1 Complete Model & Code Explanation

Model: 71901 CDGA/HCP4A

Code Definition

71901: Standard specification of 719 bearing steel miniature extra-light series angular contact ball bearing

CD: Standard raceway geometry with 30° contact angle, strong axial load capacity suitable for combined loads with large axial thrust

GA: Open non-sealed construction without built-in grease, compatible with external oil-air, oil mist and oil injection circulating lubrication system

HCP4A: Upgraded ISO P4A ultra-high precision tolerance grade, superior rotary accuracy to standard P4A, single unit supports field free duplex assembly of DB/DF/DT

Supply form: Individually packed single bearing for universal matching; preload grade A, preload adjusted via measured load method

Important reminder: This bearing is open single unit without factory duplex lapping. When assembling two bearings with precision spacers, adjust preload to grade A standard by measured load. Grade A preload delivers high axial rigidity for high-speed and high-precision positioning, yet generates higher temperature rise compared with Grade B preload. The open design offers no dust-proof or moisture-proof performance; equipment must be equipped with housing seal and clean lubrication system. It cannot be directly used in dusty, humid or condensation environments. Bearing steel version has higher load rating than stainless steel equivalent without rust resistance; rust occurs rapidly once lubrication is interrupted. Long-term operation only relying on single filling grease is not recommended; continuous external oil supply is preferred.

Core Basic Parameters

Bore d: 12 mm

Outer diameter D: 24 mm

Width B: 6 mm

Nominal contact angle: 30°

Structure: Single-row angular contact ball bearing, supplied as single unit

Internal design: CD standard raceway structure with 30° contact angle

Contact form: Two-point standard contact

Number of rows: Single row

Ring structure: Integrated inner ring, integrated outer ring

Seal arrangement: Open type, no seal

Seal type: Open design without sealing component

Base material: High carbon chromium bearing steel

Surface coating: Uncoated

Pre-installed lubricant: No pre-filled grease, depends on continuous external oil supply

Duplex capability: Universal matchable bearing, available for back-to-back (<>), face-to-face (><), tandem (>>) layout; no factory preset duplex arrangement, grade A axial clearance/preload adjusted by measured load

Precision class: HCP4A (upgraded ISO P4A ultra-high precision grade)

Basic dynamic load rating: 2.82 kN

Basic static load rating: 1.31 kN

Speed reference: Contact manufacturer for attainable rotational speed reference data

Net weight: 0.0105 kg

Indicative carbon footprint for new unit: 0.039 kg CO₂e

eClass code: 23-05-08-04

UNSPSC code: 31171531

Suffix Comparison within Series

71901 CDGA/HCP4A: Bearing steel, 30° contact angle, open non-sealed, no pre-filled grease, HCP4A ultra-high precision, Grade A preload (this model)

71901 CDGB/HCP4A: Bearing steel double-sided non-contact sealed bearing with Grade B preload

71901 ACDGA/HCP4A: Bearing steel 25° contact angle open bearing with Grade A preload for high speed

71901 CDGAQ/HCP4A: Bearing steel factory duplex matched open bearing set

S71901 CDGA/P4A: Martensitic stainless steel open bearing P4A precision Grade A preload with basic rust resistance

71901 CDGC/HCP4A: Open single bearing with Grade C light preload focusing on low temperature rise

2 Structure & Operating Characteristics

Japan NMT 71901 CDGA/HCP4A belongs to 719 series bearing steel super precision angular contact ball bearing, adopting CD 30° contact angle raceway configuration with excellent axial load capacity and balanced radial load capacity, ideal for rotary spindles with high proportion of axial load under high-speed conditions. Inner and outer rings are integrally formed, raceways processed with ultra-precision mirror grinding to reduce vibration during high-speed rotation, improve rotary accuracy and mitigate heat generation.

GA open non-sealed design completely eliminates friction loss and airflow disturbance caused by sealing parts, achieving remarkably higher limiting speed than sealed bearings of identical size, which makes it the preferred choice for high-speed spindle systems. No lubricant is pre-filled inside upon delivery; continuous lubricating oil must be supplied externally via oil-air, oil mist or high-pressure injection to provide sustained cooling and lubrication. The open structure avoids grease washing failure, perfectly matching mainstream industrial high-speed circulating lubrication schemes.

As universal matchable single bearing, multiple duplex configurations can be flexibly assembled with Grade A preload. Grade A preload provides sufficient axial rigidity to restrain shaft axial float during high-speed rotation; the disadvantage is higher temperature rise under identical working conditions than Grade B preload, demanding higher standards for lubrication and cooling systems. Bearing steel material features superior mechanical strength and load rating compared with stainless steel bearings without any rust resistance; rust spots easily emerge on raceways once lubrication stops or moisture invades. Without built-in protection, it cannot be exposed to dust and humid air without housing.

