1 Complete Model & Code Explanation

Model：W 628/6 R-2Z

Code Definition

W：Stainless steel series with basic rust prevention and mild corrosion resistance

628/6 R：Non-standard dimension specification of miniature deep groove ball bearing

2Z：Double-side steel shield, non-contact protection structure

Structure：Closed structure with steel shields mounted on both ends

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

Important reminder: W 628/6 R-2Z is stainless steel miniature bearing with 2Z steel shields. Non-contact steel shields feature low friction torque and higher limiting speed compared with equivalent 2RS1 rubber sealed bearings. However, steel shields can only block dry dust without resistance against mist or liquid splash, so it is not recommended for humid or splash-prone conditions. Steel shields are non-detachable; prying shields open for cleaning is forbidden. Continuous moisture penetration leads to rolling element rust. Stainless steel is softer than bearing steel, avoid impact scratches during assembly to prevent corrosion initiation points.

Basic Parameters

Bore d：6 mm

Outer diameter D：16 mm

Width B：6 mm

Bearing type：Single-row deep groove ball bearing

Number of rows：Single row

Bore form：Straight cylindrical bore

Seal arrangement：2Z, double-side non-contact steel shield

Cage：Stamped stainless steel cage

Material：Stainless steel

Surface coating：Uncoated

Pre-installed lubricant：General long-service grease

Relubrication capability：On-site re-greasing unavailable

Radial internal clearance：Normal clearance class

Duplex arrangement：Not supported, single unit operation only

Basic dynamic load rating：0.061 kN

Basic static load rating：0.022 kN

Reference speed：62 000 r/min

Limiting speed：43 000 r/min

Net weight：0.00025 kg

Indicative carbon footprint：0.00055 kg CO₂e

eClass code：23-05-08-01

UNSPSC code：31171504

Series Suffix Comparison

W 628/6 R：Open stainless steel bearing without shield

W 628/6 R-2Z：Stainless steel double steel shield, high speed, dust-only protection (this model)

W 628/6 R-2RS1：Stainless steel double contact rubber seal, dust & mist resistance, relatively lower speed

W 628/6 R-2RS1/VT378：Stainless steel rubber seal filled with food-grade grease

2 Structure & Operating Characteristics

Japan NMT W 628/6 R-2Z is developed based on W-series stainless steel miniature bearing platform, equipped with double-side non-contact 2Z steel shields. Tiny clearance exists between shields and inner ring without contact, resulting in low friction loss and stable high-speed operation. Stainless steel matrix resists mild ambient moisture and reduces rust risk, yet clearance cannot block mist and liquid.

The bearing mainly supports radial loads and withstands limited bidirectional axial loads. Without rubber components, there is no risk of rubber aging under short-term temperature rise, suitable for light high-speed rotary parts with transient heat. It should be noted that in high humidity environments, moisture can penetrate through shield gaps gradually. Long-term humid service causes grease emulsification and rolling element rust, continuous operation under mist conditions is not advised.

3 Core Performance Advantages

1. W-series stainless steel material delivers superior rust resistance vs standard bearing steel miniature bearings against dry ambient moisture.

2. Double-side non-contact 2Z steel shields create low rotational friction, enabling higher limiting speed than same-size rubber sealed bearings.

3. Free of rubber components, eliminating risks of rubber aging and swelling failure, better adaptability for short-time elevated temperature.

4. Compact overall dimension, non-standard size fits various small lightweight high-speed transmission devices.

5. Factory pre-filled long-life grease enables long-term maintenance-free operation under clean and dry working conditions.

6. Symmetrical shielding structure without assembly orientation restriction, compatible with automatic assembly production lines.

4 Typical Application Fields

4.1 Micro Motors & Handheld Tools

Rotary shafts of small high-speed micro motors, rotating assemblies of portable mini power tools.

4.2 Camera Gimbals & Model Equipment

Mini aerial gimbals, high-speed drive wheels for RC models, damping rotary shafts of compact gimbals.

4.3 Office Automation Equipment

Inner rollers of compact printers and scanners, miniature transmission mechanisms for office devices.

4.4 Precision Instruments for Dry Environment

Test tooling inside laboratory drying ovens, rotary shafts of inspection instruments operated under dry conditions.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Maintain clean and dry assembly environment and minimize suspended dust. Press force must act only on ring end faces. Knocking steel shields is prohibited to avoid deformation and abnormal clearance. Stainless steel has low hardness; prevent surface impact scratches which become corrosion sources. Symmetrical shielding design requires no specific installation direction. Never pry steel shields outward; deformation permanently weakens dust protection.

5.2 Selection Guidance

Dry environment, high speed priority, only dry dust present → W 628/6 R-2Z (this model)

Mist, intermittent liquid splash, enhanced sealing required → W 628/6 R-2RS1

Humid working condition with food contact requirements → W 628/6 R-2RS1/VT378

Long-term immersion or high condensation environment → This model not recommended, adopt fully rubber sealed bearing solution

5.3 Lubrication Instruction

Pre-filled with general long-service grease at factory for maintenance-free service under dry and clean conditions. 2Z steel shields provide simple protection only. Forcible shield dismantling and solvent flushing are strictly prohibited; dismantled shields cannot be restored and protective capacity will be permanently reduced. Prolonged high temperature accelerates grease oxidation and drying, shortening bearing service life.

5.4 Environmental Application Notes

2Z non-contact shields only block dry solid dust and cannot resist mist, steam or liquid splash. Stainless steel offers basic rust resistance but is not rust-proof. Persistent high humidity allows moisture to enter via shield gaps, triggering rust and grease failure. This bearing is unsuitable for workstations with water spray or heavy condensation.

6 Daily Maintenance & Fault Troubleshooting

Carry out low-speed running-in after assembly, confirm no abnormal noise and temperature rise before gradually raising to operating speed. Common faults: abnormal noise during high-speed rotation, rotational seizure, continuous temperature rise, internal rust and jamming.

Typical failure causes: massive dust penetrating shield gaps; long-term overspeed operation; moisture ingress and rolling element rust under continuous high humidity; shield deformation caused by assembly extrusion. Bearings with rust or persistent jamming noise cannot be repaired and replacement is recommended.