1 Complete Model, Dimensions, Loads & Technical Parameters

Full Model: 7006 ACD/P4AQGC

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;

QGC: 4-bearing universal matched set, factory medium 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: support back-to-back (<>), face-to-face (><), tandem (>>) layout

Matching configuration: universal match

Quantity in set: 4 bearings

Preload / clearance: medium 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: Medium preload balances rigidity and temperature rise. Actual permissible speed depends on lubrication, heat dissipation, load and coaxiality. Reserve sufficient safety margin during selection.

2 Structure & Operating Characteristics

Japan NMT 7006 ACD/P4AQGC is a 25° D-type high-load 4-piece universal matched precision angular contact ball bearing with integrated bearing steel rings. D-type raceway expands effective contact area and improves load capacity; 25° contact angle delivers excellent axial load and anti-tilting performance.

QGC stands for factory dimension-sorted universal matched set of four bearings. There is no fixed assembly sequence. Users can flexibly configure DB back-to-back, DF face-to-face, DT tandem four-stack layout according to equipment load requirements. Medium preload is preset at factory. Open design supports high-speed grease and oil-air lubrication, no pre-filled grease inside bearings.

Medium preload achieves balanced axial rigidity and operating temperature. It allows higher continuous speed than heavy preload versions and provides better heavy-load stiffness than ultra-light preload. Bearings from different sets cannot be split and mixed, which will damage matching accuracy.

3 Core Performance Advantages

1. D-Type High-Load Raceway + 25° Contact Angle: Excellent combined load capacity and sufficient axial rigidity for alternating bidirectional axial loads.

2. 4-Bearing Universal Matched Kit: Free assembly sequence, flexible four-stack layout selection to adapt different spindle force conditions.

3. Factory-Set Medium Preload: Balanced rigidity and temperature rise, compatible with continuous high-speed operation and heavy cutting conditions with wide versatility.

4. P4A Ultra-Precision Grade: Strict control over radial and axial runout for long-term precision operation.

5. Integrated Bearing Steel Rings: Good wear resistance, stable structure and reliable fatigue life.

6. Open Seal-Free Structure: Eliminates seal friction loss, compatible with oil-air lubrication and improves heat dissipation.

7. Modular Four-Bearing Assembly: Higher rated load and support stiffness than duplex bearings, suitable for heavy-duty medium-high speed machine tools.

4 Typical Application Scenarios

4.1 Precision Spindles for Medium & Heavy-Duty Machining Centers: Gantry machining centers, vertical machining centers, mold high-speed engraving & milling spindles.

4.2 Heavy-Duty Lead Screw Support Units for Large Machine Tools: Fixed-end supports for feed-axis ball screws on lathes, grinders and boring machines.

4.3 Heavy-Duty Precision Rotary Automation Components: CNC rotary tables, main rotary joints of heavy-duty robots.

4.4 General Precision Grinding Equipment: Wheel motor spindles for form grinders and cylindrical grinders under medium load.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

P4A high-precision 4-bearing universal matched set should be assembled in dust-free clean environment. Remove all burrs, metal chips and dust from shaft journals, housings and spacers. Controlled thermal mounting is recommended; direct impact on bearing faces and raceways is prohibited. Only bearings from the identical set can be combined; cross-set mixing is forbidden. Properly control interference fit; excessive interference changes factory preset preload and increases temperature rise.

5.2 Matching Layout & Preload Instructions

This universal matched set supports various four-stack layouts freely. Medium preload is preset at factory, spacer grinding is generally unnecessary under standard working conditions. Different stacking modes vary in rigidity and tilting resistance; select layout based on spindle cutting force. Contact manufacturer for customized preload grades if needed.

5.3 Lubrication Matching Solutions

No pre-filled lubricant inside bearings. Oil-air lubrication is preferred for long-term continuous medium-high speed operation to enhance heat dissipation. High-grade high-speed grease can be adopted for intermittent operation. Do not mix different lubricant types. Maintain lubrication pipelines regularly to prevent ingress of cutting fluid and dust.

5.4 Speed Parameter Note

Request reference limiting speed data from SKF. Reserve 10%～20% continuous speed safety margin for medium-preload four-bearing sets; reduce operating speed when axial load rises continuously.

6 Daily Maintenance & Fault Troubleshooting

Carry out gradual low-speed running-in after assembly, continuously monitor vibration, noise and temperature. Load cutting is permitted only under stable operating parameters. Open structure lacks protection against dust and cutting fluid; multi-stage external sealing must be installed on shaft end for harsh working conditions.

Ensure stable lubricant supply to maintain continuous oil film on raceways. In case of excessive temperature rise, increasing vibration or periodic noise, sequentially check interference fit, bearing installation orientation, coaxial accuracy, lubrication supply and contamination ingress. Avoid transient shock loads to prevent raceway indentation caused by unbalanced preload.