3 Core Performance Advantages

1. CD 30° contact angle raceway structure: Outstanding axial load capacity for high-speed combined loads dominated by axial thrust.

2. GA open non-sealed construction: Remove sealing friction loss for higher limiting speed, compatible with oil-air and oil mist circulating lubrication.

3. HCP4A ultra-high precision tolerance: Upgraded P4A grade with smaller rotary runout, meeting high-precision positioning requirements of premium spindles.

4. Grade A standard preload solution: Adequate axial rigidity to suppress high-speed shaft float, suitable for high-precision continuous positioning processing equipment.

5. Premium bearing steel substrate: Higher basic dynamic and static load rating and stronger mechanical rigidity than stainless steel bearings of equal dimension.

6. Compatible with continuous external oil supply system: No pre-filled grease, eliminating grease aging caused by flushing from circulating oil, suitable for long-term continuous high-speed operation.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Assembly of HCP4A ultra-high precision open angular contact bearings must be completed in constant-temperature, dust-free clean workshops with strict dust control. Thermal mounting is recommended; direct impact on inner/outer rings and raceway areas is forbidden. Raceways of open bearings have no protection; avoid direct manual contact during assembly to prevent initial rust induced by sweat.

Important reminder: No factory duplex lapping for open single bearings. When two bearings are combined, match precision spacers and adjust preload to Grade A standard via measured load to ensure uniform load sharing and avoid abnormal vibration at high speed.

5.2 Assembly Combination & Preload Instructions

Supply condition: Independent open single bearing, universal for duplex arrangement

Optional layout: DB back-to-back / DF face-to-face / DT tandem

Preload control method: Measured load, grade A preload

Selection guidance:

Clean dry environment, equipped with oil-air/oil mist external lubrication, pursuing high speed and high rigidity → prioritize 71901 CDGA/HCP4A;

Equal high-speed application, priority on temperature control with moderate rigidity requirement → select 71901 CDGC/HCP4A;

Minor dust exists, complicated housing protection hard to arrange, built-in seal required → select 71901 CDGB/HCP4A;

Predominantly radial load, higher limiting speed required → select 25° contact angle 71901 ACDGA/HCP4A;

Mass standardized spindles without on-site preload adjustment → factory duplex matched 71901 CDGAQ/HCP4A;

Slightly humid environment with condensation, basic rust protection needed and complete housing seal unavailable → select stainless steel S71901 CDGA/P4A;

No external circulating oil supply, only long-life grease maintenance → this open model is prohibited, switch to sealed suffix bearing.

5.3 Lubrication Matching Scheme

71901 CDGA/HCP4A adopts open structure without factory pre-filled grease. External continuous oil supply system is mandatory. Oil-air lubrication, oil mist lubrication or low-pressure injection cooling lubrication are recommended. Long-term high-speed operation relying merely on one-time grease filling is forbidden, which easily leads to lubrication failure and premature bearing seizure. Select low-viscosity high-speed spindle special lubricating oil, regularly monitor oil cleanliness to prevent impurities entering raceways and triggering abrasion.

5.4 Speed & Environmental Application Notes

Without sealing resistance, its limiting speed outperforms sealed bearings of same specification. No built-in dust-proof, moisture-proof and anti-rust capability. Operating environment must remain dry and clean, and equipment housing shall be fitted with complete dust sealing structure. Bare installation in dusty, humid, condensation or corrosive gas environments is strictly prohibited. Shut down immediately once lubrication system fails and oil supply stops to avoid dry friction, overheating and rust within short time.

6 Daily Maintenance & Fault Troubleshooting

Carry out low-speed staged running-in after assembly, continuously monitor vibration and temperature rise, and gradually increase speed to rated level after stable operation. Ensure stable oil supply of lubrication system all the time, regularly inspect oil circuit filters to block impurities invading bearings.

Grade A preload excels in rigidity, yet preload force is sensitive to temperature variation; temperature fluctuation during long-hour high-speed operation changes preload status. Regular recheck of rotary accuracy and preload load is suggested for high-end spindles. Bearing steel is vulnerable to rust once contacting moisture; supply a small amount of lubricating oil continuously or implement dry sealing protection for long-term storage after shutdown.

Common abnormal triggers: raceway contamination and pitting during assembly, dry friction caused by lubrication system oil cut-off, persistent overheating from excessive Grade A preload, poor coaxiality between shaft and housing, abrasive wear due to dust entering raceways, rust after standing in humid environment when shutdown.

Formulate periodic plans for lubrication system inspection, oil replacement and accuracy recheck to prevent high-speed abnormal noise, vibration amplification, accuracy drift and bearing seizure in advance.