Product Overview

The NMT KDN.K02508AR0 is a thin section angular contact ball bearing belonging to the Reali-Slim® thin section bearing series. With a 25 mm bore, 41 mm outer diameter, and 8 mm width, this bearing features an ultra-thin constant section design – the bearing cross-section remains constant as the bore diameter increases, delivering significant space and weight savings while maintaining load capacity. As a single-row open design bearing with a 30° contact angle, it accommodates radial loads and unidirectional axial loads simultaneously, making it an ideal precision bearing solution for compact high-precision equipment in the NMT thin section bearing series.

 

Model Code Decoding – Understanding NMT KDN.K02508AR0

Code Meaning

KDN Kaydon thin section bearing series designation – Reali-Slim® thin section angular contact ball bearing

K Material & design code – AISI 52100 chrome steel rings and balls, open design (no seals)

025 Bore size – 25 mm (three-digit code, 025 = 25 mm)

08 Width/series code – 8 mm series thin section bearing

A Bearing type – Angular contact ball bearing (not ground for universal matching)

R Cage type – One-piece, circular pocket, stamped brass cage

0 Tolerance class – Kaydon Class 1 (equivalent to ABEC-1F)

Core Value: The KDN.K02508AR0 thin section bearing is an angular contact ball bearing optimized for unidirectional axial loads in the Reali-Slim® series. The 30° contact angle enables efficient accommodation of both radial loads and unidirectional axial loads simultaneously. The ultra-thin constant section design ensures the bearing cross-section remains constant as the bore diameter increases, delivering stable load capacity with only 8 mm width at a 25 mm bore. The open design facilitates flexible lubrication and maintenance. Chrome steel rings and balls with a brass cage provide excellent wear resistance and running accuracy. The ABEC-1 precision class ensures smooth motion in precision applications. The synergy of thin section design, 30° contact angle, and precision manufacturing makes this bearing the ideal bearing solution for space-constrained high-precision equipment requiring unidirectional axial load capacity.

 

Core Performance Advantages

1. 30° Contact Angle – Optimised Unidirectional Axial Load Capacity

This is an angular contact ball bearing with a 30° contact angle. This design enables it to accommodate radial loads and unidirectional axial loads simultaneously. The 30° contact angle provides an optimised balance between radial and axial load capacity, making it particularly suitable for applications where the axial load direction is fixed.

 

2. Ultra-Thin Constant Section Design – Compact Space, Lightweight

This bearing features a single cross-section design that remains constant as the bore diameter increases, delivering significant space and weight savings. With only 8 mm width at a 25 mm bore, it weighs just 0.0408 – 0.06 kg. The thin section design is ideal for compact designs with limited space, while weight reduction is critical for weight-sensitive applications such as aerospace.

 

3. High Precision Manufacturing – ABEC-1 Precision Class

This bearing is manufactured to high precision standards with a tolerance class of ABEC-1 (equivalent to Kaydon Class 1). Bore and OD tolerances are -0.01mm to 0. This is critical for applications requiring precise and smooth motion, making it suitable for robotics, automation equipment, medical imaging devices, and other applications with strict accuracy requirements.

 

4. High Load Capacity – Thin Section, Not Thin Capacity

Despite its thin cross-section, this bearing can accommodate significant radial, axial, and moment loads. With a dynamic radial load rating of 3.42 kN (767 lbf)  and a static radial load rating of 2.97 kN (668 lbf) , it delivers robust performance. Axial static load capacity reaches 10.5 kN (2,361 lbf) .

 

5. Brass Cage – Low Friction, Quiet Operation

The brass cage ensures quiet running performance. Brass offers excellent wear resistance and dimensional stability, maintaining precise rolling element guidance at high speeds while reducing friction and heat generation.

 

6. Low Friction and High Running Accuracy – Efficiency and Performance Combined

The thin section design and precision manufacturing process deliver low friction characteristics and high running accuracy. The low friction coefficient improves overall application efficiency, while high stiffness ensures stable operation under load.

 

7. Wide Operating Temperature Range

This bearing operates within a temperature range of -30°C to 110°C, capable of adapting to various demanding environments from cold to high-temperature processing.

