1 Complete Model & Code Explanation

Model: 7015 ACD/P4ADGA

Code Definition

7015: Basic dimension of 70 series light-duty single-row angular contact ball bearing

ACD: 25° nominal contact angle, machined solid brass cage design

P4: ISO P4 super precision grade, meets high-precision rotation requirements of high-speed spindles

D: Duplex set, factory end-face ground matched duplex bearing set with exclusive matching marks

G: Continuous oil-air circulation grooves machined on outer ring outer circumference

A: Factory preset light preload

Supply form: Supplied as fixed duplex set of two bearings; disassembly and random interchange with other single bearings are prohibited

Important reminder: The two bearings are matched one-to-one. Do not split and mix with other monoblock bearings. Install strictly according to matching marks. Preload cannot be adjusted by grinding end faces on site.

Suffix Comparison within Series

7015 ACD/P4A: Single bearing, 25° contact angle, P4 precision, no outer ring lubrication grooves

7015 ACD/P4DA: Factory duplex matched set, 25° contact angle, P4 precision, no outer ring grooves, light preload

7015 ACD/P4DGA: Factory duplex matched set, 25° contact angle, P4 precision, outer ring oil-air grooves, light preload (this model)

7015 ACD/P4DGB: Factory duplex matched set, 25° contact angle, P4 precision, outer ring oil-air grooves, medium preload

Comparative Reference Models

All steel single bearing without grooves: 7015 ACD/P4A

Duplex matched set without grooves, light preload: 7015 ACD/P4DA

Duplex matched set with outer ring oil-air grooves, light preload: 7015 ACD/P4DGA (this model)

Duplex matched set with outer ring oil-air grooves, medium preload: 7015 ACD/P4DGB

Core Basic Dimensions

Bore d: 75 mm

Outer diameter D: 115 mm

Width B: 20 mm

Structure: Single-row open-type angular contact ball bearing, factory duplex matched set of two units

Rolling element: High-precision bearing steel balls (all steel construction)

Ring material: High-carbon chromium bearing steel, ultra-precision mirror grinding on raceway

Cage: Machined solid brass cage

Outer ring feature: Continuous integrated oil-air circulation grooves on outer ring surface

Pre-filled lubricant: None

Delivery form: Packaged as complete duplex set with permanent matching marks

Note: Official dynamic load rating and limiting DN data can be requested from manufacturer.

Full Product Attributes

Contact form: Two-point contact

Number of rows: Single row, complete duplex matched assembly

Pairing property: Factory end-face ground duplex set with fixed matching marks; standard DB back-to-back mounting

Precision class: P4 high-speed super precision grade

Material: Inner & outer rings and rolling elements: high-carbon chromium bearing steel (all steel)

Seal structure: Open type, non-sealed

Special construction: Continuous oil-air circulation grooves on outer ring; factory pre-matching eliminates on-site pairing work; light preload balances rotational speed and rigidity

Note: ACD stands for 25° contact angle delivering higher axial rigidity than 15° variants, suitable for milling under moderate alternating axial loads. Machined solid brass cage features excellent heat resistance and low deformation under prolonged high-speed operation for heavy-duty finishing. Suffix D means factory pre-ground duplex set, greatly shortening spindle assembly time and ensuring consistent performance for mass production spindles. Suffix G outer ring oil grooves enable outer ring lubrication layout and simplify housing machining. Suffix A indicates light preload, optimized for high limiting speed and strict temperature control.

Default factory mounting layout is DB back-to-back. DF face-to-face or DT tandem arrangement must be confirmed during ordering. Splitting and random mixing will invalidate original matching accuracy. Open design fits oil-air lubrication and circulating oil lubrication; long-term continuous high-speed grease lubrication is not recommended.

2 Structure & Operating Characteristics

Japan NMT 7015 ACD/P4ADGA is premium all-steel 25° contact angle, P4 super precision factory duplex matched single-row angular contact ball bearing of 7015 series. Inner and outer rings are made of high-carbon chromium bearing steel with stabilized heat treatment to eliminate residual stress. Multi-stage mirror super-finishing on raceways reduces vibration amplitude and running noise during high-speed rotation.

Rolling elements are high-precision steel balls combined with machined solid brass cage with outstanding heat resistance, resisting transient temperature spikes generated in cutting and maintaining stable geometry during long-duration high-speed operation. Continuous pre-machined oil-air circulation grooves on outer ring allow even distribution of lubricant for outer-ring supply design and simplify housing oil channel processing. Two bearings are end-face ground and matched at factory with exclusive identification marks to avoid consistency deviations caused by on-site spacer pairing. Factory preset light preload delivers sufficient support rigidity while suppressing heat generation to achieve higher continuous rotating speed.

As standardized duplex support unit, it fits mass spindle production projects. Each complete set undergoes comprehensive inspection of rotational accuracy and matching parallelism. Widely applied to belt-driven mechanical spindles, external-motor high-speed engraving spindles, general CNC milling machines and grinding wheel spindles, sustaining stable rotational precision under continuous finishing conditions.

