Home > 628 Deep Groove Ball Bearing 8x24x8mm

628 Deep Groove Ball Bearing 8x24x8mm

At 8mm bore and 24mm OD, the 628 is the largest bearing in the miniature deep groove family below 10mm bore. When the 627 bearing reaches its load limit in an 8mm shaft design, the 628 bearing adds the cross-section needed for higher radial and axial capacity.

Key Specifications

Sealing: Open, ZZ metal-shielded, or 2RS double rubber-sealed configurations for every protection level.
Speed and Load: 32,000 RPM (open/ZZ), 4.00 kN dynamic load, 2.00 kN static load at standard CN clearance.
Operating Direction: Designed for radial loads. Deep groove geometry supports moderate bidirectional axial loads.
Temperature Range: -40 to 120 C with NBR seals and standard lithium grease. Wider with alternate seal materials.
Material and Precision: GCr15 bearing steel (AISI 52100), ABEC-3 as standard. 100% dimensional inspection included.

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628 Bearing Technical Specifications

Model	628
Type	Open / Shielded / Sealed
Bore Dia. (d)	8 mm
Outside Dia. (D)	24 mm
Width (B)	8 mm
Dynamic Load Cr	4.00 kN
Static Load Cor	2.00 kN
Max Speed	32,000 RPM (open/ZZ) 18,000 RPM (2RS)
Material	GCr15 bearing steel (AISI 52100)
ABEC	ABEC-3
Temperature	-40 to 120 C

Bore x OD x Width

8 x 24 x 8 mm

Dynamic Load Cr

4.00 kN

Static Load Cor

2.00 kN

Max Speed

32,000 RPM

Sealing

Open / ZZ / 2RS

Precision

ABEC-3

Shielding and Lubrication

The 628 bearing is available in open, ZZ, and 2RS configurations. Open bearings integrate into oil-bath or circulating-oil systems. ZZ metal shields use non-contact steel covers pressed into the outer ring, retaining factory grease while preserving the full 32,000 RPM speed rating.

2RS rubber seals employ nitrile (NBR) contact lips on the inner ring shoulder, blocking moisture and fine dust at the cost of reduced maximum speed (approximately 18,000 RPM). Unlike smaller bearings in the 6mm and 7mm bore classes, the 628 bearing has sufficient radial cross-section for the 2RS seal lip to track reliably without excessive side loading on the rolling elements.

Performance

The 628 bearing delivers 4.00 kN dynamic load and 2.00 kN static load. Compared to the 627 bearing (7x22x7mm, 3.35 kN Cr), the 628 bearing adds 19% more dynamic capacity through a 2mm OD increase and 1mm wider cross-section. The 8mm width also improves axial load distribution: the 628 bearing handles roughly 15% of its dynamic radial rating as axial load, compared to 10-12% for narrower miniature bearings.

ABEC-3 precision is standard. ABEC-5 is available for spindle and instrumentation applications where radial runout control is the primary specification driver.

OEM and Customization

Yuanhe supplies the 628 bearing with full customization for volume orders. Standard internal clearance is CN. Non-standard clearances (C2, C3, C4) are available for press-fit or thermal growth conditions. Grease options range from standard lithium soap to low-noise ester grease and high-temperature polyurea.

Cage materials include stamped steel, glass-reinforced polyamide, and machined brass. Submit your specification sheet or drawing for a quote.

Applications

Brushless DC motor stators and rotors

Industrial cooling fans and blowers

Conveyor roller idlers

Electric power steering assist motors

Small gear pumps and hydraulic assist units

Hobby and light industrial gearboxes

Textile spinning spindles

HVAC damper actuators

Frequently Asked Questions

How does the 628 bearing compare to the 627 bearing when both fit an 8mm shaft? +

The 628 bearing (8x24x8mm, 4.00 kN Cr) provides 19% more dynamic capacity and 43% more static capacity than the 627 bearing (7x22x7mm, 3.35 kN Cr). If your 8mm shaft design currently uses a 627 bearing and shows signs of overload, upgrading to the 628 bearing requires no shaft change. Note that the 628 bearing is 1mm wider; verify housing width before substituting.

What axial load can a 628 deep groove ball bearing support? +

A 628 bearing in standard CN clearance handles axial loads up to approximately 15% of its dynamic radial rating: about 0.6 kN sustained. Axial capacity increases with radial clearance. A C3 clearance 628 bearing can accept roughly 20% of Cr (0.8 kN). For pure thrust applications, specify an angular contact or thrust bearing instead.

What cage material is best for a 628 bearing running above 20,000 RPM? +

For sustained operation above 20,000 RPM, a machined brass cage is recommended. Brass dissipates heat better than stamped steel and resists centrifugal deformation. Glass-reinforced polyamide cages reduce rotating mass for start-stop cycles but are limited to 120 C continuous. Stamped steel cages are sufficient below 15,000 RPM.

Can a 628 bearing be used with oil-mist lubrication instead of grease? +

Yes. The 628 bearing in open configuration supports oil-mist lubrication. Oil-mist systems deliver a controlled aerosol of ISO VG 32 or VG 46 oil directly to the rolling elements, removing heat more effectively than grease. This extends the speed limit to approximately 38,000 RPM. Contact Yuanhe with your duty cycle for a lubrication recommendation.