1 Complete Model & Code Explanation

Model: S71901 ACDGC/P4A

Code Definition

S71901: S prefix indicates stainless steel material, basic dimension of 719 miniature extra-light series angular contact ball bearing

ACD: Optimized internal geometry for 25° contact angle, improving axial load capacity and axial rigidity

GC: Full stainless steel rolling elements, integrated stainless steel construction for inner ring, outer ring and balls

P4A: ISO P4A super precision tolerance grade, high-precision single unit, supports DB/DF/DT assembly with precision spacers on site

Supply form: Individually packed single bearing without matching serial number; various paired structures can be configured with precision spacers

Important reminder: This bearing is supplied as single unit without factory duplex lapping. Direct assembly of two identical bearings cannot guarantee uniform preload. Precision spacers of corresponding accuracy grade are required, and spacer end lapping adjustment should be conducted when necessary to guarantee stable assembly precision.

Core Basic Parameters

Bore d: 12 mm

Outer diameter D: 24 mm

Width B: 6 mm

Nominal contact angle: 25°

Structure: Single-row open-type angular contact ball bearing, single unit supply

Internal design: ACD 25° contact angle load optimized structure

Material for rolling elements & rings: Martensitic stainless steel, all stainless construction

Ring structure: Integrated inner ring, integrated outer ring

Seal: Open type, no seals

Surface coating: Uncoated

Pre-filled lubricant: None

Contact type: Two-point normal contact

Number of rows: Single row

Duplex matching: No factory matched bearing set, no preset preload and axial clearance

Precision class: P4A

Net weight: 0.0082 kg

Indicative carbon footprint for new unit: 0.037 kg CO₂e

eClass code: 23-05-08-03

UNSPSC code: 31171531

Suffix Comparison within Series

S71901 ACDGC/P4A: 25° contact angle, all stainless steel, single unit P4A precision (this model)

S71901 CDGC/P4A: 25° contact angle, stainless steel general end face single unit

S71901 ACDGC/P4AQ: Factory duplex matched all stainless steel bearing set

S71901 ACEGC/P4A: 15° contact angle all stainless miniature bearing

71901 ACD/HC P4A: Standard bearing steel hybrid ceramic version without corrosion resistance

2 Structure & Operating Characteristics

Japan NMT S71901 ACDGC/P4A belongs to S719 series miniature all stainless steel super precision angular contact ball bearing, adopting ACD load-enhanced internal geometry with 25° contact angle. Inner rings, outer rings and rolling elements are made of martensitic stainless steel with dedicated stabilization heat treatment, balancing hardness, wear resistance and basic anti-rust performance. Raceways are processed by multi-stage ultra-precision mirror grinding to reduce rotation vibration and maintain stable high-precision operation.

The open non-sealed design eliminates sealing friction loss and supports grease lubrication and oil-air lubrication. The 25° contact angle delivers excellent axial load capacity and axial rigidity. Compared with conventional bearing steel, stainless steel effectively slows rust formation under high humidity, clean vapor environment and trace corrosive medium. As independent single bearing, equipment designers can select DB back-to-back, DF face-to-face or DT tandem layout according to machine layout, and set appropriate preload through precision spacers to satisfy miniature precision rotary mechanisms under humid and clean working conditions.

3 Core Performance Advantages

1. 25° ACD contact angle reinforced structure: High axial rigidity, superior capability to withstand axial thrust compared with 15° stainless steel bearings.

2. GC all-stainless integrated structure: Inner rings and balls adopt stainless steel with basic resistance against moisture and weak corrosive medium, suitable for clean and humid environments.

3. P4A miniature super precision tolerance: High rotational accuracy and low dimensional deviation, meeting precision rotation demands of high-end clean equipment.

4. Open uncoated non-sealed design: Eliminates sealing friction loss, compatible with grease lubrication and oil-air lubrication.

5. Excellent adaptability for clean applications: Low impurity precipitation, satisfying basic standards for medical, biochemical and semiconductor clean modules.

6. Flexible single-unit assembly: No restriction of factory pre-matching. Multiple layouts can be realized with precision spacers, suitable for prototype development and mass equipment manufacturing.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Assembly of miniature P4A super precision stainless steel bearings is recommended on constant-temperature dust-free clean workstations. Thoroughly remove burrs and dust on shaft journal and housing bore. Controlled thermal mounting is preferred. Direct striking on bearing rings is prohibited; impact will create permanent indentations on stainless steel raceways and damage rotational accuracy.

Important reminder: This is single bearing without factory duplex grinding. Uniform preload cannot be obtained by direct butt assembly of two bearings. Precision spacers of identical accuracy grade must be used, and spacer end lapping should be carried out if necessary.

5.2 Assembly Combination & Preload Instructions

Supply condition: Individually packed single bearing without matching serial number

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

Selection guidance:

Humid environment, clean equipment, anti-rust requirement, combined axial & radial load → prioritize S71901 ACDGC/P4A;

Dry condition, no corrosion risk, pursuing ultimate speed and load capacity → choose standard 719 bearing steel series;

Mass standardized production without on-site preload adjustment → purchase factory duplex matched S71901 ACDGC/P4AQ;

Mainly radial load and minor axial thrust → select 15° contact angle ACEGC stainless steel series;

Both electric corrosion risk and anti-rust demand → consult customized stainless hybrid ceramic version.

5.3 Lubrication Matching Scheme

No pre-filled grease inside bearing. Clean high-speed grease can be adopted for intermittent medium-low speed running; oil-air forced lubrication system is recommended for continuous medium-high speed operation. Precision filters shall be installed in lubrication pipelines, since hard particles easily scratch mirror raceways. Mixing lubricants of different brands and base oil types is forbidden. For humid working conditions, clean grease with anti-rust additives is suggested to extend service life.

5.4 Speed Application Notes

Rotational speeds listed in catalog are theoretical reference values. The limiting speed of stainless steel bearings is slightly lower than high-carbon chromium bearing steel variants. Sufficient safety margin shall be reserved during mechanical design with complete cooling construction. Open bearings have no built-in dustproof and waterproof function. External sealing structure must be equipped on equipment housing to prevent direct invasion of cleaning liquid, moisture and dust. Stainless steel provides basic rust protection and cannot be immersed in strong acid or alkali medium for long term.

6 Daily Maintenance & Fault Troubleshooting

Carry out low-speed staged running-in after assembly, continuously monitor temperature rise and vibration, and gradually increase speed to operating value once parameters stabilize. Stainless steel bearings own better rust resistance, yet pitting and wear will still occur under long-term lubrication failure.

Troubleshooting sequence for abnormal conditions: lubricant cleanliness, oil/grease supply rate, assembly coaxiality, preload magnitude, ingress of moisture & corrosive medium, impact load existence.

Typical failure modes of S719 series stainless steel precision angular contact bearings: indentations caused by foreign objects on raceways, wear induced by lubrication failure, surface rust from long-term condensation, fatigue spalling under excessive preload, permanent deformation due to shock load, uneven preload resulting from low-precision spacers. Establish regular maintenance and re-grease schedule to prevent abnormal noise and jamming of rotary shafts.