1 Complete Model & Code Explanation

Model：625-2Z/C3

Code Definition

625：Basic dimension of miniature single-row deep groove ball bearing

2Z：Double-side pressed steel non-contact shield

C3：Increased radial internal clearance class

Structure：Riveted steel shields installed on both ends of bearing

Supply form：Single independent bearing, no factory duplex grinding, DB/DF duplex arrangement not supported

Important reminder: 625-2Z/C3 is standard raceway bearing steel miniature bearing, capable of bearing radial loads and moderate bidirectional axial loads. 2Z steel shields adopt clearance non-contact structure, featuring low running resistance and superior speed performance compared with 2RS/2RZ rubber sealed bearings. It only blocks dry coarse dust, unable to isolate water vapor, oil mist and fine particles. Steel shields are permanently riveted; dismantling and cleaning are forbidden, and on-site grease replenishment is not allowed. This is standard 625 bearing. Compared with E2 optimized raceway version, it has higher cost performance and suits mass general supporting applications.

Basic Parameters

Bore d：5 mm

Outer diameter D：16 mm

Width B：5 mm

Bearing type：Single-row deep groove ball bearing

Number of rows：Single row

Bore form：Straight cylindrical bore

Seal arrangement：2Z double pressed steel non-contact shield

Cage：Stamped steel cage

Radial internal clearance：C3 increased clearance

Material：Bearing steel

Surface coating：Uncoated

Pre-installed lubricant：General long-service grease

Relubrication capability：On-site re-greasing unavailable

Duplex arrangement：Not supported, single unit operation only

Basic dynamic load rating：0.084 kN

Basic static load rating：0.034 kN

Reference speed：82 000 r/min

Limiting speed：56 000 r/min

Net weight：0.00025 kg

Indicative carbon footprint：0.00060 kg CO₂e

eClass code：23-05-08-01

UNSPSC code：31171504

Series Suffix Comparison

625：Open type without protection, highest limiting speed, no dust resistance

625-Z/C3：Single steel shield, C3 clearance

625-2Z/C3：Double steel shield, standard raceway, C3 increased clearance (this model)

E2.625-2Z/C3：E2 low-vibration optimized raceway, double shield with C3 clearance, better noise and durability performance

625-2RZ：Double non-contact rubber seal, stronger dust resistance, slightly lower speed

625-2RS：Double contact rubber seal, slight moisture resistance, lowest allowable speed

2 Structure & Operating Characteristics

Japan NMT 625-2Z/C3 is built on mature universal 625 dimension platform with standard deep groove raceway profile, double-side 2Z pressed steel shields and C3 increased radial clearance, developed for mass-production general miniature rotary mechanisms. The well-proven standard raceway geometry delivers stable load capacity and high interchangeability.

A tiny clearance exists between steel shields and inner ring without contact friction to guarantee high rotating speed. However, the clearance structure leads to limited protection; dust and moisture can penetrate slowly under dusty and humid conditions. C3 increased clearance is designed for continuous high-speed operation, absorbing thermal expansion of shaft system and preventing bearing seizure caused by insufficient clearance. Stamped steel cage is lightweight with good centrifugal stability, suitable for medium and small high-speed rotating components. The bearing mainly bears radial loads and withstands certain bidirectional axial loads. Long-term overspeed operation is prohibited.

3 Core Performance Advantages

1. Mature standard raceway structure with excellent versatility, directly interchangeable with all 625-size bearings for convenient procurement and assembly.

2. Non-contact design of double-side 2Z steel shields brings low friction loss; limiting speed exceeds rubber sealed bearings.

3. C3 increased radial clearance perfectly adapts to high-speed temperature rise and prevents thermal seizure.

4. All-metal shielding components contain no rubber parts, free from rubber aging, applicable to medium-high temperature environment with clean condition.

5. Symmetrical shielding structure on both ends with no installation orientation required, simplifying automatic assembly process.

6. Standard construction has prominent cost advantages, ideal for mass production matching of general equipment.

4 Typical Application Fields

4.1 Small High-Speed Motors & Cooling Components

Mini cooling fans, small brushless motors, portable air pump motors.

4.2 Office & Automation Conveying Parts

Printer guide rollers, small conveyor idlers, automation micro rotary shafts.

4.3 Model & Light-Duty Transmission Mechanisms

RC model spindle transmission, rotary assemblies of small electric toys.

4.4 Simple Inspection & Small Instruments

Inspection gimbal shafts, rotary axles of portable devices, light laboratory auxiliary mechanisms.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Keep assembly area clean to avoid hard impurities entering the bearing. Press force shall only act on end faces of bearing rings. Knocking or prying steel shields is strictly prohibited to prevent shield deformation and clearance deviation. Excessive interference fit should be avoided when adopting C3 clearance model, otherwise the advantage of increased clearance will be eliminated. Symmetrical double-shield structure requires no specific installation direction.

5.2 Selection Guidance

Highest speed priority & extremely clean environment → 625 open bearing

Single-side dust protection, general dry high-speed scenario → 625-Z/C3

Mass general matching, dry clean environment, coarse dust protection on two sides → 625-2Z/C3 (this model)

Strict requirement on vibration & noise, long continuous operation → Upgrade to E2.625-2Z/C3

Fine dust exists, enhanced dust protection needed → Choose 2RZ non-contact rubber sealed bearing

Working environment with water vapor, oil mist or minor water splash → Choose 2RS contact rubber sealed bearing

5.3 Lubrication Instruction

Pre-filled with standard long-service grease at factory, supporting long-term maintenance-free operation under standard dry and clean conditions. 2Z steel shields are riveted closed structure. Dismantling shields, cleaning with organic solvent and on-site grease filling are strictly forbidden. Long-term overspeed and continuous high temperature accelerate grease oxidation and drying, greatly shortening bearing service life.

5.4 Environmental Application Notes

2Z steel shields can only block dry coarse solid debris, incapable of isolating fine dust, water vapor, oil mist and liquid water. Bearing steel does not have inherent rust-proof property. Even with double-side shields, internal rust may easily occur under high humidity. Sealed bearings must be selected for humid working conditions. No rubber parts mean no rubber aging risk, yet internal lubricant will gradually fail under prolonged high temperature.

6 Daily Maintenance & Fault Troubleshooting

Carry out low-speed running-in test after assembly. Gradually raise speed to rated working speed only after confirming no abnormal noise and temperature rise. Typical faults of this model: continuously increasing running noise, rotation jamming, abnormal temperature rise.

Common failure causes: internal raceway abrasion due to continuous fine dust intrusion; grease drying caused by long-time high temperature; insufficient clearance resulting from improper fitting tolerance; excessive sustained axial load. Once raceway pitting or cage deformation appears, the bearing cannot be repaired and replacement is recommended.