Ball bearings in popular metric sizes for shaft sizes from 10mm to 30mm
Ball bearings are essential components in many mechanical systems, providing smooth motion and reliable support for both radial and axial loads. This guide focuses on popular metric ball bearings designed for shaft sizes ranging from 10mm to 30mm
Different types of ball bearings
While deep groove ball bearings are the most common type, not all ball bearings are deep groove designs. Other types include:
Angular contact ball bearings
Angular contact ball bearings are also designed to support both radial and axial forces simultaneously but can handle much greater axial loads in one direction than deep groove types. The load capacity depends on the contact angle — the greater the angle, the higher the axial load capability. They are commonly used in applications requiring high speed and precision, such as machine tool spindles, pumps and gearboxes. They can be supplied as paired bearings to provide greater rigidity and running accuracy. When mounted together, a preload is introduced and in face-to-face or back-to-back configurations, they can support axial loads in both directions.
Self-aligning ball bearings
Self-aligning ball bearings are engineered to compensate for shaft misalignment and mounting errors. They feature two rows of balls with a common spherical raceway in the outer ring, allowing the bearing to adjust automatically to angular deviations. This design reduces stress and ensures smooth operation, even when the shaft or housing is not perfectly aligned. They are widely used in textile machinery, conveyors, fans and agricultural equipment, where flexibility and reliability are essential.
Miniature ball bearings
Miniature ball bearings are compact, lightweight and precise, making them ideal for applications where space, speed and efficiency are critical. Despite their small size, they offer excellent rotational accuracy and low friction. Common uses include medical instruments, robotics, precision tools and electronic devices. Their small dimensions allow engineers to design high-performance systems with reduced noise and vibration while maintaining smooth, reliable operation.
Thrust ball bearings
Thrust ball bearings are designed specifically to support axial loads while permitting free rotation. They consist of ball assemblies sandwiched between flat or grooved washers. Those with flat washers will support axial loads in both directions while the groove type thrust bearings have a raceway in each washer with allows for greater axial loads in one direction only. These bearings are not intended for radial loads but excel in applications that require smooth axial movement under pressure. Typical uses include industrial fans, aerospace components, automotive systems and mining equipment, where dependable axial support is essential.
Deep groove ball bearings
Deep groove ball bearingsare the most versatile, capable of handling radial loads and moderate axial loads in both directions. Heavy-duty series such as the 6300 range can support thrust loads up to 50 per cent of the bearing’s static radial load rating, making them suitable for more demanding conditions.
These popular metric bearings are manufactured from SAE 52100 (100Cr6) chrome steel, a material known for its high load capacity, durability and low noise performance. For applications where quiet operation and precision are critical, we recommend EZO brand bearings or our P6 low-noise, electric motor quality (EMQ) variants, available in the product variants below.
Material and temperature considerations
Chrome steel is favoured for its high load capacity and cost-effectiveness. These bearing types, equipped with a steel retainer and suitable lubricant, can operate at a constant temperature of 120°C or up to 150°C intermittently. However, beyond these temperatures, the load capacity of chrome steel decreases. For environments requiring higher temperature resistance or corrosion resistance, alternative materials should be considered.
For high-temperature or corrosive environments, bearings made from materials such as 440 grade stainless steel, marine grade 316 stainless steel, or ceramic are recommended. Chrome steel bearings are not suitable for use in corrosive environments as they lack corrosion resistance. The standard cage or retainer for these bearings is a two-piece ribbon type made from SPCC steel strip.
Because of the lack of corrosion resistance and temperature limits for this range, different materials should be chosen for very high temperatures or corrosive environments. Fortunately, SMB Bearings stocks corrosion resistant bearings and bearings for extreme temperatures in alternative materials for most sizes listed below such as 440 grade stainless steel, marine grade 316 stainless steel and ceramic.
Open popular metric bearings are supplied with oil lubrication. Shielded or sealed bearings are usually supplied with grease lubrication but shielded bearings can be lubricated with oil for low speed, low friction applications. Thanks to our in-house relubrication facility, open, shielded or sealed bearings can be offered with customer specified oils, greases or dry lubricants.
Get in touch with our specialist bearing team today by emailing sales@smbbearings.com or fill in the contact form.
How to measure ball bearings
Accurate measurement is essential when selecting or replacing a ball bearing. The correct dimensions ensure a proper fit, reliable performance and longer service life. Follow the steps below to measure your bearing correctly.
Key dimensions to measure
When measuring a ball bearing, three main dimensions are important:
- Inner diameter (ID or d): The bore size where the shaft fits
- Outer diameter (OD or D): The total diameter of the bearing’s outer ring
- Width (W or B): The overall thickness of the bearing from one side to the other
Bearings are usually specified in the format ID × OD × Width (for example, 10 × 26 × 8 mm).
Tools and preparation
- Use a vernier calliper or digital micrometre for precise measurements
- Ensure the bearing is clean and free from debris, as dirt can affect accuracy
- If the bearing is still installed, remove it carefully or measure through accessible points on the shaft or housing
Step-by-step measurement
- Measure the inner diameter (ID): Place the calliper jaws inside the bore and expand them until they contact the inner ring evenly
- Measure the outer diameter (OD): Close the jaws around the outside of the bearing’s outer ring and record the reading
- Measure the width (W): Position the calliper so the jaws touch both sides of the bearing and take the measurement
Additional considerations
- Many bearings have a reference number stamped on the side, which corresponds to their standard size and typ
- Check for suffix codes such as C3 or C4, which indicate special internal clearances
Note any shields or seals (e.g., ZZ, 2RS). Some bearings also have a flange on the outer ring
Why accurate measurement matters
Taking precise measurements ensures the bearing will fit the shaft and housing correctly, maintain the right clearance and operate efficiently. Incorrect sizing can cause vibration, premature wear, or bearing failure, making accurate measurement a key step in every bearing installation or replacement.
SMB Bearings offers a wide range of high-quality metric ball bearings suitable for various applications. Whether you need standard chrome steel bearings or specialised corrosion-resistant or high-temperature bearings, we have the correct bearing solution for you. Explore our product range to find the perfect bearing for your needs.
Ball bearing size chart
Click on INFO in the rows below to display technical drawings of the bearings with load and speed data. To ensure optimal performance and longevity, it is recommended to use these bearings at significantly less than their maximum load and speed ratings. These specifications are used for theoretical life calculations and help in selecting the right bearing for your needs.
Get in touch with our specialist bearing team today by emailing sales@smbbearings.com or fill in the contact form.
FAQs
- How do I identify a bearing?
- Do ball bearings have temperature limits?
- What is the advantage of a ball bearing without a retainer or cage?
- Can a ball bearing take axial load?
- Can ball bearings conduct electricity?
See product table below for dimensions and technical drawings
See products variants below for low noise options
