Product Overview

The NMT 7013 ACD/P4AQBCC is a pre-assembled quadruplex QBC matched super-precision all-steel angular contact ball bearing set, comprising 4 rows of bearings precision-paired in a tandem-back-to-back-tandem (<<>>) QBC configuration. With a total width of 72 mm (18 mm per row × 4), a 65 mm bore, and a 100 mm outer diameter, this set features a 25° contact angle (AC type) and D-type high-capacity design, combined with all-steel rolling elements and a phenolic resin cage, factory-preset with Class C moderate preload, delivering ultimate bidirectional axial rigidity, overturning moment resistance, and high load capacity.

 

The bearing set offers a radial dynamic load rating of 23,400 lbf (104 kN) and a static load rating of 31,500 lbf (140 kN) . The QBC (tandem-back-to-back-tandem) configuration provides the highest system rigidity and bidirectional axial load capacity. Manufactured to the P4A super-precision tolerance class with a 25° contact angle and Class C moderate preload, the set achieves a limiting speed of 31,000 r/min. The bore and outside diameters of the bearings are matched to within a maximum of one-third of the permitted diameter tolerance, ensuring highly uniform load distribution across all 4 rows. The set weighs 1.72 kg with an operating temperature range of -30°C to 110°C.

 

Model Code Decoding – Understanding NMT 7013 ACD/P4AQBCC

Code Meaning

7013 Basic series designation, 65 mm bore, 100 mm OD

AC Angular contact design with 25° contact angle

D D-type high-capacity design – best suited for heavier loads compared to equivalent B and E type high-speed bearings

P4A Super-precision tolerance class – bore and OD tolerances -0.004mm to 0

QBC Quadruplex QBC arrangement (Quadruplex Back-to-Back-Cascade) – 4 bearings arranged in tandem-back-to-back-tandem (<<>>) configuration

C Class C moderate preload – optimized internal contact stiffness for high-speed heavy-load applications

Core Configuration Insight: The QBC (<<>>) configuration consists of 4 bearing rows – the center two in back-to-back (<> ) providing maximum overturning rigidity, with one tandem (>>) row on each side doubling unidirectional axial load capacity. This represents the highest rigidity and highest load capacity configuration available in angular contact bearing arrangements. This is a non-universal matchable fixed set – the 4 bearings are factory end-face matched, with bore and OD matching precision controlled within one-third of the allowable tolerance, and must not be interchanged or mixed with other bearings.

 

Core Performance Advantages

1. QBC Quadruplex Configuration – Ultimate System Rigidity and Bidirectional Axial Load Capacity

The QBC (<<>>) configuration combines the dual advantages of back-to-back (<> ) and tandem (>>) arrangements:

 

Center two rows back-to-back: Provides maximum overturning moment rigidity, effectively resisting bending and eccentric loads

 

One tandem row on each side: Doubles unidirectional axial load capacity on each side, with symmetric layout achieving perfect bidirectional axial load balance

 

Radial dynamic load rating 23,400 lbf (104 kN) , static load rating 31,500 lbf (140 kN) – nearly quadruple single-row capacity

 

2. 25° Contact Angle (AC Type) + D-Type High-Capacity Design – High Load and High Rigidity Combined

The 25° contact angle delivers superior axial rigidity while maintaining ample radial capacity. The D-type high-capacity design, with optimized internal geometry and rolling element parameters (ball diameter 11.112 mm, 20 balls per bearing), is best suited for heavier loads compared to equivalent B and E type high-speed bearings, achieving an outstanding 104 kN dynamic and 140 kN static load rating within a compact 72 mm total width.

 

3. Class C Moderate Preload – Ideal for High-Speed Heavy-Load Applications

Class C moderate 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 31,000 r/min limiting speeds.

 

4. P4A Super-Precision Grade – Micron-Level Spindle Accuracy

The P4A tolerance class guarantees minimal radial runout and axial play. All 4 bearings undergo factory precision end-face matching grinding, with bore and OD matching precision controlled within one-third of the allowable tolerance, ensuring highly uniform load distribution across all rows, preventing individual bearing overload, and significantly extending overall set service life. Operating temperature range is -30°C to 110°C.

