Product Overview

The NMT W 628/5-2RS1 is a double-sealed, single-row stainless steel miniature deep groove ball bearing. With a 5 mm bore, 11 mm outer diameter, and 4 mm width, this bearing is manufactured entirely from stainless steel (both rings and rolling elements) with a stainless steel stamped cage, equipped with contact rubber seals on both sides (2RS1) and pre-filled with high-quality grease. It integrates maintenance-free sealing, high corrosion resistance, compact design, and precision rotational accuracy into a single package, accommodating radial and bidirectional axial loads simultaneously.

 

The bearing offers a basic dynamic load rating of 0.403 kN (91 lbf) and a static load rating of 0.143 kN (32 lbf) . It achieves a limiting speed of 34,000 r/min. The bearing weighs only 0.0015 kg (1.5 g)  with an operating temperature range of -30°C to 120°C. The tolerance class is P0 (Normal/ABEC 1)  with CN radial clearance. Bore tolerance -0.008mm to 0, OD tolerance -0.008mm to 0, width tolerance -0.12mm to 0.

 

The 2RS1 double contact rubber seals are the key design feature – contact seals effectively prevent moisture, dust, and other contaminants from entering the bearing interior, and the bearing comes pre-lubricated from the factory for maintenance-free operation. The all-stainless steel construction provides excellent corrosion resistance and chemical resistance. The compact 5×11×4 mm dimensions make it ideal for space-constrained applications. The synergy of maintenance-free sealing, high corrosion resistance, compact design, and precision rotational accuracy makes this bearing the ideal bearing solution for miniature high-speed equipment.

 

Core Performance Advantages

1. Double Contact Rubber Seals – Maintenance-Free, Extended Life

The bearing features contact rubber seals on both sides (2RS1)  that effectively prevent moisture, dust, and other contaminants from entering the bearing interior. The bearing is pre-filled with high-quality grease at the factory and is maintenance-free – no washing or relubrication is required. This ensures stable temperature performance even at 34,000 r/min high speeds, while the integral sealing significantly prolongs bearing service life.

 

2. All-Stainless Steel Construction – High Corrosion Resistance, Extended Life

Manufactured entirely from stainless steel (rings, balls, and cage all stainless steel), this bearing provides excellent corrosion resistance and chemical resistance. In humid, corrosive, or high-cleanliness environments, stainless steel bearings effectively resist rust and chemical attack, significantly extending service life. This makes them particularly suitable for medical devices, food machinery, optical instruments, and semiconductor equipment with strict cleanliness and corrosion resistance requirements.

 

3. Compact Miniaturization – 5×11×4 mm

With compact dimensions – 5 mm bore, 11 mm outer diameter, and 4 mm width – this bearing can be easily integrated into space-constrained precision equipment. Weighing only 1.5 g, it is particularly suitable for miniature devices with space and weight requirements, such as precision instruments, miniature motors, and optical scanners.

 

4. 34,000 r/min High-Speed Performance – Industry-Leading

This bearing achieves a limiting speed of 34,000 r/min. The low-friction design and optimized internal geometry（shoulder diameter d₁ ≈ 6.81 mm, recess diameter D₂ ≈ 9.9 mm, chamfer r₁,₂ min. 0.15 mm）ensure stable operation and low heat generation at high speeds. This speed level makes it the ideal choice for high-speed miniature motors, precision instrument spindles, dental handpieces, and other high-speed miniature devices.

 

5. Deep Groove Design – Bidirectional Load Capacity, Excellent Versatility

Deep groove ball bearings feature a simple structure, wide versatility, and low friction. This bearing can accommodate radial loads and bidirectional axial loads simultaneously, providing excellent load capacity in miniaturized designs. With a dynamic load rating of 0.403 kN (91 lbf) and static load rating of 0.143 kN (32 lbf) , it meets the load requirements of most miniature applications.

 

6. Ultra-Lightweight – Only 1.5 Grams

The bearing weighs only 0.0015 kg (1.5 g) . The extremely low rotating mass effectively reduces centrifugal loads and inertia moments at high speeds.

 

7. P0 Normal Precision (ABEC 1) + CN Radial Clearance – Versatility and Reliability Combined

This bearing features P0 normal precision class (ABEC 1)  and CN normal radial internal clearance. Bore tolerance -0.008mm to 0, OD tolerance -0.008mm to 0, width tolerance -0.12mm to 0. This combination ensures reliable operation in the vast majority of general miniature applications, while facilitating easy installation and maintenance.

 

8. Wide Operating Temperature Range

This bearing operates within a temperature range of -30°C to 120°C, capable of adapting to various demanding environments from cold storage to high-temperature processing.

 

9. RoHS and REACH Compliant

This bearing is compliant with RoHS and REACH environmental standards, ensuring safe use even in regions with strict environmental regulations.

