Product Overview

The NMT S71901 CD/HCP4A is a sealed, single-row super-precision hybrid ceramic angular contact ball bearing. With a 12 mm bore, 24 mm outer diameter, and 6 mm width, this bearing is the ultra-compact member of the 719 series. Featuring a 15° contact angle (CD type) and D-type high-capacity design, combined with silicon nitride (Si₃N₄) hybrid ceramic rolling elements (HC) and a phenolic resin cage, and equipped with non-contact rubber seals on both sides, it integrates ultra-high-speed performance, high load capacity, maintenance-free sealing, and super-precision rotational accuracy into a single package, accommodating radial and unidirectional axial loads simultaneously.

 

The bearing offers a radial dynamic load rating of 2.65 kN (596 lbf) and a static load rating of 1.25 kN (281 lbf) . Manufactured to the P4A super-precision tolerance class (ABEC 7) with a 15° contact angle and hybrid ceramic technology, the bearing achieves a limiting speed of 85,000 r/min under grease lubrication and 100,000 r/min under oil lubrication. The bearing weighs only 0.01 kg (10 g)  with an operating temperature range of -30°C to 110°C.

 

Model Code Decoding – Understanding NMT S71901 CD/HCP4A

Code Meaning

S Sealed design – equipped with non-contact rubber seals on both sides

71901 Basic series designation, 12 mm bore, 24 mm OD, 6 mm width

CD 15° contact angle design – generates less frictional heat than 25° designs, offering higher limiting speed potential

HC Hybrid ceramic – rolling elements made of bearing-grade silicon nitride (Si₃N₄) 

P4A Super-precision tolerance class – ABEC 7 / ISO P4 class

Core Value: The S sealed design effectively prevents contaminant ingress, extending bearing service life. The CD-type 15° contact angle is optimized for high-speed operation, offering higher limiting speed potential than 25° designs. The D-type high-capacity design, with optimized rolling element parameters – ball diameter 3.175 mm, 13 ceramic balls per bearing – achieves outstanding load capacity. HC hybrid ceramic technology drastically reduces centrifugal forces and frictional heat at high speeds. P4A super-precision ensures bore and OD tolerances are controlled within -0.004 mm to 0 – these five elements work together to make this bearing the ultimate precision bearing solution for miniature ultra-high-speed spindles.

 

Core Performance Advantages

1. Non-Contact Seals – Maintenance-Free, Extended Life

The bearing features non-contact rubber seals on both sides that effectively prevent contaminants such as cutting fluids and dust from entering the bearing interior, while the non-contact design avoids friction between the seal lip and the inner ring – adding no extra resistance or heat generation. Integral sealing prolongs bearing service life. This ensures stable temperature performance even at 100,000 r/min ultra-high speeds, while significantly extending maintenance intervals.

 

2. 15° Contact Angle – The Ideal Choice for Ultra-High-Speed Operation

The 15° contact angle is specifically optimized for ultra-high-speed operation in angular contact ball bearings. Compared to 25° designs, the 15° contact angle generates less frictional heat, offering higher limiting speed potential. Combined with P4A super-precision and hybrid ceramic technology, the bearing achieves an oil lubrication limiting speed of 100,000 r/min.

 

3. D-Type High-Capacity Design – High Load in Compact Space

The D-type high-capacity design optimizes ball complement and internal geometry – ball diameter 3.175 mm, 13 ceramic balls per bearing – achieving an outstanding 2.65 kN (596 lbf) dynamic and 1.25 kN (281 lbf) static load rating. Within an extremely compact 6 mm width, it provides load capacity far exceeding bearings of the same size class.

 

4. Hybrid Ceramic Technology – The Foundation of Ultra-High-Speed Performance

Silicon nitride (Si₃N₄) ceramic balls have only 60% the density of bearing steel, drastically reducing centrifugal forces and frictional heat at high speeds. Ceramic materials also offer lower thermal expansion coefficients and higher elastic modulus, effectively suppressing geometric deformation at high speeds. Combined with chrome steel rings and a phenolic resin cage, this achieves the perfect balance of high rigidity, ultra-high speed, and durability.

 

5. P4A Super-Precision Grade – Micron-Level Accuracy

The P4A tolerance class (ABEC 7) guarantees minimal radial runout and vibration. Bore tolerance -0.004 mm to 0, outside diameter tolerance -0.005 mm to 0, meeting stringent surface quality and dimensional consistency requirements. Ball count 13. Operating temperature range is -30°C to 110°C.

 

6. Extreme Lightweight – Only 10 Grams

The bearing weighs only 0.01 kg (10 g) . The extremely low rotating mass effectively reduces centrifugal loads and inertia moments at high speeds.

