1 Complete Model, Dimensions, Loads & Technical Parameters

Full Model: 7004 ACD/HCP4ADGA

Model Code Explanation

7004: Base specification of 70 series precision angular contact bearing; ACD: 25° contact angle, D-type high-load two-point contact raceway geometry; HCP4A: composite material, P4A ultra-precision tolerance grade; DGA: Universal Duplex General Assembly, factory calibrated duplex set, supporting flexible conversion of three layouts. Two bearings are precisely selected at factory and shall not be mixed with other single bearings.

Standard Dimension Parameters

Bore d: 20 mm

Outer diameter D: 42 mm

Width B: 24 mm

Contact angle: 25 °

Load Performance Data

Basic dynamic load rating Cr: 13.5 kN

Basic static load rating C0r: 8.15 kN

Speed note: Contact SKF to obtain technical data of achievable operating speed

Full Product Attributes

Contact style: standard two-point contact

Row: 2 rows (duplex matched unit)

Race structure: integrated inner ring, integrated outer ring

Internal design: D-type high-load optimized design

Interchangeable matched configuration: available, back-to-back (<>), face-to-face (><), tandem (>>)

Matching arrangement: universal matching

Quantity of bearings in set: 2 units

Preload / clearance specification: ultra-light preload

Tolerance class: P4A precision grade

Material: composite material

Coating: uncoated

Seal: open type without seals

Pre-filled lubricant: none, lubrication configured on demand

Indicative carbon footprint for new product: 0.44 kg CO₂e

Net weight: 0.118 kg

eClass code: 23-05-08-03

UNSPSC code: 31171531

Speed note: Actual operating speed is affected by lubrication, heat dissipation, continuous load and assembly coaxiality. Confirm reference limiting speed with SKF before formal selection.

2 Structure & Operating Characteristics

Japan NMT 7004 ACD/HCP4ADGA is a 25° D-type high-load universal duplex precision angular contact bearing, calibrated on end faces at factory and capable of three assembly layouts without extra grinding. The 25° large contact angle delivers outstanding axial stiffness, ideal for applications dominated by axial load. Optimized D-type high-load raceway enlarges rolling contact area, reduces contact stress and improves load capacity and fatigue life. Integrated inner and outer rings maintain high rigidity, minimize assembly deformation and sustain long-term high-precision rotation.

Back-to-back (<>): wide support span, superior anti-overturning performance for heavy-duty spindles under bidirectional axial force and bending moment;

Face-to-face (><): higher tolerance for assembly coaxial error, suitable for compact axial space and moderate overturning load;

Tandem (>>): superimposed unidirectional axial load capacity for sustained single-direction axial thrust.

The bearing set adopts factory ultra-light preload, balancing axial rigidity and temperature rise at high speed to mitigate precision deviation caused by thermal elongation, applicable for medium-sized equipment running at high speed under light to medium loads. Open seal-free structure eliminates sealing friction to maximize speed potential. No pre-filled lubricant inside; high-speed grease or oil-air lubrication can be adopted according to working conditions.

The matched set must not be split and mixed with other single bearings. Destroyed matching accuracy leads to increased vibration, noise and shortened service life.

3 Core Performance Advantages

1. Factory Universal Pre-Matched Duplex Set: One set compatible with three assembly layouts, adapting to various load conditions and reducing spare part varieties.

2. 25° Contact Angle & D-Type High-Load Raceway: Strong axial stiffness, high load rating, balancing load capacity and continuous operation stability.

3. Standard Ultra-Light Factory Preload: Low heat generation during high-speed operation, suppress thermal deformation, suitable for long-term continuous high-speed operation under light & medium loads.

4. Composite Bearing Material: Lighter weight reduces rotational inertia, with prominent lightweight feature and low carbon footprint.

5. P4A Ultra-Precision Grade: Strict control over radial and axial runout to maintain stable long-term high-precision rotation.

6. Integrated Ring Structure: Sufficient structural rigidity to resist assembly deformation for medium-sized precision spindles in long-term continuous service.

7. Open Seal-Free Construction: Free of extra friction loss to achieve excellent limiting speed, compatible with advanced lubrication such as oil-air lubrication.

4 Typical Application Scenarios

4.1 Medium-Sized High-Speed Precision Heavy-Duty Spindles: Spindles for small & medium machining centers, high-speed precision grinding spindles, milling & engraving spindles with heavy axial load.

4.2 Multi-Condition Heavy-Duty Automated Rotary Mechanisms: Heavy-duty precision indexing turntables, medium lightweight robot joints, multi-purpose high-speed winding shafts.

4.3 Lightweight Precision Forming & Inspection Equipment: Rotary units of auxiliary precision injection molding machines, high-speed material testing equipment, precision tooling rotary platforms.

4.4 Medium & Small General Precision Machinery: High-speed textile spindles, rotary support assemblies of medium precision fluid equipment.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

P4A high-precision universal duplex matched bearings must be installed in dust-free clean environment. Remove burrs, dust and metal debris on shaft journals, housing bores and spacer mating surfaces. Thermal mounting is preferred. Direct impact on raceways, rolling elements and working surfaces is prohibited. Use the complete matched set; avoid mixing split bearings with other batches. Control interference fit properly: excessive interference leads to sharp temperature rise; insufficient interference causes outer ring creep and destroys preload status.

5.2 Matching Structure & Preload Instructions

This universal duplex bearing can be arranged as back-to-back (<>), face-to-face (><) or tandem (>>) according to load characteristics. Calculate axial force and overturning moment of shaft system before assembly to select optimal layout. Ultra-light preload is preset at factory. Align original matched end faces during assembly; do not arbitrarily add spacers to adjust preload. Contact manufacturer for customization if different preload level is required.

5.3 Lubrication Matching Solutions

No pre-filled lubricant inside bearing. High-speed low-viscosity grease is applicable for intermittent low-speed operation; oil-air circulating lubrication system is recommended for long-term continuous high-speed operation. Mixing different grades of lubricants is forbidden. Thoroughly clean bearing assembly before lubricant replacement.

5.4 Speed Parameter Note

Obtain reference limiting speed data directly from SKF. Reserve sufficient safety margin for continuous operation. Reduce operating speed under heavy load or poor heat dissipation to prevent premature fatigue failure.

6 Daily Maintenance & Fault Troubleshooting

Carry out low-speed no-load trial run after assembly, increase speed gradually, monitor vibration, noise and temperature rise. Formal operation can start only under stable working condition. Open design lacks built-in dust and coolant protection. External sealing must be installed at shaft end when dust, cutting fluid or moisture exists.

Replenish and replace lubricants periodically according to service cycle to maintain complete oil film on raceways. If continuous abnormal noise, precision decline or overheating occurs, sequentially inspect assembly interference, bearing layout, mounting direction, foreign particle intrusion and lubrication failure. Avoid severe impact loads which cause permanent ring deformation.