1 Complete Model, Dimensions, Loads & Technical Parameters

Full Model: 7202 A/P4

Model Code Explanation

7202: Standard size of 72 series medium precision spindle, balancing installation space and load capacity, widely adopted for small and medium CNC machine tools; A: 30° large contact angle with outstanding axial rigidity, suitable for working conditions with high axial load proportion; P4: P4 precision tolerance grade to meet the rotary accuracy requirements of CNC spindles. It is a single open bearing without factory matching or preload, supporting free combined assembly according to equipment conditions.

Standard Dimension Parameters

Bore d: 15 mm

Outer diameter D: 35 mm

Width B: 11 mm

Contact angle: 30°

Load Performance Data

Basic dynamic load rating Cr: 9.82 kN

Basic static load rating C0r: 5.38 kN

Limit Speed Reference

Grease lubrication: 43000 r/min

Oil-air lubrication: 64000 r/min

Boundary Installation Dimensions

Inner ring large end shoulder diameter: 20.2 mm

Outer ring large end shoulder diameter: 29.8 mm

Min chamfer r₁,₂: 0.6 mm

Min chamfer r₃,₄: 0.4 mm

Full Product Attributes

Contact style: two-point contact

Row: single row

Race structure: integrally formed inner and outer rings with balanced structural rigidity

Internal design: A-type 30° contact angle optimized raceway to enhance axial load capacity

Matching feature: single unit without preset clearance and preload

Matching layout: back-to-back, face-to-face, tandem optional

Precision class: P4 precision grade

Material: high-purity vacuum degassed bearing steel with excellent contact fatigue resistance

Coating: uncoated, compatible with all types of spindle oil and grease

Seal: open seal-free structure

Pre-filled lubricant: none, lubrication scheme optional on demand

Speed note: Actual speed is affected by lubrication mode, preload, assembly coaxiality and load. Consult NMT technical team for complex working condition parameters.

2 Structure & Operating Characteristics

Japan NMT 7202 A/P4 is a P4 grade precision single angular contact bearing with 30° contact angle, developed for small and medium CNC processing equipment. Traditional bearings with small contact angles suffer insufficient axial rigidity and cannot handle heavy cutting and high axial cutting force. Adopting 30° A-type large contact angle, this model greatly improves axial load capacity and anti-overturning performance, achieving higher stability under composite loads such as milling and drilling.

Inner and outer rings are integrally forged and treated with multiple stress relief stabilization heat treatment to reduce dimensional creep risk during long-term high-speed operation. Super-precision mirror finishing on raceways reduces rolling friction and temperature rise while maintaining stable rotary accuracy. The open clean structure eliminates friction loss caused by seals and maximizes speed potential, supporting both high-speed oil-air lubrication and conventional grease lubrication.

As a standard single bearing, it is not limited by fixed matching methods. Manufacturers can freely select assembly forms and adjust preload according to spindle structure, adapting to working conditions from light finishing to medium-load cutting. It features strong versatility and convenient standardized inventory management.

3 Core Performance Advantages

1. 30° Large Contact Angle, Excellent Axial Rigidity: Higher axial load capacity than small contact angle bearings, ideal for drilling and end milling with heavy axial loads.

2. P4 Precision Grade, Stable Rotary Accuracy: Strictly controlled dimensional tolerance and runout reduce spindle machining chatter and improve workpiece surface quality.

3. Integral Race Structure, Strong Deformation Resistance: Uniform stress distribution resists start-stop impact and alternating cutting loads and slows precision degradation.

4. Open Seal-Free Design, Lower Friction Loss: No sealing resistance leads to better temperature control at high speed and compatibility with various lubrication systems.

5. Flexible Free Matching Scheme: Single unit supports three mainstream assembly layouts to meet diverse rigidity and load requirements of spindle designs.

6. High-Quality Bearing Steel Substrate, Long Service Life: High-purity raw materials reduce inclusions and lower risks of raceway pitting and fatigue spalling, suitable for long continuous processing.

4 Typical Application Scenarios

4.1 Small & Medium CNC Machining Spindles: CNC engraving & milling spindles, small vertical machining center spindles, high-speed drilling spindles, small mold engraving spindles for medium-high speed milling and drilling finishing.

4.2 Precision Grinding Heads for Grinding Machines: Internal grinding heads, small external grinding spindles, tool grinding rotary units for high-precision, low-vibration grinding processes.

4.3 Automatic High-Speed Rotary Mechanisms: Precision rotary tables for automation equipment, small robot rotary joints, precision indexing devices, rotary toolings for online inspection.

4.4 High-Speed Precision Motor Equipment: High-power high-speed spindle motors, variable frequency precision drive motors, built-in high-speed rotary assemblies for testing instruments.

4.5 General Precision Mechanical Equipment: Precision textile rotary shafts, rotary mechanisms of packaging machinery, core rotary components of small printing equipment and various light industry high-precision rotary devices.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

P4 precision bearings should be assembled in clean surroundings. Remove impurities on shaft journals, housing bores and spacer surfaces to avoid hard particle damage to raceways. Thermal mounting is recommended. Direct impact on bearing rings and rolling surfaces is forbidden. Appropriately control interference fit; excessive interference will cause bearing overheating and seizure. Use bearings from the same batch for combined assembly to guarantee consistent operation.

5.2 Matching Layout & Preload Instructions

7202 A/P4 has no factory preload or preset clearance; preload is adjusted by assembly spacers. Back-to-back layout delivers optimal anti-overturning capacity for overhanging spindle machining. Face-to-face layout provides superior positioning accuracy, suitable for precision drilling and positioning processes. Tandem layout maximizes axial load capacity for continuous unidirectional axial loads. Light preload is recommended for high-speed conditions; moderate preload can be adopted for heavy cutting while monitoring temperature rise to prevent thermal failure.

5.3 Lubrication Matching Solutions

No pre-filled lubricant inside the bearing. Oil-air lubrication system is suggested for high-speed applications to reach the limit speed of 64000 r/min. Consecutive processing equipment can adopt high-temperature resistant special grease for high-speed spindles. Mixing different lubricants is prohibited. Thoroughly clean residual grease before lubricant replacement to avoid lubrication failure.

5.4 Speed Parameter Note

The listed limit speeds are reference values under standard environment, moderate preload and clean lubrication. Operating speed shall be reduced accordingly when load, preload or ambient temperature increases. Contact NMT technicians for customized assembly and lubrication schemes for specific equipment.

6 Daily Maintenance & Fault Troubleshooting

No-load trial run is mandatory after assembly. Continuously monitor temperature rise, vibration and noise before cutting operation. The open structure has no built-in dust or coolant protection. External sealing protection must be installed at the spindle end if cutting fluid, dust and metal chips exist in working environment.

Carry out regular lubrication maintenance to replenish or replace lubricants on schedule and maintain effective oil film on raceways. Once continuous abnormal noise, accuracy drop or excessive temperature occurs during operation, prioritize checking lubrication system, assembly coaxiality and foreign particle intrusion. Avoid long-term impact load exceeding rated value to prevent permanent raceway damage.