 

10. Clear Performance Specifications

 

Parameter Value

Bore d 5 mm

Bore Tolerance -0.008mm to 0

Outer Diameter D 11 mm

OD Tolerance -0.008mm to 0

Width B 4 mm

Width Tolerance -0.12mm to 0

Shoulder Diameter d₁ ≈ 6.81 mm

Recess Diameter D₂ ≈ 9.9 mm

Chamfer r₁,₂ min. 0.15 mm

Shaft da min. 6.2 mm

Shaft da max. 6.7 mm

Housing Da max. 10 mm

Max Fillet Radius ra max. 0.15 mm

Dynamic Load Rating C 0.403 kN (91 lbf)

Static Load Rating C₀ 0.143 kN (32 lbf)

Fatigue Load Limit Pu 0.006 kN

Limiting Speed 34,000 r/min

Minimum Load Factor kr 0.02

Calculation Factor f₀ 7.1

Ball Material Stainless Steel

Ring Material Stainless Steel

Cage Material 300 Series Stainless Steel

Seal Type Double Contact Rubber Seals (2RS1)

Tolerance Class P0 (Normal/ABEC 1)

Radial Clearance CN (Normal)

Lubrication Pre-filled Grease

Weight 0.0015 kg (1.5 g)

Temperature Range -30°C to 120°C

Typical Applications

The NMT W 628/5-2RS1, with its maintenance-free sealing, high-corrosion-resistance stainless steel material, and compact precision design, covers an exceptionally wide range of high-end miniature applications:

 

Food & Beverage Industry – processing equipment frequently exposed to water and other liquids

 

Chemical Processing – machinery exposed to aggressive chemicals

 

Marine Applications – environments with exposure to saltwater

 

Pharmaceuticals – equipment that must adhere to strict hygiene and cleanliness standards

 

Medical Devices – devices where non-corrosive properties are essential for long-term reliability

 

Precision Instruments – measuring devices, optical scanners, chromatography products

 

Small Electric Motors – cooling fans, miniature pumps, stepper motors

 

Optical Equipment – laser scanners, rotating mirrors, optical encoders

 

Semiconductor Manufacturing Equipment – precision wafer processing, chip packaging

 

Office Automation Equipment – printers, scanners

 

Household Appliances – internal combustion engines, home appliances

 

Industrial Machinery – gearboxes, instrumentation, agricultural machinery, construction machinery

 

Vehicles – automobiles, motorcycles, etc.

 

Consumer Products – inline skates, etc.

 

Important Installation Notes

✅ This bearing features double contact rubber seals (2RS1)  and comes pre-filled with high-quality grease – maintenance-free. Ready to install out of the box – no washing or relubrication required.

 

✅ This bearing is manufactured from all-stainless steel (rings, balls, and cage all stainless steel), offering excellent corrosion resistance, particularly suitable for humid, corrosive, or high-cleanliness environments.

 

✅ Ensure shaft and housing fits comply with P0 grade requirements. Shaft abutment diameter: da min. 6.2 mm, da max. 6.7 mm; housing abutment diameter: Da max. 10 mm; maximum chamfer radius: ra max. 0.15 mm.

 

✅ Due to the compact size (only 1.5 g), use specialized miniature bearing installation tools and take extra care to avoid excessive force or impact.

 

✅ Installation in a clean environment is recommended to prevent contaminant ingress that could affect high-speed performance.

 

⚠️ This bearing has no preload setting – if paired configurations or specific preload are required, adjust based on application requirements.

 

⚠️ This bearing has no lubrication groove and no relubrication feature – the rubber seal design is lubricated for life, requiring no relubrication.

 

NMT Quality Commitment

Japan NMT (Enmutī) has deep expertise in the precision bearing industry, with breakthroughs in material purification, process refinement, scenario customization, and intelligent upgrading, transforming precision bearings into core solutions addressing pain points across multiple industries. The NMT W 628/5-2RS1 bearing is manufactured to strict Japanese quality standards – from ring material (high-purity stainless steel) and rolling elements to superfinishing processes. The combination of all-stainless steel material (W series), double contact rubber seals (2RS1), compact miniature design, P0 precision class (ABEC 1), and CN radial clearance makes this bearing the flagship precision bearing in the NMT miniature bearing series – offering the perfect balance of maintenance-free sealing, high corrosion resistance, and precision performance.

 

Choose NMT W 628/5-2RS1 for:

 

✅ Double contact rubber seals – maintenance-free, extended life

 

✅ All-stainless steel material – high corrosion resistance, extended life

 

✅ Compact miniaturization – 5×11×4 mm, only 1.5 g

 

✅ 34,000 r/min high-speed performance – industry-leading

 

✅ Deep groove design – bidirectional load capacity, low friction, low noise

 

✅ 300 series stainless steel cage – low friction, high speed

 

✅ Wide temperature range – -30°C to 120°C

 

✅ RoHS and REACH compliant

 

✅ Factory pre-lubricated – ready to install

 

✅ Japanese precision manufacturing quality