 

7. Lightweight Phenolic Resin Cage

The lightweight high-strength phenolic resin cage provides excellent guidance accuracy and low friction at high speeds. This material offers an excellent strength-to-weight ratio, contributing to reduced centrifugal forces, friction, and heat generation – a key factor in achieving the 100,000 r/min oil lubrication limiting speed.

 

8. Factory Pre-Lubricated – Ready to Install

This bearing comes pre-lubricated from the factory with grease – ready to install out of the box without additional lubrication handling, significantly simplifying the assembly process.

 

9. Clear Performance Specifications

 

Parameter Value

Bore d 12 mm

Bore Tolerance -0.004 mm to 0

Outer Diameter D 24 mm

OD Tolerance -0.005 mm to 0

Width B 6 mm

Contact Angle 15°

Dynamic Radial Load 2.65 kN (596 lbf)

Static Radial Load 1.25 kN (281 lbf)

Ball Diameter Dw 3.175 mm

Ceramic Balls per Bearing 13

Speed (Grease) 85,000 r/min

Speed (Oil) 100,000 r/min

Distance to Pressure Point a 5.4 mm

Ball Material Silicon Nitride (Si₃N₄)

Ring Material Chrome Steel

Cage Material Phenolic Resin

Seal Type Non-Contact Rubber Seals (both sides)

Tolerance Class P4A (ABEC 7)

Weight 0.01 kg (10 g)

Temperature Range -30°C to 110°C

Typical Applications

The NMT S71901 CD/HCP4A, with its sealed protection, 15° contact angle ultra-high-speed performance, and hybrid ceramic technology, covers an exceptionally wide range of high-end miniature applications:

 

Machine Tool Spindles – CNC machine tools, precision grinders

 

High-Speed Machinery – PCB drilling machines, engraving machines

 

Aerospace Components – gyroscopes, actuators, jet engine parts

 

Medical Equipment – high-speed dental handpieces, surgical tools, medical imaging devices

 

Semiconductor Manufacturing – precision wafer processing spindles

 

High-Frequency Motors – high-speed, high-precision miniature motors

 

Industrial Robots – micro high-speed rotary joints

 

Precision Instruments – measuring devices, optical scanners

 

Gas Turbines and Centrifugal Separators – high-speed rotating machinery

 

Food Machinery, Indexing Heads, Coating Equipment and other industrial precision equipment

 

Important Installation Notes

✅ This bearing features non-contact seals and comes pre-lubricated from the factory with grease – ready to install out of the box.

 

✅ To achieve the 100,000 r/min oil lubrication limiting speed, oil-air or oil-mist lubrication is recommended; grease lubrication limits speed to 85,000 r/min.

 

✅ This is a non-universal matchable single bearing (no G/GA suffix). For paired configurations (DB, DF, DT arrangements), please order the corresponding pre-matched set.

 

⚠️ Ensure shaft and housing fits comply with P4A grade requirements (bore tolerance -0.004 mm to 0, OD tolerance -0.005 mm to 0) to achieve the expected rotational accuracy and service life.

 

⚠️ A single-row angular contact ball bearing can accommodate axial load in one direction only. Radial loads generate an additional axial force that must be counteracted through paired mounting.

 

⚠️ This bearing has no preload setting – preload must be adjusted during paired installation based on the specific configuration.

 

⚠️ Hybrid ceramic bearings are more sensitive to installation shock. Heat mounting or hydraulic installation methods are recommended – avoid impact on raceways or rolling elements. Due to the extremely small size (only 10 g), extra care is required during installation to avoid excessive force.

 

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

 

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 S71901 CD/HCP4A bearing is manufactured to strict Japanese quality standards – from ring material (high-purity chrome steel), ceramic balls (HIP silicon nitride), to superfinishing processes. The combination of 15° contact angle (CD type), D-type high-capacity design, hybrid ceramic technology (HC), P4A super-precision, non-contact seals, and phenolic resin cage makes this bearing the flagship miniature precision bearing in the NMT 719 series – offering the perfect balance of ultra-high speed, maintenance-free operation, and ultra-precision performance.

 

Choose NMT S71901 CD/HCP4A for:

 

✅ Non-contact seals – maintenance-free, extended life

 

✅ 15° contact angle – 100,000 r/min ultra-high-speed performance

 

✅ D-type high-capacity design – 2.65 kN (596 lbf) high load capacity

 

✅ Hybrid ceramic technology – the foundation of ultra-high-speed performance

 

✅ P4A super-precision running accuracy – ABEC 7 class

 

✅ Extreme lightweight – only 10 g

 

✅ Phenolic resin cage – low friction, low noise, high speed

 

✅ Factory pre-lubricated – ready to install