1 Complete Model, Dimensions, Loads & Technical Parameters

Full Model: 7006 ACD/P4AQBCD

Model Code Explanation

7006: Basic dimension of 70 series precision angular contact ball bearing;

ACD: 25° contact angle, D-type high-load optimized raceway geometry;

P4A: P4A ultra-precision tolerance grade;

QBCD: 4-bearing set, fixed <<>> arrangement, factory heavy preload.

Standard Dimension Parameters

Bore d: 30 mm

Outer diameter D: 55 mm

Overall width B: 52 mm

Contact angle: 25 °

Performance Data

Basic dynamic load rating Cr: 36.4 kN

Basic static load rating C0r: 30.5 kN

Speed note: Contact SKF to obtain reference achievable rotational speed.

Full Product Attributes

Contact form: standard two-point contact

Number of bearings per set: 4

Ring structure: integrated inner ring and outer ring

Internal design: D-type high-load optimized design

Universal matching bearing: not supported, arrangement fixed

Matching configuration: fixed <<>> quadruple stack

Quantity in set: 4 bearings

Preload / clearance: heavy preload

Tolerance class: P4A precision grade

Material: bearing steel

Coating: uncoated

Seal: open type without seals

Pre-filled lubricant: none, lubrication scheme configured on site

Indicative carbon footprint for new product: 1.6 kg CO₂e

Net weight: 0.438 kg

eClass code: 23-05-08-04

UNSPSC code: 31171531

Speed note: Actual permissible speed is affected by lubrication, heat dissipation, continuous load, assembly coaxiality and preload. Heavy preload assembly has higher temperature sensitivity; sufficient safety margin must be reserved during selection.

2 Structure & Operating Characteristics

Japan NMT 7006 ACD/P4AQBCD is a 25° D-type high-load quadruple set precision angular contact ball bearing with integrated bearing steel rings. D-type raceway enlarges effective contact area and improves load capacity. The 25° contact angle provides excellent axial rigidity for heavy axial load applications.

QBCD means four bearings dimensionally sorted in factory with fixed <<>> quadruple arrangement. Do not rearrange bearings or switch to DB/DF/DT layout. Heavy preload is calibrated at the factory. Open non-sealed design supports high-speed grease and oil-air lubrication; no grease pre-filled inside bearings.

Heavy preload delivers ultra-high axial rigidity and strong tilting resistance, yet generates higher temperature rise compared with light preload variants. It targets medium-speed, heavy-cutting spindles and lead screw supports requiring high rigidity. Bearings from different sets cannot be split and mixed for assembly.

3 Core Performance Advantages

1. D-Type High-Load Raceway + 25° Contact Angle: Strong combined load capacity and outstanding axial rigidity to sustain continuous heavy bidirectional axial loads.

2. Factory-Sorted 4-Bearing Set with Fixed <<>> Layout: Consistent matching accuracy, fixed assembly sequence ensuring balanced rigidity across the stack.

3. Factory-Set Heavy Preload: Extreme axial stiffness and superior anti-tilting performance to minimize spindle deflection under heavy cutting loads.

4. P4A Ultra-Precision Grade: Strict control over radial and axial runout to maintain precision under long-term heavy-duty operation.

5. Integrated Bearing Steel Rings: Wear-resistant, stable structure and reliable fatigue performance.

6. Open Seal-Free Structure: No seal friction loss, compatible with oil-air lubrication and favorable for heat dissipation.

7. Quadruple Stack Assembly: Much higher rated load and overall rigidity than duplex sets, meeting requirements of heavy-duty machine tools.

4 Typical Application Scenarios

4.1 Heavy-Duty CNC Precision Spindles: Gantry machining center spindles, heavy-duty CNC milling machines, high-power grinding motor spindles.

4.2 Heavy-Duty Precision Ball Screw Supports: Fixed-end support units for feed axes on large machine tools.

4.3 Heavy-Duty Automated Rotary Mechanisms: Large precision rotary tables, main rotary joints of heavy-load robots.

4.4 Precision Heavy-Duty Grinding Equipment: Wheel spindles for cylindrical grinders and form grinders.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

P4A high-precision quadruple bearing sets must be assembled in dust-free constant-temperature cleanrooms. Remove all burrs, dust and contaminants from shaft journals, housings and spacers. Controlled thermal mounting is recommended; direct impact on bearing faces and raceways is forbidden. Assemble the four bearings strictly following specified <<>> order, do not swap positions. Properly control interference fit; excessive interference increases temperature rise and impairs factory preload.

5.2 Matching Layout & Preload Instructions

This model is supplied as fixed <<>> quadruple stack, not universal match. Conversion to DB, DF or DT configuration is prohibited. Heavy preload is preset at factory; spacer modification is unnecessary under standard conditions. Contact manufacturer for customized preload grades if required. High rigidity comes with higher thermal sensitivity; not suitable for continuous ultra-high-speed operation.

5.3 Lubrication Matching Solutions

No pre-filled lubricant inside bearings. Oil-air lubrication is preferred for continuous medium-speed operation to improve heat dissipation. High-temperature high-speed grease can be used for intermittent medium-low speed operation. Do not mix different lubricant types. Maintain lubrication pipelines regularly to prevent ingress of metal chips and dust.

5.4 Speed Parameter Note

Request reference limiting speed data from SKF. Reduce continuous operating speed by 15%～25% for long-term service with heavy preload combinations; further lower speed under increased axial load.

6 Daily Maintenance & Fault Troubleshooting

Carry out gradual low-speed running-in after assembly, continuously monitor vibration, noise and temperature; load operation can start only under stable conditions. Open design provides no dust protection; multi-stage external shaft sealing must be implemented if cutting fluid or dust exists.

Keep steady lubricant supply to maintain continuous oil film on raceways. In case of rapid temperature rise, growing vibration or periodic noise, sequentially verify assembly sequence, interference fit, coaxial accuracy, lubrication supply and contamination ingress. Avoid transient shock loads which cause preload imbalance and indentation damage on raceways.