3 Core Performance Advantages

1. ACD 25° contact angle with machined solid brass cage: Sufficient axial rigidity, withstand moderate alternating milling loads. Heat-resistant low-deformation cage fits long continuous high-speed cutting.

2. G-type outer ring oil-air circulation grooves: Lubricant distribution along outer ring, supporting outer-ring lubrication layout and lowering housing machining difficulty.

3. D factory pre-ground duplex matched structure: Pre-matched with identification marks for easy assembly and consistent preload for mass spindle production.

4. A light factory preload: Balances rotational rigidity and temperature rise, ideal for precision spindles requiring high speed and low heat generation.

5. ISO P4 super precision grade: Strictly control radial and axial runout to maintain long-term high-precision cutting performance of spindles.

6. Open non-sealed construction: Zero seal friction loss, perfectly compatible with oil-air forced lubrication and circulating oil lubrication systems.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

P4 super precision duplex matched bearings must be assembled in constant-temperature dust-free clean workshops. Remove all burrs and metal debris on shaft and housing mating surfaces. Controlled thermal mounting method is recommended; open-flame heating is forbidden. Never strike bearing rings to prevent indentations on raceways.

Important reminder: 7015 ACD/P4ADGA is factory end-face ground duplex set. Do not split the set or interchange individual bearings with other single bearings. Assemble strictly following matching marks in standard DB back-to-back orientation. Protect outer ring circulation grooves during assembly to avoid debris blocking oil flow.

5.2 Pairing & Preload Instructions

Supply condition: Two bearings fixed end-face ground matched set with factory light A-preload.

Standard recommended mounting arrangement: DB back-to-back; notify manufacturer in advance if DF or DT layout is required.

Selection tips:

Mass-production spindles, outer ring oil-air supply, priority to speed and temperature control → Prioritize 7015 ACD/P4ADGA (light preload);

Heavier cutting loads requiring higher rigidity with acceptable temperature rise → Choose 7015 ACD/P4DGB (medium preload);

Housing with built-in oil passages without demand for outer ring grooves → Select 7015 ACD/P4DA;

Small-batch customized equipment requiring adjustable on-site preload → Adopt single bearing 7015 ACD/P4A with spacers.

Selection reference:

① All steel single bearing, no outer ring grooves, flexible pairing →7015 ACD/P4A

② All steel duplex set, no outer ring grooves, light preload →7015 ACD/P4DA

③ All steel duplex set, outer ring oil-air grooves, light preload →7015 ACD/P4DGA(this model)

④ All steel duplex set, outer ring oil-air grooves, medium preload →7015 ACD/P4DGB

5.3 Lubrication Matching Scheme

No pre-filled grease. Oil-air forced circulation lubrication or circulating oil lubrication system is recommended; long-duration high-speed grease lubrication is not advised. High-precision filters shall be installed in lubrication pipelines; hard foreign particles will scratch mirror raceway surfaces. Mixing lubricants of different brands or base oil types is prohibited. Regularly clear carbon deposits and contaminants inside outer ring grooves to guarantee smooth oil circulation. Maintain high lubricant cleanliness to reduce raceway fatigue wear risk for all-steel precision bearings.

5.4 Speed Parameter Note

Machined brass cage adapts to continuous operation within medium-to-high DN range. Light A-preload delivers higher limiting speed and lower overall temperature rise compared with medium preload variants. Preload level is fixed at factory; on-site adjustment via grinding bearing end faces is forbidden. The complete machine shall be equipped with efficient cooling system and sufficient speed safety margin. Open bearings have no built-in dust shield; bearing housing must be designed with reliable external sealing against dust and cutting fluid to prevent abrasive damage on rolling elements and raceways.

6 Daily Maintenance & Fault Troubleshooting

After complete set assembly, carry out multi-stage low-speed running-in, continuously monitor temperature rise and vibration indicators. Only raise rotating speed to rated high speed after all data stabilize. Continuously track spindle temperature variation during running-in phase. Regularly inspect external housing sealing integrity, oil-air pipeline pressure and flow rate, confirm outer ring grooves remain free of blockage for uniform lubricant supply.

When steady abnormal noise, rapid temperature rise or growing vibration occurs, check sequentially: lubricant cleanliness, outer ring groove clogging, assembly coaxiality, bearing mounting direction, excessive axial locking force, external impact load and foreign matter entering raceway.

Typical failure modes of duplex matched precision bearings include abrasive wear of raceways, surface pitting, local overheating caused by blocked grooves and uneven oil supply, destroyed matching benchmark due to wrong installation direction, excessive preload from over-tight locking and long-term overloaded operation. Conduct regular online monitoring of temperature and vibration to detect incipient bearing damage in advance and prevent unexpected spindle shutdown.