Product Overview

The NMT D/W R144 R is a flanged, ultra-miniature stainless steel deep groove ball bearing. With a 3.175 mm (0.125 in) bore, 6.35 mm (0.25 in) outer diameter, and 2.38 mm (0.0937 in) width, this bearing is manufactured entirely from stainless steel (both rings and rolling elements) with a stainless steel stamped cage, and features an integral flange on the outer ring (R suffix). It integrates flanged convenience, extreme miniaturization, ultra-high speed, corrosion resistance, and precision rotational accuracy into a single package, accommodating radial and bidirectional axial loads simultaneously.

 

The bearing offers a basic dynamic load rating of 0.163 kN (37 lbf) and a static load rating of 0.048 kN (11 lbf). It achieves a reference speed of 170,000 r/min and a limiting speed of 100,000 r/min. The bearing weighs only 0.0003 kg (0.3 g) with an operating temperature range of -30°C to 120°C.

 

The flanged (R) design is the most prominent structural feature of this bearing – the integral flange on the outer ring (flange outer diameter 0.29598 in / ≈7.52 mm, flange thickness 0.02299 – 0.023 in) enables direct axial location without the need for additional retaining rings or circlips, significantly simplifying installation and saving axial space. This bearing features an open design (unsealed) – lubrication must be selected based on application requirements.

 

Model Code Decoding – Understanding NMT D/W R144 R

Code Meaning

D/W Inch series designation – miniature bearing series designed with inch dimensions

R144 Basic model – R indicates flanged outer ring for easy axial location and mounting

144 Size code – 1/8 inch bore, 1/4 inch outer diameter

Core Value: The R flanged design enables direct axial location through the flange, eliminating the need for additional retaining rings or circlips, significantly simplifying installation and saving space. The W-series stainless steel material provides excellent corrosion resistance and chemical resistance. The D/W inch series design delivers stable load capacity within an ultra-small 3.175 mm bore. The stainless steel stamped cage ensures reliable rolling element guidance at ultra-high speeds. The P0 normal precision class (ABEC 1) combined with CN radial internal clearance ensures low friction, low vibration, and low noise operation even at the 100,000 r/min limiting speed. This bearing features a single-row open design with a cylindrical bore and a flanged outer ring. The synergy of flanged convenience, extreme miniaturization, ultra-high speed, and stainless steel corrosion resistance makes this bearing the ideal bearing solution for miniature high-precision equipment.

 

Core Performance Advantages

1. Flanged Design (R) – Easy Installation, Space Saving

The integral flange on the outer ring (R) is the most prominent structural advantage of this bearing:

 

Simplified axial location: The flange directly mates with the housing face – no additional retaining rings or circlips required

 

Space saving: Eliminates the need for locating shoulders on the shaft or in the housing

 

Quick installation: Direct press-fit into the housing completes location, significantly reducing assembly time and cost

 

High reliability: Precise flange location ensures accurate axial clearance control

 

2. Extreme Miniaturization – Only 3.175×6.35×2.38 mm

With a bore of only 3.175 mm (0.125 in), outer diameter of only 6.35 mm (0.25 in), and width of only 2.38 mm (0.0937 in), weighing just 0.0003 kg (0.3 g), this bearing is one of the smallest standardized precision bearings in the world. Flange outer diameter 0.29598 in (≈7.52 mm), flange thickness 0.02299 – 0.023 in. It is particularly suitable for applications with extreme space constraints.

 

3. 100,000 r/min Ultra-High Speed – Industry-Leading Performance

This bearing achieves a reference speed of 170,000 r/min and a limiting speed of 100,000 r/min. The low-friction design and optimized internal geometry（shoulder diameters d₁ ≈ 3.93 mm, D₁ ≈ 5.38 mm, chamfer r₁,₂ min. 0.1 mm）ensure stable operation and low heat generation at extreme speeds.

 

4. Stainless Steel Material – 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.

 

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. Dynamic load 0.163 kN (37 lbf) , static load 0.048 kN (11 lbf), meeting the load requirements of most miniature applications.

 

6. Ultra-Lightweight – Only 0.3 Grams

The bearing weighs only 0.0003 kg (0.3 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 -0.00019″ to +0.00019″ , OD tolerance -0.0007″ to -0.00031″ , width tolerance -0.005″ to 0″. This combination ensures reliable operation in the vast majority of general miniature applications, while facilitating easy installation and maintenance.