 

5. Lightweight Phenolic Resin Cage

The lightweight high-strength phenolic resin cage provides excellent guidance accuracy and low friction at high speeds, while its low mass further reduces centrifugal loads – a key factor in achieving the 31,000 r/min limiting speed.

 

6. 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.

 

7. Clear Performance Specifications

 

Parameter Value

Bore d 65 mm

Outer Diameter D 100 mm

Total Width B 72 mm (4×18 mm)

Contact Angle 25°

Dynamic Radial Load 23,400 lbf (104 kN)

Static Radial Load 31,500 lbf (140 kN)

Ball Diameter Dw 11.112 mm

Balls per Bearing 20

Limiting Speed 31,000 r/min

Ball Material Chrome Steel

Ring Material Chrome Steel

Cage Material Phenolic Resin

Seal Type Open

Tolerance Class P4A

Preload Class C (Moderate)

Arrangement QBC (<<>>)

Bearings in Set 4

Weight 1.72 kg

Temperature Range -30°C to 110°C

Typical Applications

The NMT 7013 ACD/P4AQBCC is engineered for premium precision equipment demanding ultimate system rigidity, high load capacity, and uncompromising accuracy:

 

Heavy-Duty Vertical/Horizontal Machining Center Spindles – powerful milling and heavy boring spindles

 

High-Rigidity 5-Axis Machining Centers – complex surface machining, aerospace structural component processing

 

Heavy-Duty CNC Turning Centers – large-depth, high-feed turning spindles

 

Precision Grinding Machine Wheel Spindles – high-accuracy internal/external grinding, jig grinders

 

Gear Cutting Machines – hobbing, shaping, milling, and grinding spindles

 

Large Mold Machining Centers – high-rigidity spindles for combined roughing and finishing

 

Aerospace Component Machining Equipment – high-speed heavy cutting of titanium and superalloys

 

Semiconductor Manufacturing Equipment – high-precision wafer processing spindles

 

Important Installation Notes

⚠️ This is a non-universal matchable fixed set (QBC) – the 4 bearings are supplied as one complete unit. Do not interchange or mix with other bearings of the same model.

 

⚠️ The QBC (<<>>) configuration is strictly directional. Installation must strictly follow NMT's assembly drawings to ensure correct contact angle orientation for each row. Incorrect orientation will completely eliminate load capacity.

 

✅ This set comes with factory-preset Class C moderate 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).

 

✅ Bore and OD matching precision is controlled within one-third of the allowable tolerance – ensure shaft and housing bore concentricity and straightness meet P4A grade requirements.

 

✅ To achieve the 31,000 r/min limiting speed, oil-air or oil-mist lubrication is recommended.

 

⚠️ Total width is 72 mm. Ensure sufficient axial installation space.

 

⚠️ This set is open design – select appropriate lubrication method based on application.

 

NMT Quality Commitment

Japan NMT (Enmutī) applies the most stringent end-face matching grinding and preload control to every QBC quadruplex bearing set. All 4 bearings undergo complete factory matching and full-parameter inspection, with bore and OD matching precision controlled within one-third of the allowable tolerance, ensuring load-sharing deviation between rows is minimized to an extremely small range. The 7013 ACD/P4AQBCC delivers P4A accuracy, 25° contact angle high rigidity, D-type high-capacity design, QBC quadruplex ultimate rigidity, and Class C moderate preload for unparalleled rotational support in your premier heavy-duty high-speed spindles.

 

Choose NMT 7013 ACD/P4AQBCC for:

 

✅ QBC quadruplex configuration – ultimate system rigidity and bidirectional load capacity

 

✅ 25° contact angle + D-type high capacity – 104 kN high load capacity

 

✅ Class C moderate preload – ideal for high-speed heavy-load applications

 

✅ P4A super-precision running accuracy – bore/OD tolerance -0.004mm to 0

 

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

 

✅ Factory pre-matched – matching precision within one-third of tolerance

 

✅ 31,000 r/min ultra-high-speed performance

 

✅ -30°C to 110°C wide temperature range capability