Step 1: Determine Bearing Type
Three types are widely used in aerospace:
Deep‑groove slim thin ball bearings: For general airborne equipment and precision mechanisms
Four‑point contact slim thin ball bearings (X‑type): Can bear radial and bidirectional axial loads simultaneously; the most common choice for aerospace
Angular‑contact slim thin ball bearings: For high‑speed spindles and servo mechanisms
Priority recommendation: Four‑point contact slim thin ball bearings for light weight, compact size and high load capacity.
Step 2: Select Precision Grade (Non‑negotiable for aerospace)
General airborne equipment: ABEC‑5 / ISO Class 5 (P5)
High‑speed instruments, UAVs, inertial navigation systems: ABEC‑7 / ISO Class 4 (P4)
High‑end aero‑engines and guidance systems: ABEC‑9 / ISO Class 2 (P2)
Required supporting specifications:
Raceway Finish: Surface roughness Ra ≤ 0.1–0.2 μm
Race Runout: Strict control of micrometer‑level radial runout
Step 3: Choose Cage Type (Aerospace‑only designs; stamped steel cages are prohibited)
Snap‑Over Phenolic Cage: One‑piece rivet‑free design, lightweight, stable for high‑speed light‑load applications
Toroid Separator: Integral ring separator for balls, superior shock resistance and stability; standard for four‑point contact bearings
Avoid stamped steel cages and nylon cages due to poor temperature resistance and short service life.
Step 4: Select Sealing Type (Aerospace‑grade only)
Preferred: 2 PTFE Seals, double‑sided
Low friction, resistant to −70 °C low temperature, compatible with aerospace fluids, anti‑aging
Open type: For external oil lubrication
Not recommended: Standard rubber 2RS seals (poor temperature resistance, prone to failure)
Step 5: Select Lubricant (Strictly matched to working conditions)
1. Maintenance‑free long‑life service, wide temperature range (−73 °C ~ +121 °C):
Mobil Grease 28 (MIL‑G‑81322), standard aerospace grease
2. Ultra‑low‑temperature high‑speed oil lubrication:
Tribolube‑L3 Light Oil (−57 °C)
3. Fire‑resistant high‑temperature airborne applications:
Brayco Micronic 882 Oil (MIL‑PRF‑83282D)
Sealed bearings: Mobil Grease 28 preferred; Open high‑speed bearings: Light Oil preferred.
Step 6: Material & Special Functions
Standard material: High‑purity AISI 52100 aerospace‑grade bearing steel
Non‑magnetic equipment (navigation / magnetic sensors): Non‑magnetic stainless steel (440C non‑magnetic grade)
Servo / variable‑frequency motors: Add VL0241 outer‑ring insulating coating to prevent electrical corrosion
Environmental requirements: Salt spray resistance, compatibility with aerospace hydraulic oil and fuel, moisture resistance
Step 7: Size, Load & Weight Reduction (Core aerospace requirement)
Choose the thinnest cross‑section possible under load constraints to minimize weight
Four‑point contact design bears both radial and axial loads, reducing the number of bearings for further weight saving
Verify DN value, radial/axial load, shock load and operating temperature