1 Complete Model & Code Explanation

Model: 7015 CDGC/P4A

Code Definition

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

CD: 15° nominal contact angle, machined solid brass cage balancing rotational speed and rigidity

GC: Factory end-ground duplex set, DB back-to-back arrangement with preset heavy preload

P4A: ISO P4 super precision grade with upgraded control standard for radial and axial runout

Supply form: Matched duplex set of two bearings with exclusive matching serial number

Important reminder: The matched duplex set must not be separated randomly. Cross mixing with bearings from other matching groups is prohibited. After separation, matching accuracy and factory preset preload will be permanently lost and cannot be restored. Only complete set installation is supported; on-site modification to DB/DF/DT layout is unavailable.

Suffix Comparison within Series

7015 CD/P4A: Single bearing, 15° contact angle, all steel balls, P4A precision, without duplex matching

7015 CDGA/P4A: Duplex set, 15° contact angle, all steel balls, GA light preload DB pairing

7015 CDGB/P4A: Duplex set, 15° contact angle, all steel balls, GB medium preload DB pairing

7015 CDGC/P4A: Duplex set, 15° contact angle, all steel balls, GC heavy preload DB pairing (this model)

7015 CDGA/HCP4A: Duplex set, 15° contact angle, HC silicon nitride ceramic balls, GA light preload DB pairing

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, supplied as two matched DB back-to-back units

Rolling element: High chromium steel balls (standard all-steel configuration)

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

Cage: Machined solid brass cage

Outer ring feature: Standard plain outer ring without integrated oil-air lubrication grooves

Pre-filled lubricant: None

Delivery form: Packaged as complete duplex set, engraved with unique matching serial number

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, factory pre-assembled as DB back-to-back duplex set

Pairing property: Permanently matched via factory end grinding, GC heavy preload; separation and random mixing forbidden

Precision class: P4A enhanced ISO P4 super precision high-speed grade

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

Seal structure: Open type, non-sealed

Special construction: Factory preset heavy preload delivers superior axial rigidity; precision end grinding ensures consistent preload

Note: CD stands for 15° small contact angle with good radial rigidity and higher limiting speed compared with 25° contact angle bearings. GC heavy preload greatly improves axial stiffness against alternating cutting loads, accompanied by slightly reduced maximum speed and higher heat generation compared with GA and GB preload grades. Open construction supports oil-air lubrication and circulating oil lubrication; long-term continuous high-speed grease lubrication is not recommended. All-steel structure features cost advantages over hybrid ceramic bearings, suitable for mass-production spindle projects requiring high rigidity with moderate budget and non-extreme rotational speed requirements.

2 Structure & Operating Characteristics

Japan NMT 7015 CDGC/P4A is P4A super precision pre-matched duplex angular contact ball bearing of 7015 series with 15° contact angle and all-steel rolling elements. Inner and outer rings adopt high-carbon chromium bearing steel with stabilized heat treatment to eliminate residual stress. Raceways are processed by repeated mirror super-finishing to achieve excellent rotational accuracy and low vibration.

Rolling elements are standard high-carbon chromium steel balls with stable load capacity and decent impact resistance. The matched machined solid brass cage features low thermal deformation, suitable for long-term nonstop cutting operation.

Two bearings are end-ground and assembled into a DB back-to-back set at factory with preset GC heavy preload. Each set carries exclusive matching serial number. Preload level remains consistent after delivery. No additional spacer processing or selection is required during assembly, enabling direct installation of complete sets. Heavy preload effectively restrains axial play of spindles, withstands alternating cutting loads and improves dimensional stability in finishing processes.

The outer ring is plain standard design without integrated lubrication grooves, compatible with spindles adopting built-in housing oil channels. Open non-sealed structure cooperates with external oil-air lubrication system for continuous oil supply and cooling.

3 Core Performance Advantages

1. CD 15° small contact angle design: Excellent radial rigidity, moderate friction level, delivering higher limiting speed than wide contact angle bearings for medium & high-speed cutting.

