Bearing Selection Guide
Precision Bearing Selection Guide
50+ Years of Engineering Expertise · Authoritative Selection Methodology · Free Technical Consultation
Step 1: Define Operating Conditions
The most critical step in bearing selection—accurately quantifying actual operating parameters. Incorrect load assumptions account for 80% of premature bearing failures.
Key Parameter Checklist
| Parameter | Description | Example |
|---|
| Radial Load (Fr) | Force perpendicular to shaft axis | Motor rotor weight: 500 N |
| Axial Load (Fa) | Force along shaft axis | Gear thrust: 200 N |
| Speed (n) | Maximum continuous operating speed | Spindle: 8,000 RPM |
| Operating Temperature | Actual temperature at bearing location | -20°C to +80°C |
| Target Life (L10) | Rated life at 90% reliability | 20,000 hours |
| Environment | Dust, moisture, chemical exposure | Food processing (requires food-grade grease) |
| Installation Space | Available radial and axial envelope | Bore 20mm, OD ≤ 47mm |
Engineering Tip: When Fa/Fr > 0.3, select a bearing type capable of combined loads (tapered roller, four-point contact, crossed roller). For pure radial loads, deep groove ball bearings are the optimal choice.
Step 2: Select Bearing Type
HCH offers 6 precision bearing series, each with optimal application scenarios:
| Bearing Type | Load Characteristics | Speed Capability | Precision | Typical Applications |
|---|
| Deep Groove Ball | Primarily radial, limited axial | Up to 30,000 RPM | P0/P6/P5 | Motors, pumps, home appliances |
| Tapered Roller | High radial + high axial combined | Medium | P5/P4 | Automotive hubs, gearboxes, construction machinery |
| Crossed Roller | High radial + axial + moment | Medium-low | P5/P4/P2 | Robot joints, harmonic reducers |
| Flexible Thin-Wall | Radial | Medium | P5/P4 | Robot harmonic reducers, lightweight designs |
| Miniature | Light loads | Up to 60,000 RPM | P5/P4 | Drones, medical devices, precision instruments |
| Four-Point Contact | Bi-directional axial + radial | Medium | P5/P4 | Steering systems, industrial slewing rings |
Step 3: Choose Accuracy Grade
| Grade | Runout Tolerance | Application | Cost Factor |
|---|
| P0 (Normal) | ≤ 20 μm | General machinery, conveyors, agriculture | 1× (Baseline) |
| P6 | ≤ 13 μm | Industrial motors, pumps, fans | 1.3× |
| P5 | ≤ 8 μm | Precision motors, machine tool spindles, robotics | 2× |
| P4 | ≤ 5 μm | CNC spindles, harmonic reducers | 3× |
| P2 | ≤ 2.5 μm | Ultra-precision instruments, aerospace | 5×+ |
Step 4: Lubrication Strategy
| Method | Suitable Speed | Temp Range | Pros | Cons |
|---|
| Grease Lubrication | Medium-low (<15,000 RPM) | -30°C to +150°C | Excellent sealing, maintenance-free | Poor heat dissipation |
| Oil Lubrication | High speed (>10,000 RPM) | -50°C to +200°C | Superior cooling, high-speed capable | Requires circulation system |
| Solid Lubrication | Very low speed | -200°C to +400°C | Extreme temperatures, vacuum | Limited life, light loads only |
HCH Recommendation: 90% of industrial applications are best served by grease lubrication. HCH bearings are pre-filled with low-noise NLGI Grade 2 grease as standard. For food-grade, high-temperature, or specialty grease requirements, contact our engineering team.
Step 5: Sealing & Protection
| Seal Type | Suffix | Protection | Friction Torque | Application |
|---|
| Open | — | None | Lowest | Oil-lubricated systems, internal gearbox |
| Metal Shield | ZZ | Dust-proof | Low | Electric motors, clean environments |
| Rubber Seal | 2RS | Water + dust proof | Medium | Appliances, outdoor, humid environments |
| Non-Contact Rubber | 2RZ | Dust-proof | Low | High-speed motors |
Step 6: Installation & Maintenance
| Method | Suitable Size | Key Notes |
|---|
| Press Fit (Mechanical Press) | Small-medium (Bore ≤ 100mm) | Apply force to tight-fit ring only. Never hammer. |
| Hot Mounting | Medium+ (Bore > 80mm) | Heat to 80-100°C. Do not exceed 120°C. |
| Hydraulic Method | Tapered bore bearings | Use with hydraulic nut. |
Maintenance Intervals
- High-speed (>10,000 RPM): Check and re-grease every 500-1,000 hours
- Medium-speed (1,000-10,000 RPM): Maintenance every 2,000-3,000 hours
- Low-speed heavy load: Check lubrication every 500 hours
- Miniature bearings: Typically maintenance-free; replace per equipment manual
Step 7: Common Selection Mistakes
- Ignoring axial loads: The most frequent error—misidentifying combined loads as pure radial, leading to early fatigue spalling.
- Over-specifying precision: Selecting P4 grade for general equipment triples cost with no performance benefit.
- Ignoring grease compatibility: Mixing incompatible greases causes consistency degradation and accelerated bleed-out.
- Incorrect sealing: Using open bearings in humid environments results in rust-related failure within 3 months.
- Improper installation: Hammer mounting damages raceways, causing noise exceedance and drastically reduced life.