristics:
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Self-aligning capability
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Very high radial load capacity
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Moderate axial load capacity
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Robust cage designs
Used in:
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Mining equipment
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Paper mills
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Heavy conveyors
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Industrial gearboxes
4. Tapered Roller Bearings
Optimized for combined radial and axial loads.
Common in:
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Automotive wheel hubs
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Axles
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Gear reducers
SKF tapered bearings are engineered for optimal contact geometry to improve load distribution and extend L10 life.
Internal Clearance and Its Importance
Internal clearance refers to the total distance one ring can move relative to the other.
SKF clearance classes:
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CN (Normal)
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C2 – Less than normal
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C3 – Greater than normal
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C4 – Greater than C3
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C5 – Very high clearance
Why Clearance Matters
When bearings are press-fit into tight housings or onto shafts, internal clearance decreases. If insufficient clearance remains after mounting:
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Bearing preload increases
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Operating temperature rises
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Lubricant breaks down
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Premature failure occurs
In many electric motor applications, C3 clearance is preferred to compensate for interference fits.
Seal and Shield Configurations
SKF uses standardized suffixes to designate sealing and shielding options.
| Suffix | Description | Protection Level | Speed Impact |
|---|---|---|---|
| Z | Single metal shield | Light contamination | Minimal |
| ZZ | Two metal shields | Moderate protection | Minimal |
| RS1 | Single contact seal | High protection | Slight reduction |
| 2RS1 | Two contact seals | Maximum contamination protection | Slight reduction |
| RSH | Improved low-friction seal | High protection | Better high-speed capability |
Example:
SKF 6301-2Z
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Deep groove bearing
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Two metal shields
SKF 6301-2RS1
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Same bearing
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Dual rubber contact seals
Seal choice directly affects:
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Contamination resistance
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Lubricant retention
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Speed rating
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Temperature limits
SKF Precision and Tolerance Classes
SKF bearings conform to ISO standards and may be manufactured in precision classes:
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P0 (Normal)
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P6
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P5
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P4 (High precision)
Higher precision bearings are used in:
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CNC spindles
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Aerospace
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High-speed electric motors
Precision influences:
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Runout
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Noise
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Vibration
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Operating temperature
How to Read SKF Bearing Numbers
SKF part numbers follow a structured format that communicates critical engineering information.
Example:
SKF 6208-2RS1/C3
Step 1: Basic Bearing Designation
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First digit → Bearing type
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Second digit → Width/robustness series
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Last two digits → Bore size
Bore calculation rule:
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For bore codes 04 and above → Multiply by 5
Example:
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08 × 5 = 40 mm bore
Step 2: Suffixes
Common SKF suffixes include:
| Suffix | Meaning |
|---|---|
| 2RS1 | Two rubber seals |
| 2Z | Two metal shields |
| C3 | Increased internal clearance |
| C4 | Extra internal clearance |
| TN9 | Glass fiber reinforced polyamide cage |
| VA201 | High-temperature design |
| NR | Snap ring groove |
Each suffix changes performance characteristics.
Cage Designs and Material Options
Cage material affects:
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Speed capability
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Noise
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Temperature tolerance
Common SKF cage suffixes:
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M – Machined brass cage
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TN9 – Polyamide cage
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J – Pressed steel cage
High-speed applications often benefit from lightweight polyamide cages.
Real-World Application Examples
Electric Motors
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6200 and 6300 series
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Often C3 clearance
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Shielded or sealed
HVAC Equipment
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Sealed deep groove bearings
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Moderate speed
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Contamination protection critical
Heavy Industry
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Spherical roller bearings
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High radial loads
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Misalignment tolerance required
CNC and Precision Machinery
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Angular contact matched sets
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P4 precision
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Controlled preload
Why Suffix Identification Is Critical
Incorrect interpretation of a suffix can result in:
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Wrong clearance selection
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Incompatible lubrication
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Reduced RPM capability
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Seal failure
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Excessive heat
At Apollo Industries, we frequently assist customers in decoding SKF part numbers to prevent ordering errors and downtime.
Introducing the Apollo Bearing Code Explorer App
At the bottom of this blog page, you will find access to our upcoming Apollo Bearing Code Explorer App.
This tool will allow you to:
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Decode SKF prefixes and suffixes instantly
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Compare clearance classes
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Understand seal configurations
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Identify cage types
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Cross-reference alternate part numbers
Designed for engineers, maintenance supervisors, and purchasing professionals, this app removes uncertainty from bearing selection.
Conclusion
SKF bearings represent advanced engineering, global manufacturing expertise, and industry-proven reliability. From deep groove ball bearings to spherical and angular contact designs, every prefix and suffix provides critical technical information.
Understanding how to interpret these designations ensures:
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Correct fit and clearance
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Optimal load capacity
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Improved operating temperature control
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Extended bearing life
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Reduced downtime
At Apollo Industries (ApolloUSA.com), we combine product supply with application expertise to ensure you select the right SKF bearing the first time.
If you need technical support, cross-references, or assistance decoding a complex SKF part number, contact our team today.
Apollo Industries – Precision Components. Engineered Solutions. Reliable Supply.