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604 Deep Groove Ball Bearing 4x12x4mm
At 4mm bore and 12mm OD, the 604 bearing is the smallest standard deep groove ball bearing in the 4mm-shaft class. When a design calls for a bearing that fits inside a 12mm housing bore on a 4mm shaft, the 604 bearing is the only standard catalog option.
Key Specifications
- Sealing: Open, ZZ (metal shields), 2RS (NBR rubber contact seals). ZZ retains full rated speed.
- Speed and Load: 0.96 kN dynamic (Cr), 0.37 kN static (Cor). 48,000 RPM open/ZZ; 38,000 RPM with 2RS seals.
- Axial Load: Supports 8-10% of radial rating in CN clearance. Approximately 0.08-0.10 kN sustained.
- Temperature: -40 to 120 C with standard grease. High-temperature polyurea options extend to 150 C.
- Material and Precision: GCr15 bearing steel (AISI 52100 equivalent). ABEC-3 standard; ABEC-5 and ABEC-7 available.
For any inquiries, please contact with our Supporting Team at sales@yuanhecd.com.
| Model | 604 |
| Bore (d) | 4 mm |
| OD (D) | 12 mm |
| Width (B) | 4 mm |
| Type | Open / Shielded / Sealed |
| ABEC | ABEC-3 |
| Material | GCr15 bearing steel (AISI 52100) |
| Dynamic Load Cr | 0.96 kN |
| Static Load Cor | 0.37 kN |
| Max Speed | 48,000 RPM (open/ZZ) 38,000 RPM (2RS) |
| Temperature | -40 to 120 C |
Bore x OD x Width
4 x 12 x 4 mm
Dynamic Load Cr
0.96 kN
Static Load Cor
0.37 kN
Max Speed
48,000 RPM
Sealing
Open / ZZ / 2RS
Precision
ABEC-3
Shielding and Lubrication
The 604 ZZ bearing uses non-contact SPCC steel shields pressed into the outer ring. At 12mm OD and 48,000 RPM, surface velocity at the shield edge is approximately 30 m/s. The factory-set labyrinth clearance is calibrated for this velocity and remains stable because the 12mm shield diameter resists centrifugal distortion. Each bearing ships at 25-35% fill with lithium soap grease. Given the small grease volume at this bearing size, the initial fill covers the full service life under light to moderate loads without regreasing.
The 604 2RS bearing variant uses nitrile contact seals. At 4mm width, the seal lip contact area is small, limiting friction torque increase to approximately 10-15% over the open bearing. The 2RS seal reduces maximum speed to 38,000 RPM. For miniature bearings at this scale, the 2RS configuration is effective for dust and moisture protection in consumer electronics and handheld instruments where the bearing cannot be accessed for cleaning or relubrication during the product lifetime.
Performance
At 0.96 kN dynamic and 0.37 kN static, the 604 bearing is rated for light-duty applications. The 624 bearing (4x13x5mm, 1.31 kN Cr) adds 1mm OD and 1mm width for 36% more capacity. The 634 bearing (4x16x5mm, 1.73 kN) adds 4mm OD and 1mm width for 80% more capacity. Select the 604 bearing when 12mm OD is the absolute limit. If the housing bore can accept 13mm, the 624 bearing provides extra capacity for the same shaft. If 16mm OD fits, the 634 bearing delivers nearly double the dynamic load rating.
At 4mm bore, the shaft itself becomes the limiting factor for load capacity at these bearing ratings. A 4mm shaft in common alloy steel yields at approximately 3-4 kN in bending, so the 0.96 kN bearing rating is the governing limit only for pure radial loads with a short shaft overhang. For cantilevered loads where bending moment at the shaft root is significant, the shaft strength rather than bearing capacity determines the allowable load. The 604 bearing fits deep groove ball bearing applications where OD space is the binding constraint.
OEM and Customization
Yuanhe manufactures the 604 bearing to customer specifications. Common OEM customizations include C2 clearance for preloaded micro-spindle and gyroscope assemblies, stainless steel (AISI 440C) rings and balls for dental and surgical handpieces requiring autoclave sterilization, and low-noise polyurea grease for consumer electronics where bearing tone above 25 dB is objectionable. Cage materials include stamped steel and glass-reinforced polyamide. Standard lead time is 7 to 15 days. Submit drawings or existing part numbers for a quote, or contact Yuanhe directly.
Applications
Dental and surgical handpiece turbines
Optical encoder and gyroscope gimbals
Miniature cooling fans for portable electronics
Micro-drones and model aircraft actuators
Laboratory micro-centrifuge rotors
Wristwatch automatic winding mechanisms
Fiber optic alignment stages
Microfluidic pump stepper drives
Hearing aid and wearable device micro-motors
Frequently Asked Questions
What is the smallest standard bearing that fits a 4mm shaft and 12mm housing bore? +
The 604 bearing (4x12x4mm) is the standard catalog bearing for this envelope. No other standard deep groove ball bearing combines a 4mm bore with a 12mm OD. The next standard size up is the 624 bearing at 13mm OD, which requires a slightly larger housing bore. If the 12mm housing bore is an existing machined dimension that cannot be changed, the 604 bearing is the standard solution without custom tooling.
Can a 604 bearing survive autoclave sterilization cycles? +
Standard 604 bearings with GCr15 steel rings and lithium soap grease are not rated for autoclave conditions (121-134 C saturated steam). For autoclave compatibility, Yuanhe supplies the 604 bearing with AISI 440C stainless steel rings and balls, paired with perfluoropolyether (PFPE) grease rated to 200 C. This combination resists corrosion from steam exposure and maintains lubrication film after repeated sterilization cycles. For dry-heat sterilization above 200 C, specify all-ceramic bearings with no organic grease.
What is the maximum practical speed for a 604 bearing in a dental handpiece turbine? +
Dental handpiece turbines typically operate the 604 bearing at 300,000-400,000 RPM, well above the standard grease-lubricated reference speed of 48,000 RPM. At these speeds, oil-mist or air-oil lubrication is mandatory, and the bearing must be a hybrid ceramic configuration (Si3N4 balls with steel or ceramic rings). The standard 604 bearing is not rated for handpiece turbine speeds. Contact Yuanhe with your target RPM, duty cycle, and lubrication method for a turbine-bearing specification recommendation.
How does shaft strength limit the 604 bearing in a cantilevered load application? +
A 4mm shaft in alloy steel yields at approximately 3-4 kN in pure bending. In a cantilevered arrangement, the bending moment at the shaft root is the product of radial load and overhang distance. For a 10mm overhang, a 0.3 kN radial load produces a bending stress near the yield point. The 604 bearing itself is rated to 0.96 kN Cr, but in cantilevered applications the shaft typically fails before the bearing. Design the shaft diameter and overhang to keep bending stress below the material fatigue limit at the expected load cycles.
