1 Complete Model & Code Explanation

Model: S71901 ACDGA/HCP4A

Code Definition

S71901: Basic dimension specification of 719 miniature extra-light series angular contact ball bearing. Prefix S stands for stainless steel base material

ACD: High-load D-type optimized internal geometry with 25° contact angle to improve axial load capacity and system rigidity

GA: Open non-sealed structure without built-in grease, compatible with external circulating lubrication such as oil-air lubrication

HC: High corrosion-resistant stainless steel material, with excellent resistance to condensation and mild moisture rust compared with standard bearing steel

P4A: ISO P4A super precision tolerance grade, high-precision single unit, supporting 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 universal matchable open single unit without factory duplex lapping. When assembling two bearings with precision spacers, adjust preload to grade A standard by measured load to achieve higher system rigidity. The load capacity of HC stainless steel material is slightly lower than bearing steel versions. For heavy-load working conditions, priority should be given to standard steel type 71901 ACDGA/P4A.

Core Basic Parameters

Bore d: 12 mm

Outer diameter D: 24 mm

Width B: 6 mm

Nominal contact angle: 25°

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

Internal design: ACD high-load D-type structure with 25° contact angle

Contact form: Two-point standard contact

Number of rows: Single row

Ring structure: Integrated inner ring, integrated outer ring

Seal arrangement: Open design, no sealing rings

Seal type: None

Base material: HC corrosion-resistant stainless steel

Surface coating: Uncoated

Pre-installed lubricant: No pre-filled grease, lubrication system to be configured separately

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: P4A

Basic dynamic load rating: 2.35 kN

Basic static load rating: 1.08 kN

Speed reference: Contact manufacturer for attainable rotational speed reference data

Net weight: 0.0098 kg

Indicative carbon footprint for new unit: 0.036 kg CO₂e

eClass code: 23-05-08-04

UNSPSC code: 31171531

Suffix Comparison within Series

S71901 ACDGA/HCP4A: HC stainless steel, 25° contact angle, open type without seal, no pre-filled grease, universal matchable single unit P4A precision, Grade A preload (this model)

71901 ACDGA/P4A: Standard bearing steel open bearing with Grade A preload

S71901 ACDGB/HCP4A: HC stainless steel double-sided non-contact seal, pre-greased, Grade B preload

S71901 ACDGC/HCP4A: HC stainless steel open single bearing with Grade C preload

S71901 ACDGAQ/HCP4A: HC stainless steel factory duplex matched open bearing set

S71901 ACEGA/HCP4A: HC stainless steel 15° contact angle open miniature bearing with Grade A preload

2 Structure & Operating Characteristics

Japan NMT S71901 ACDGA/HCP4A belongs to 719 series HC stainless steel super precision angular contact ball bearing. It adopts ACD high-load D-type raceway geometry with 25° contact angle to enhance axial rigidity, suitable for intermittent high-speed and slightly humid operating conditions. Inner and outer rings are integrally formed, raceways processed by ultra-precision mirror grinding to reduce vibration and noise during high-speed operation.

The bearing adopts GA open construction without friction resistance caused by sealing rings, achieving higher attainable speed than sealed bearings. Without pre-filled grease, it is specially designed for external circulating lubrication systems, compatible with oil-air, oil injection and oil mist lubrication to continuously remove heat generated in high-speed operation.

As universal matchable single bearing, multiple duplex configurations can be flexibly assembled with Grade A preload. Grade A preload delivers larger axial preload force, strong anti-deformation performance and higher limit of rotary positioning accuracy, more suitable for intermittent operation pursuing high rigidity, while temperature rise is relatively high under long continuous running. HC stainless steel provides basic rust protection and can resist condensation and mild moisture in clean environments, yet not applicable for acid, alkali or heavy salt spray severely corrosive conditions. Compared with same-size bearing steel bearings, material hardness and rated load decrease moderately, not fit for continuous heavy-duty cutting applications.

