1 Complete Model & Code Explanation

Model: W 628/5-2RS1

Code Definition

W：Stainless steel series identifier

628/5：Basic dimension of miniature deep groove ball bearing

2RS1：Double contact-type rubber seals

Structure：Double rubber contact seals, no metal shields

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

Important reminder: W 628/5-2RS1 is stainless steel miniature bearing with double contact rubber seals, suitable for radial loads and moderate bidirectional axial loads. Compared with 2Z metal shields, 2RS1 contact seals provide much better resistance to moisture and oil contamination. However, contact friction from sealing lips reduces limiting speed versus open and 2Z variants. Pre-greased at factory for maintenance-free service under normal conditions; seals are non-detachable for re-lubrication. Continuous liquid immersion and strong chemical corrosion environments are not applicable.

Basic Parameters

Bore d：5 mm

Outer diameter D：11 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：2RS1, double contact rubber seals

Oil groove：Without oil groove

Outer ring locating feature：No locating groove or shoulder

Cage：Stamped stainless steel cage

Radial internal clearance：CN standard clearance

Material：Stainless steel

Surface coating：Uncoated

Pre-installed lubricant：Long-life grease pre-filled at factory

Relubrication capability：On-site re-greasing unavailable

Duplex arrangement：Not supported, single unit operation only

Basic dynamic load rating：0.082 kN

Basic static load rating：0.040 kN

Reference speed：68 000 r/min

Limiting speed：44 000 r/min

Net weight：0.00015 kg

Indicative carbon footprint：0.00052 kg CO₂e

eClass code：23-05-08-01

UNSPSC code：31171504

Series Suffix Comparison

W 628/5：Open type, maximum rotational speed, no protection

W 628/5-Z：Single metal shield, only blocks dry dust

W 628/5-2Z：Double metal shields, basic dust protection, poor moisture resistance

W 628/5-2RS1：Double contact rubber seals (this model), dust & moisture resistant, moderate friction

628/5-2RS1 (without W)：Bearing steel version, similar load capacity, no anti-corrosion property

2 Structure & Operating Characteristics

Japan NMT W 628/5-2RS1 is W-series stainless steel miniature deep groove ball bearing equipped with double low-friction contact rubber seals 2RS1, developed for miniature precision transmissions requiring protection against moisture and light oil mist. Fully stainless steel construction delivers reliable rust resistance compared to bearing steel versions, suitable for equipment with floating dust, mild humidity and light oil mist.

Adopts integrated stamped stainless steel cage to stabilize ball motion and suppress high-speed vibration and noise. The flexible lip of 2RS1 rubber seal contacts the inner ring surface, effectively blocking dry dust, moisture and light oil mist. Protection level is higher than non-contact metal shields, while rotational friction torque rises and maximum allowable speed decreases accordingly. Long-life grease is pre-sealed inside upon manufacturing; seals cannot be removed for cleaning or re-lubrication. Standard CN radial clearance matches assembly tolerances of most miniature shafts.

The bearing mainly withstands radial loads and tolerates moderate bidirectional axial loads. Long-term liquid immersion and persistent exposure to corrosive solvents are prohibited, which will cause seal aging and raceway corrosion.

3 Core Performance Advantages

1. Miniature dimension 5×11×5 mm, ideal for precision transmission structures with limited installation space.

2. W-series stainless steel substrate with stable rust resistance for humid and lightly condensed environments.

3. Double 2RS1 contact rubber seals offering protection against dust, moisture and light oil mist, superior to 2Z metal shields.

4. Factory pre-filled special grease for long maintenance-free operation under standard working conditions.

5. Stamped stainless steel cage with lightweight stable structure for continuous operation of miniature bearings.

6. CN standard radial clearance provides high interchangeability for direct replacement of same-size bearings.**

7. Contact seal balances protection capacity and rotational speed, suitable for equipment cavities that cannot be fully sealed.

4 Typical Application Fields

4.1 Precision Small Drive Motors

Miniature fan motors, built-in instrument drive motors, rotating spindles of beauty portable devices.

4.2 Handheld Portable Power Tools

Compact grinding assemblies, miniature drive spindles, portable precision actuators.

4.3 Tiny Medical Instruments

Transmission assemblies of minimally invasive devices, rotary mechanisms of compact testing instruments, portable medical sensing equipment.

4.4 Automation & Intelligent Equipment

Miniature encoders, spindles for compact automation fixtures, transmission units of consumer smart devices.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Assemble in clean surroundings to prevent hard particles scratching rubber sealing lips. Never strike bearing end faces or seal areas directly. Apply uniform pressing force with proper sleeves to avoid seal extrusion deformation and adhesive separation. Strictly control interference fit between shaft and housing. Excessive interference reduces internal clearance, raises operating temperature at high speed and accelerates rubber aging. Store bearings away from strong light and high temperature to delay seal deterioration.

5.2 Selection Guidance

Fully sealed dust-free housing, maximum speed priority → W 628/5 open type

Only dry floating dust exists, no moisture protection needed → W 628/5-2Z double shield variant

Exposed to humidity and light oil mist, comprehensive dust & moisture protection required → W 628/5-2RS1 (this model)

Dry indoor environment without anti-rust demand, cost optimization → 628/5-2RS1 bearing steel version

5.3 Lubrication Instruction

Special long-life grease is hermetically pre-filled inside the bearing for long service without maintenance under normal conditions. Seals are crimped and non-detachable, on-site re-greasing is impossible. Prolonged high temperature and continuous overspeed operation accelerate grease deterioration and rubber aging, drastically shortening service life. Do not soak bearings in strong solvents; solvents will corrode rubber seals and dissolve built-in lubricant.

5.4 Environmental Application Notes

2RS1 contact rubber seals resist dust, moisture and light oil mist, but cannot endure long-term liquid immersion, high-pressure water washing or heavy chemical attack. Long chemical exposure leads to seal swelling, hardening and failure. Stainless steel only provides basic rust resistance; corrosion will still occur under continuous water accumulation.

6 Daily Maintenance & Fault Troubleshooting

Carry out short low-speed running-in after assembly; increase to rated speed only after confirming no abnormal noise and excessive temperature rise. Typical faults of 2RS1 sealed miniature bearings: increased rotation torque, abnormal operating noise, persistent overheating, grease leakage.

Common failure causes: sealing lip abrasion by hard foreign particles, long-term penetration of moisture/oil mist, rubber aging due to sustained overheating, insufficient clearance caused by improper assembly, prolonged excessive axial load. Damaged seals or corroded/worn raceways cannot be repaired; replacement with new bearing is recommended upon failure.