Product Overview

The NMT 7012 CD/P4ADBB is a pre-assembled duplex back-to-back matched super-precision all-steel angular contact ball bearing set, comprising 2 rows of bearings precision-paired in a back-to-back (<>) configuration. With a total width of 36 mm (18 mm per row × 2), a 60 mm bore, and a 95 mm outer diameter, this set features a 15° contact angle (CD type) and D-type high-capacity design, combined with all-steel rolling elements and a phenolic resin cage, factory-preset with Class B light preload. It delivers ultimate system rigidity, exceptional overturning moment resistance, and bidirectional axial load capacity, accommodating radial and bidirectional axial loads simultaneously.

 

The bearing set offers a basic dynamic load rating of 66.3 kN and a static load rating of 69.5 kN. The DB back-to-back configuration extends the load action points outward, creating a maximum effective span that provides the highest overturning moment rigidity and bidirectional axial load capacity. Manufactured to the P4A super-precision tolerance class with D-type high-capacity design and Class B light preload, the set achieves a limiting speed of 34,000 r/min. The operating temperature range is -30°C to 110°C.

 

Model Code Decoding – Understanding NMT 7012 CD/P4ADBB

Code Meaning

7012 Basic series designation, 60 mm bore, 95 mm OD

CD 15° contact angle design – offers higher limiting speed and lower heat generation than 25° designs

P4A Super-precision tolerance class – dimensional accuracy to ISO P4 class, running accuracy superior to P4

DB Duplex Back-to-Back – 2 bearings mounted with contact angles facing outward (<>), providing maximum overturning rigidity and bidirectional axial load capacity

B Class B light preload – optimized internal contact stiffness for high-speed precision applications

Core Value: The DB back-to-back configuration extends the load action points outward, maximizing the effective span and significantly enhancing spindle resistance to bending moments. The CD-type 15° contact angle generates less frictional heat at equivalent speeds, offering higher limiting speed potential than 25° contact angle designs. The D-type high-capacity design is best suited for heavier loads compared to equivalent B and E type high-speed bearings. P4A super-precision ensures bore and OD tolerances are controlled within -0.004mm to 0 – these four elements work together to make this bearing set the flagship precision bearing solution offering the perfect balance of ultimate overturning rigidity, high load capacity, and ultra-high-speed performance.

 

Core Performance Advantages

1. Back-to-Back (DB) Configuration – Ultimate Overturning 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. The precision-matched pair ensures uniform load distribution across both rows, significantly enhancing overall system rigidity.

 

2. 15° Contact Angle (CD Type) + D-Type High-Capacity Design – Ultra-High Speed and High Load Combined

The 15° small contact angle generates less frictional heat at equivalent speeds, offering higher limiting speed potential than 25° contact angle designs, with a limiting speed of 34,000 r/min. The D-type high-capacity design, with optimized internal geometry and rolling element parameters, is best suited for heavier loads compared to equivalent B and E type high-speed bearings. Combined with a phenolic resin cage, it achieves an outstanding 66.3 kN dynamic and 69.5 kN static load rating within a compact 36 mm total width. The set weighs only 0.791 – 0.81 kg.

 

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

The D-type high-capacity design optimizes rolling element parameters – ball diameter 11.112 mm, 19 balls per bearing – to deliver exceptional load capacity. It is best suited for heavier loads compared to equivalent B and E type high-speed bearings.

 

4. Class B Light Preload – Ideal for High-Speed Precision Applications

Class B light preload provides "just-right" internal contact stiffness for high-speed spindles – eliminating internal clearance, reducing vibration and noise at high speeds, while avoiding excessive temperature rise from over-preloading. This ensures stable temperature performance even at 34,000 r/min limiting speeds.

 

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

The P4A tolerance class guarantees minimal radial runout and axial play. Bore and outside diameter tolerances are -0.004mm to 0, meeting stringent surface quality and dimensional consistency requirements. Operating temperature range is -30°C to 110°C.