3 Core Performance Advantages

1. ACD high-load D-type 25° contact angle structure: Excellent axial rigidity and stable operation under combined loads.

2. GA open non-sealed design: Eliminates friction loss caused by seals, outstanding attainable speed and compatible with various forced circulating lubrication systems.

3. HC corrosion-resistant stainless steel substrate: Basic anti-rust capability, tolerates condensation and slight moisture in clean environment and reduces rust risk during shutdown.

4. No pre-installed lubricant: Supports independent configuration of oil mist, oil-air and oil injection lubrication to satisfy high-speed heat dissipation requirements.

5. P4A super precision tolerance: High dimension consistency, low rotary runout to guarantee positioning accuracy of precision equipment.

6. Grade A preload free duplex solution: Sufficient preload capacity, strong resistance to axial impact deformation and excellent positioning precision.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Assembly of P4A open stainless steel super precision bearings is recommended to be completed in constant-temperature, clean and dust-free workshops to control dust and impurities. Thermal mounting is preferred; direct striking on bearing raceways is forbidden. Open bearings have no sealing protection for raceways. Avoid bare hand contact with raceways during assembly to prevent pollutant adhesion.

Important reminder: No factory duplex grinding 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 distribution.

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:

Intermittent high speed, clean humid/condensation environment requiring basic rust resistance → prioritize S71901 ACDGA/HCP4A;

Dry environment with priority on load capacity → select standard bearing steel 71901 ACDGA/P4A;

Humid environment requiring no continuous external oil supply → choose sealed Grade B preload S71901 ACDGB/HCP4A;

Low load and limited budget → adopt Grade C preload S71901 ACDGC/HCP4A;

Mass production standardized equipment without on-site preload adjustment → factory duplex matched S71901 ACDGAQ/HCP4A;

Predominantly radial load with minor axial thrust → select 15° contact angle S71901 ACEGA/HCP4A;

Salt spray, acid and alkali severely corrosive conditions → higher anti-corrosion bearing solution is required, this model cannot be used.

5.3 Lubrication Matching Scheme

No lubricant is filled inside bearing upon delivery. Supporting lubrication system must be activated timely after assembly. Oil-air or oil mist lubrication is recommended for high-speed working conditions; long-life grease suitable for stainless steel can be refilled regularly for intermittent medium-low speed operation. The open structure cannot block dust, so lubrication pipelines must be equipped with filters to avoid hard particles invading raceways. Mixing greases and oils of different base oils or brands is prohibited. Avoid lubricants containing corrosive additives for stainless steel bearings.

5.4 Speed & Environmental Application Notes

The open design features low friction resistance and supports higher operating speeds. Detailed speed parameters can be obtained from the manufacturer. Though made of HC stainless steel, it only owns basic moisture resistance. It cannot be directly used in environments with salt spray, acid-alkali liquid splash or strongly corrosive gas. External cavity sealing protection is suggested when massive dust exists.

6 Daily Maintenance & Fault Troubleshooting

Carry out low-speed staged running-in after assembly, continuously monitor temperature rise and vibration indicators. Do not increase to working speed until operation stabilizes. Open bearings fully rely on external lubrication systems. Lubrication interruption will easily lead to raceway abrasion and surface scoring.

Grade A preload brings remarkable rigidity advantage, yet preload relaxation tends to occur under long-term high-temperature continuous operation. Periodic re-measurement of preload load is advised. Stainless steel bearings are not prone to atmospheric rust, but foreign particle accumulation and lubrication failure will still result in pitting corrosion and fatigue spalling.

Common abnormal triggers: indentation on raceway caused by foreign objects, dry grinding due to insufficient lubrication, improper preload setting, excessive coaxiality deviation between shaft and housing, long-term exposure beyond allowable corrosive environment.

Formulate regular inspection schedule for lubrication system, monitor oil pressure, flow rate and oil temperature, to prevent accuracy degradation and shaft seizure in advance.