Product Overview

The NMT 7006 CD/HCP4ADBC is a pre-assembled duplex back-to-back matched ultra-precision hybrid ceramic angular contact ball bearing set, comprising 2 rows of bearings precision-paired in a back-to-back (<>) configuration. With a total width of 26 mm (13 mm per row × 2), a 30 mm bore, and a 55 mm outer diameter, this set features a 15° contact angle (CD type) , D-type high-capacity design, silicon nitride (Si₃N₄) hybrid ceramic rolling elements, and factory-preset medium preload (Class C) , delivering exceptional system rigidity and bidirectional axial load capacity for high-speed spindles.

 

The bearing set offers a basic dynamic load rating of 23.4 kN and static load rating of 16.0 kN – nearly double the capacity of a single 7006 CD/HCP4A bearing (14.3 kN / 8.0 kN). The back-to-back configuration provides maximum overturning moment rigidity and bidirectional axial load capability, while the P4A super-precision tolerance class ensures micron-level rotational accuracy at high speeds.

 

Model Code Decoding – Understanding NMT 7006 CD/HCP4ADBC

Code Meaning

7006 Basic series designation, 30 mm bore, compact design

CD 15° contact angle design – higher limiting speed, lower heat generation for ultra-high-speed operation

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

P4A Super-precision tolerance class – dimensional accuracy P4, running accuracy exceeding P4

DB Duplex Back-to-Back – contact angle directions face outward (<>), providing maximum overturning rigidity

C Medium preload (Class C) – optimal balance between high-speed capability and system rigidity

Core Feature: The back-to-back (<> ) configuration extends the load action points outward, creating a larger effective span (bearing center distance) that significantly enhances spindle resistance to bending moments. Combined with Class C medium preload, this bearing set maintains sufficient contact stiffness at high speeds while avoiding excessive temperature rise from over-preloading.

 

Core Performance Advantages

1. Back-to-Back Configuration – Maximum System Rigidity and Bidirectional Load Capacity

The back-to-back (<> ) arrangement orients the contact angles outward in opposite directions, maximizing the effective span and providing the highest overturning moment rigidity. Whether facing axial load direction changes, radial cutting force fluctuations, or bending moment impacts, this configuration delivers the most stable rotational support. With 23.4 kN dynamic and 16.0 kN static ratings, load capacity nearly doubles compared to single-row bearings.

 

2. 15° Contact Angle – Superior High-Speed Performance

The 15° small contact angle generates less frictional heat at equivalent speeds. Combined with hybrid ceramic rolling elements, the bearing set maintains extremely low temperature rise during high-speed operation – ideal for 56,000 r/min-class ultra-high-speed electric spindle applications.

 

3. Hybrid Ceramic Technology – Speed and Durability Combined

Silicon nitride ceramic balls feature lower density, lower thermal expansion, and higher elastic modulus – significantly reducing centrifugal forces and frictional heat at high speeds while improving seizure resistance and extending maintenance intervals. The lightweight nature of ceramic balls further amplifies high-speed stability advantages in back-to-back configurations.

 

4. Medium Preload (Class C) – The Golden Balance of Rigidity and Temperature

Class C medium preload provides "just-right" internal contact stiffness. Compared to light preload (A/L1), Class C offers higher system rigidity; compared to heavy preload (D/E), Class C maintains lower operating temperatures. This balance makes it the most versatile pairing choice, adaptable to the vast majority of high-speed precision spindle applications.

 

5. Factory Precision Matching – Uniform Load Distribution

This is a non-universal matchable fixed set. Both bearings undergo end-face matching grinding and preload setting at the NMT factory, ensuring highly uniform load distribution between the two rows, preventing individual bearing overload, and significantly extending overall set service life.

 

6. Lightweight and Sustainable

The set weighs only 0.185 kg (total for both rows) with a carbon footprint of just 0.69 kg CO₂e – delivering exceptional rigidity while maintaining lightweight and sustainable design.

 

Typical Applications

The NMT 7006 CD/HCP4ADBC is ideally suited for precision equipment demanding high system rigidity, bidirectional axial load capacity, and ultra-high-speed operation:

 

High-Speed Machining Center Spindles – vertical/horizontal milling and boring spindles

 

CNC Turning Centers – high-speed turning spindles (bidirectional cutting forces)

 

PCB Drilling/Routing Machines – high-frequency start-stop, high-speed drilling spindles

 

Precision Mold Engraving/Milling Machines – high-surface-quality machining

 

Grinding Machine Wheel Spindles – precision internal/external grinding

 

High-Speed Electric Spindles – various high-speed rotary machining units

 

Robot Joints/High-Precision Rotary Actuators – bidirectional axial positioning applications

 

Important Installation Notes

⚠️ This is a non-universal matched fixed set (DB) . The 2 bearings are supplied as one complete unit. Do not interchange or mix with other bearings of the same model.

 

⚠️ The back-to-back configuration (<> ) is directional. Ensure the contact angles face outward to achieve the expected overturning rigidity.

 

⚠️ This set comes with factory-preset medium preload (Class C) . No additional preload adjustment is required during installation, but ensure shaft and housing fits comply with NMT recommended tolerances.

 

⚠️ Maximum limiting speed depends on lubrication, mounting fit, and heat dissipation conditions. Oil-air lubrication is strongly recommended to fully realize the high-speed potential. Please consult NMT technical engineers for specific speed data.

 

NMT Quality Commitment

Japan NMT (Enmutī) applies stringent end-face matching grinding and preload control to every DB back-to-back bearing set, ensuring load-sharing deviation between the two rows is minimized to an extremely small range. The 7006 CD/HCP4ADBC delivers P4A accuracy, D-type high-capacity design, 15° contact angle high-speed performance, and Class C medium-preload rigidity for long-lasting, stable rotational support in your bidirectional high-speed spindles.

 

Choose NMT 7006 CD/HCP4ADBC for:

 

✅ Back-to-back configuration – maximum overturning rigidity

 

✅ 15° contact angle ultra-high-speed performance

 

✅ Hybrid ceramic technology – speed and durability together

 

✅ Class C medium preload – optimal rigidity-temperature balance

 

✅ P4A super-precision running accuracy

 

✅ Factory pre-matched – ready to install

 

✅ Bidirectional axial load capacity

 

✅ Ultra-lightweight green design