 

8. Open Design – Flexible Lubrication Options

This bearing features an open design (unsealed), allowing flexible selection of lubrication methods based on application – grease lubrication for general high-speed applications, oil-mist or oil-air lubrication for extreme high-speed machining.

 

9. Wide Operating Temperature Range

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

 

10. Clear Performance Specifications

 

Parameter Value

Bore d 3.175 mm (0.125 in)

Bore Tolerance -0.00019" to +0.00019"

Outer Diameter D 6.35 mm (0.25 in)

OD Tolerance -0.0007" to -0.00031"

Width B 2.38 mm (0.0937 in)

Flange Outer Diameter 0.29598 in (≈7.52 mm)

Flange Thickness 0.02299 – 0.023 in

Shoulder Diameter d₁ ≈ 3.93 mm

Shoulder Diameter D₁ ≈ 5.38 mm

Chamfer r₁,₂ min. 0.1 mm

Dynamic Load Rating C 0.163 kN (37 lbf)

Static Load Rating C₀ 0.048 kN (11 lbf)

Fatigue Load Limit Pu 0.002 kN

Reference Speed 170,000 r/min

Limiting Speed 100,000 r/min

Minimum Load Factor kr 0.02

Ball Material Stainless Steel

Ring Material Stainless Steel

Cage Material Stainless Steel Stamped

Flange Type Integral Flange (R)

Seal Type Open (Unsealed)

Tolerance Class P0 (Normal/ABEC 1)

Radial Clearance CN (Normal)

Weight 0.0003 kg (0.3 g)

Temperature Range -30°C to 120°C

Typical Applications

The NMT D/W R144 R, with its flanged convenience, extreme miniaturization, ultra-high speed, and stainless steel corrosion resistance, covers an exceptionally wide range of high-end miniature applications:

 

Precision Instruments – measuring devices, optical scanners, chromatography products

 

Miniature Motors – high-speed micro-motors, stepper motors

 

Medical Devices – high-speed dental handpieces, surgical tools

 

Optical Equipment – laser scanners, rotating mirrors, optical encoders

 

Semiconductor Manufacturing Equipment – precision wafer processing, chip packaging

 

Office Automation Equipment – printers, scanners

 

Food Machinery – corrosion-resistant miniature transmission mechanisms

 

Aerospace Micro-Components – micro-actuators, sensors

 

Industrial Robots – micro high-speed rotary joints, 3D printers

 

Models and Toys – micro high-speed rotating components (e.g., yo-yos)

 

Instrumentation and Control Devices – precision sensing and control systems

 

Important Installation Notes

✅ This bearing features an integral flange on the outer ring (R) – installation allows direct axial location through the flange, eliminating the need for additional retaining rings or circlips, significantly simplifying installation and saving axial space.

 

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

 

✅ Ensure shaft and housing fits comply with P0 grade requirements. Shaft abutment diameter: da min. 3.8 mm; housing abutment diameter: Da max. 5.5 mm; maximum chamfer radius: ra max. 0.1 mm.

 

✅ Due to the extremely small size (only 0.3 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 ultra-high-speed performance.

 

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

 

⚠️ This bearing features an open design (unsealed) – select appropriate lubrication method based on application: grease lubrication for general high-speed applications, oil-mist or oil-air lubrication for extreme high-speed machining.

 

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 D/W R144 R bearing is manufactured to strict Japanese quality standards – from ring material (high-purity stainless steel) and rolling elements to superfinishing processes. The combination of flanged design (R), stainless steel material (W series), inch ultra-miniature series, stainless steel stamped cage, 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 flanged convenience, extreme miniaturization, ultra-high speed, and corrosion resistance.

 

Choose NMT D/W R144 R for:

 

✅ Flanged design – easy installation, space saving

 

✅ Extreme miniaturization – 3.175×6.35×2.38 mm, only 0.3 g

 

✅ 100,000 r/min ultra-high-speed performance – industry-leading

 

✅ Stainless steel material – corrosion resistance, extended life

 

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

 

✅ Stainless steel stamped cage – low friction, high speed

 

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

 

✅ Ultra-lightweight – only 0.3 g

 

✅ Japanese precision manufacturing quality