7902 Angular Contact Ball Bearing (ZrO₂)

7902 Angular Contact Ball Bearing (ZrO₂) is a high-precision super-thin-section full ceramic angular contact ball bearing. Made of yttria-stabilized zirconia (Y-TZP), it handles combined radial and axial loads with ultra-compact dimensions, offering excellent corrosion resistance, high hardness, low friction, and complete electrical insulation. Suitable for high-speed applications requiring extreme cleanliness, chemical resistance, or operation in vacuum and high-temperature environments.

◆ Basic Dimensions and Weight

Model 7902. Dimensions in mm, weight in kg.

Mounting dimensions: da min = 17.5 mm, Da max = 25.5 mm, ra max = 0.3 mm.
Reference weight: 0.012 kg (ZrO₂ full ceramic). This ultra-lightweight characteristic (only 12 grams) makes it particularly suitable for high-speed rotating systems where reducing rotating mass is critical.[reference:0][reference:1]

◆ Material Structure and Properties

Material composition: Yttria-stabilized zirconia (ZrO₂, Y-TZP) — sintered advanced ceramic with yttria (Y₂O₃) as stabilizing agent. Density ~6.0 g/cm³, Vickers hardness ≥1300 HV10, flexural strength ≥1000 MPa, thermal expansion coefficient approximately 10.5×10⁻⁶/K (closely matching that of steel, facilitating integration into existing assemblies). Dielectric strength >15 kV/mm, completely non-magnetic and electrically insulating. PTFE cage standard; PEEK cage available for higher temperature applications. Full ceramic construction (both rings and rolling elements made from ZrO₂) provides complete chemical inertness and allows dry running without lubricants.[reference:2][reference:3]

◆ Core Performance Advantages

● Ultra-Compact Super Thin Section Design – With a 15 mm bore, 28 mm outer diameter, and only 7 mm width, this bearing is optimized for space-constrained precision systems. Despite the ultra-thin cross-section, the angular contact geometry ensures effective directional load control and rigidity when configured with appropriate preload.

● Complex Load Capacity – Fixed contact angle (typically 15°, 25°, or 40°) handles simultaneous radial and axial loads. Permissible axial load (Pa) up to approximately 1.93 kN for steel equivalents. The full ceramic version maintains similar load distribution principles while offering superior environmental resistance.[reference:4][reference:5]

● Extreme Temperature Resistance – ZrO₂ ceramic bearings operate reliably from sub-zero conditions (down to −70°C or lower) up to approximately 600°C depending on cage selection. For high-temperature ceramic-on-ceramic full-complement designs (cage-less), continuous operation up to 400–500°C is feasible. PTFE cage suitable up to ~260°C; PEEK cage suitable up to ~300°C; for the highest temperatures, cage-less (full complement) designs are recommended.[reference:6][reference:7]

● High-Speed Capability – The lower density of ZrO₂ ceramic (approximately 40–60% lighter than steel) reduces centrifugal forces on rolling elements at high rotational speeds, enabling higher maximum rotational speeds and lower friction-related heat generation compared to equivalent steel bearings. Steel-equivalent 7902 grease-lubricated versions can reach up to 53,000–67,000 rpm; oil-air lubrication can achieve up to 67,000–81,400 rpm.[reference:8][reference:9][reference:10]

● Corrosion and Chemical Resistance – ZrO₂ exhibits excellent resistance in most acidic and alkaline environments, with corrosion tests showing surface degradation <0.05 mm/year in pH 1–14 media. The fully ceramic construction withstands exposure to solvents, saltwater, and aggressive cleaning agents that would rapidly degrade conventional steel bearings. FDA/USDA compliant grades available for food processing applications.[reference:11][reference:12]

● Electrical Insulation & Non-Magnetic – As a full ceramic bearing, the 7902 is completely non-conductive (dielectric strength >15 kV/mm) and non-magnetic. This prevents electrical arcing damage and electrolytic corrosion in motors, generators, and other electrical equipment, and ensures compatibility with sensitive electromagnetic systems such as MRI equipment.[reference:13]

● High-Precision Grade – Available in precision grades up to P4/P5 (ABEC-7/ABEC-5 equivalents), providing high rotational accuracy and smooth, stable operation for precision equipment requiring consistent positioning and low vibration.[reference:14]

◆ Application Areas

● High-Speed Spindles (Ultra-Compact Size) – For small CNC spindles, PCB drilling machines, grinding spindles, and precision machining centers where space is limited and rotational speeds are high. The 15×28×7 mm form factor is particularly well-suited for applications requiring high rpm in a compact envelope.[reference:15]

● Semiconductor & Cleanroom Manufacturing – Vacuum chamber equipment, wafer handling robots, and lithography systems. Full ceramic construction eliminates particle generation from lubricants, while non-magnetic and non-conductive properties prevent current-induced damage to sensitive electronic components.[reference:16]

● Medical and Dental Equipment – Surgical handpieces, dental drills, laboratory centrifuges, and precision diagnostic instruments. The bearing's high-speed capability, corrosion resistance to sterilization chemicals, and ability to operate without lubrication are critical advantages. The ultra-thin 7 mm width fits tightly into medical handpiece designs.[reference:17]

● Laboratory & Analytical Instruments – High-speed centrifuges, rotary evaporators, analytical precision measurement equipment, and laboratory automation systems requiring chemical resistance and low-maintenance operation in harsh laboratory environments.[reference:18]

● Robotics & Precision Automation – Miniature robotic joints, rotary actuators, and precision positioning stages where space constraints and high rotational accuracy are required. The full ceramic construction provides corrosion resistance in cleanroom and food-grade environments.

● Chemical & Food Processing – Small pumps, mixing equipment, and processing machinery exposed to corrosive media or requiring regular caustic washdown. The ZrO₂ full ceramic bearing offers FDA compliance for food contact and outstanding resistance to most industrial chemicals.[reference:19]

● Aerospace Instrumentation – Gyroscopes, actuator systems, and flight control components requiring lightweight, non-magnetic, and corrosion-resistant bearing solutions that can operate reliably without liquid lubricants over wide temperature ranges.

◆ Technical Data (reference for steel-equivalent; ceramic version specific values available on request)

Note: The technical data table provides reference values based on steel-equivalent 7902 angular contact ball bearings for general sizing estimation. For exact dynamic load rating (Cr), static load rating (C0r), limiting speed, and specific performance data for the ZrO₂ full ceramic version, please consult the manufacturer's technical datasheet or contact supplier. For high-temperature continuous operation above 260°C, a PEEK cage or full-complement (cage-less) design is recommended. Contact angle options typically include 15°, 25°, and 40°.