 

8. Environmentally Compliant

This bearing is compliant with RoHS environmental standards with a carbon footprint of 0.15 kg CO₂e.

 

9. Clear Performance Specifications

 

Parameter Value

Bore d 25 mm

Bore Tolerance -0.01mm to 0

Outer Diameter D 41 mm

OD Tolerance -0.01mm to 0

Width B 8 mm

Width Tolerance +0.000 –0.127mm

Contact Angle 30°

Inner Ring Shoulder Diameter d₁ ≈ 30.94 mm

Outer Ring Shoulder Diameter D₁ ≈ 35.06 mm

Ball Diameter 3.969 mm

Dynamic Radial Load 3.42 kN (767 lbf)

Static Radial Load 2.97 kN (668 lbf)

Axial Static Load 10.5 kN (2,361 lbf)

Limiting Speed 21,340 r/min

Ring Material Chrome Steel (AISI 52100)

Ball Material Chrome Steel (AISI 52100)

Cage Material Brass

Seal Type Open

Tolerance Class ABEC-1

Weight 0.0408 – 0.06 kg

Carbon Footprint 0.15 kg CO₂e

Temperature Range -30°C to 110°C

Typical Applications

The NMT KDN.K02508AR0, with its 30° contact angle, ultra-thin constant section design, lightweight construction, and high precision characteristics, covers an exceptionally wide range of high-end compact applications:

 

Industrial Machinery – equipment requiring space savings without compromising load capacity

 

Robotics – precision robotic arms, automation machinery

 

Aerospace – instrumentation panels, weight-sensitive aviation components

 

Medical Equipment – advanced imaging devices, precision medical instruments

 

Automotive Applications – steering systems, electric motors

 

Semiconductor Manufacturing Equipment – precision wafer processing, chip packaging

 

Optical Equipment – laser scanners, rotating mirrors, optical encoders

 

Consumer Electronics – printers, small appliances

 

Important Installation Notes

✅ This bearing is an angular contact ball bearing with a 30° contact angle, accommodating radial loads and unidirectional axial loads simultaneously. Ensure the axial load direction matches the bearing design direction during installation.

 

✅ This bearing features an open design – select appropriate lubrication method based on application for flexible lubrication and maintenance.

 

✅ This bearing features an ultra-thin constant section design – ensure shaft and housing fits comply with precision requirements (bore tolerance -0.01mm to 0, OD tolerance -0.01mm to 0).

 

⚠️ This bearing features a thin section design – use specialized installation tools and avoid excessive force that could cause bearing deformation.

 

⚠️ This bearing is not universally matchable (not ground for universal matching) – if paired configurations or specific preload are required, order dedicated matched sets based on application requirements.

 

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

 

NMT Quality Commitment

Japan NMT (Enmutī) has deep expertise in the precision bearing industry, with breakthroughs in material purification, process refinement, scenario customisation, and intelligent upgrading, transforming precision bearings into core solutions addressing pain points across multiple industries. The NMT KDN.K02508AR0 bearing is manufactured to strict Japanese quality standards – from ring material (high-purity AISI 52100 chrome steel) and rolling elements to superfinishing processes. The combination of 30° contact angle, ultra-thin constant section design, chrome steel rings and balls, brass cage, ABEC-1 precision class, and open design makes this bearing the flagship precision bearing in the NMT thin section bearing series – offering the perfect balance of unidirectional axial load capacity, compact design, lightweight construction, and high precision performance.

 

Choose NMT KDN.K02508AR0 for:

 

✅ 30° contact angle – optimised radial and unidirectional axial combined load capacity

 

✅ Ultra-thin constant section design – compact space, lightweight

 

✅ Chrome steel material – high hardness, wear resistance, extended life

 

✅ 3.42 kN (767 lbf) radial load capacity – thin section, not thin capacity

 

✅ Brass cage – low friction, quiet operation

 

✅ ABEC-1 high precision class – precise smooth motion

 

✅ 21,340 r/min high speed performance

 

✅ Wide temperature range – -30°C to 110°C

 

✅ RoHS compliant – carbon footprint 0.15 kg CO₂e

 

✅ Japanese precision manufacturing quality