2. GC factory end-ground heavy preload DB duplex set: Significantly enhanced axial rigidity, suppress axial movement and resist alternating cutting loads.

3. All-steel rolling element configuration: Mature and stable technology, balanced load performance, lower procurement and maintenance cost than hybrid ceramic bearings.

4. P4A enhanced super precision grade: Strict control over radial and axial runout, guaranteeing surface finish and dimensional consistency for finished workpieces.

5. Open non-sealed construction: Eliminates seal friction loss, fully compatible with oil-air forced lubrication and circulating oil cooling lubrication systems.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

P4A super precision 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 avoid raceway indentations and damage to matching precision.

Important reminder: 7015 CDGC/P4A is factory permanent duplex matched set. Splitting two bearings for individual use or interchanging with same-model bearings from other batches is strictly prohibited. Once separated, end matching accuracy and preset preload cannot be recovered permanently.

5.2 Pairing & Preload Instructions

Supply condition: Duplex set of two bearings in DB back-to-back layout, GC heavy preload, marked with matching serial number.

Fixed mounting form: DB back-to-back fixed by factory assembly; conversion to DF/DT layout on site is impossible.

Selection tips:

Medium & high-speed cutting, alternating loads, high axial rigidity demand → Prioritize 7015 CDGC/P4A;

Ultra-high continuous speed, strict temperature control, light cutting → Select GA light preload ceramic ball bearing 7015 CDGA/HCP4A;

Moderate loads, balance between speed and rigidity → Adopt GB medium preload all-steel duplex set 7015 CDGB/P4A;

Prototype development with flexible preload adjustment → Choose single bearing 7015 CD/P4A;

Low speed heavy loads, large axial force → Select bearings with 25° contact angle.

Selection reference:

① Single bearing, 15°, all steel balls →7015 CD/P4A

② Duplex DB light preload, 15°, all steel balls →7015 CDGA/P4A

③ Duplex DB medium preload, 15°, all steel balls →7015 CDGB/P4A

④ Duplex DB heavy preload, 15°, all steel balls →7015 CDGC/P4A(this model)

⑤ Duplex DB light preload, 15°, HC ceramic balls →7015 CDGA/HCP4A

5.3 Lubrication Matching Scheme

No pre-filled grease. Oil-air forced circulation lubrication is preferred; circulating oil lubrication is also acceptable. Long-duration continuous high-speed grease lubrication is not recommended. High-precision filters must be installed in lubrication pipelines. Hard particles will easily scratch mirror raceway surfaces. Mixing lubricants of different base oils or brands is forbidden. Replace filter elements regularly to maintain lubricant cleanliness and extend bearing service life.

5.4 Speed Parameter Note

GC heavy preload structure greatly strengthens spindle rigidity yet generates higher internal friction heat compared with GA and GB preload grades, which reduces allowable limiting DN value. It fits medium & high-speed continuous cutting; long-term operation exceeding rated speed easily causes overheating. The complete machine must be equipped with efficient cooling system and sufficient speed safety margin. Open bearings have no built-in dust protection. Bearing housing must adopt reliable external sealing against dust and cutting fluid to prevent raceway damage caused by foreign matter intrusion.

6 Daily Maintenance & Fault Troubleshooting

After full set assembly, perform multi-stage low-speed running-in, continuously monitor temperature rise and vibration data. Only raise rotating speed to rated working speed once all indicators stabilize. Track spindle temperature variation closely during running-in. Regularly inspect external housing sealing condition, lubrication pipeline pressure and flow rate to maintain stable continuous oil supply.

If persistent abnormal noise, rapid temperature rise or growing vibration occurs, check sequentially: lubricant cleanliness, assembly coaxial precision, excessive axial locking force, external impact load, cutting fluid or dust intrusion into bearing interior.

Typical failure modes of heavy preload all-steel matched bearings include raceway fatigue spalling, abrasive wear, overheating due to insufficient lubrication, edge loading from misalignment, preload overload caused by excessive tightening. Establish regular online monitoring of temperature and vibration to detect early damage and avoid unexpected spindle shutdown.