 

6. Lightweight Phenolic Resin Cage

The lightweight high-strength phenolic resin cage provides excellent guidance accuracy and low friction at high speeds, contributing to reduced centrifugal forces, friction, and heat generation – a key factor in achieving the 34,000 r/min limiting speed.

 

7. All-Steel Construction – High Rigidity, Impact Resistance, Cost-Effectiveness

Premium chrome steel rings and balls offer higher fracture toughness and impact resistance than hybrid ceramic versions – more reliable under interrupted cutting and accidental overload conditions. All-steel bearings also offer significant cost advantages for high-volume industrial applications.

 

8. Clear Performance Specifications

 

Parameter Value

Bore d 60 mm

Outer Diameter D 95 mm

Total Width B 36 mm (2×18 mm)

Contact Angle 15°

Dynamic Load Rating 66.3 kN

Static Load Rating 69.5 kN

Ball Diameter Dw 11.112 mm

Balls per Bearing 19

Limiting Speed 34,000 r/min

Ball Material Chrome Steel

Ring Material Chrome Steel

Cage Material Phenolic

Seal Type Open

Tolerance Class P4A

Preload Class B (Light)

Arrangement Back-to-Back (<> ) DB

Bearings in Set 2

Weight 0.791 – 0.81 kg

Temperature Range -30°C to 110°C

Typical Applications

The NMT 7012 CD/P4ADBB, with its DB back-to-back ultimate overturning rigidity, D-type high-capacity design, and P4A super-precision grade, covers an exceptionally wide range of high-end applications:

 

High-Speed Machine Tool Spindles – CNC machine tools, precision grinders, milling center spindles

 

High-Speed Electric Spindles – high-speed rotary units

 

Machining Center Spindles – vertical/horizontal spindle systems

 

Precision Rotary Tables – high-accuracy rotary positioning

 

Aerospace Components – gyroscopes, actuators, jet engine parts

 

Medical Equipment – high-speed dental drills and medical imaging devices

 

Semiconductor Manufacturing Equipment – precision wafer processing spindles

 

Industrial Robots – high-precision transmission mechanisms and rotary axes

 

Industrial Pumps and Compressors – high-speed rotating machinery

 

Important Installation Notes

⚠️ This is a non-universal matchable 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 Class B light preload. No additional preload adjustment is required during installation. However, ensure shaft and housing fits comply with P4A grade requirements (bore/OD tolerance -0.004mm to 0).

 

✅ This set is open design – select appropriate lubrication method based on application. To achieve the 34,000 r/min limiting speed, oil-air or oil-mist lubrication is recommended.

 

⚠️ Ensure shaft and housing bore concentricity and straightness meet P4A grade requirements to achieve the expected rotational accuracy and service life.

 

NMT Quality Commitment

Japan NMT (Enmutī) applies strict Japanese quality standards to every 7012 CD/P4ADBB bearing set – from ring material (high-purity chrome steel) and rolling elements to superfinishing processes. Every DB back-to-back set undergoes factory end-face matching grinding and Class B light preload setting, ensuring load-sharing deviation between the two rows is minimized to an extremely small range. The combination of 15° contact angle (CD type), D-type high-capacity design, DB back-to-back ultimate rigidity, P4A precision, and Class B light preload makes this bearing set the flagship precision bearing solution in the NMT 7012 series – offering the perfect balance of ultimate overturning rigidity, high load capacity, and ultra-high-speed performance.

 

Choose NMT 7012 CD/P4ADBB for:

 

✅ DB back-to-back configuration – ultimate overturning rigidity and bidirectional axial load capacity

 

✅ 15° contact angle + D-type high capacity – 34,000 r/min ultra-high speed and 66.3 kN high load combined

 

✅ Class B light preload – ideal for high-speed precision applications

 

✅ P4A super-precision running accuracy

 

✅ All-steel – high rigidity, impact resistance, cost-effectiveness

 

✅ Factory pre-matched – ready to install