Components and Materials of Bearings

Bearings are critical components in machinery that reduce friction between moving parts, allowing for smoother motion and increased efficiency. The materials used in bearings are chosen based on the specific requirements of the application, such as load capacity, speed, temperature resistance, and corrosion resistance. Below is a detailed overview of the components and materials commonly used in bearings.

Types of Bearings

1. Ball Bearings

   • Application Example: Light thrust and radial load applications like computer fans.

2. Roller Bearings

   • Application Example: Heavy radial load applications such as conveyor belt rollers.

3. Ball Thrust Bearings

   • Application Example: Light radial load and low-speed applications like barstools.

4. Roller Thrust Bearings

   • Application Example: Large thrust load applications such as gear sets.

5. Tapered Roller Bearings

   • Application Example: Large thrust and large radial load applications like car hubs.

Metallic Materials Used in Bearings

1. Chrome Steel (SAE 52100)

   • Commonly used for roller, ball, and tapered roller bearings.
   • Excellent wear resistance with a Rockwell hardness of about 64 HRC.
   • Functional at temperatures up to 120°C; can go up to 220°C with heat treatment.
   • Prone to corrosion due to low chromium content.

2. Stainless Steel (AISI 440C)

   • Higher chromium content (up to 18%) provides superior corrosion resistance compared to SAE 52100.
   • Can function at temperatures as high as 250°C.
   • Lower hardness and overall load-carrying capacity; higher production cost.

3. Carbon Steel

   • Also known as ‘commercial grade,’ contains up to 2.1% carbon by weight.
   • Stronger with higher carbon content but less ductile and lower melting point.
   • Suitable for low-load, low-speed applications like rolling draws, locks, bikes, roller skates, and shopping carts.

Non-Metallic Materials Used in Bearings

1. Thermoplastics (e.g., igus® xiros® Plastic Ball Bearings)

   • Available in different grades:
     • A500: Extreme chemical resistance; temperatures up to 302°F (150°C).
     • B180: High wear resistance; temperatures up to 176°F (80°C).
     • C160: Chemical-exposed applications; temperatures up to 176°F (80°C).

2. Ceramics

   • Used for their high-temperature stability and corrosion resistance.

3. Composites

   • Often used where lightweight or specific mechanical properties are required.

Typical Application Areas of Bearing Materials

• Industrial machinery
• Automotive components
• Aerospace systems
• Consumer electronics
• Medical devices

Factors Considered in Selecting Bearing Materials

1. Load Capacity: The material must withstand the operational loads without deforming or failing.
2. Speed: High-speed applications require materials that can handle high rotational speeds without excessive wear or heat generation.
3. Temperature Resistance: Applications involving high or fluctuating temperatures need materials that maintain their properties under thermal stress.
4. Corrosion Resistance: For environments exposed to moisture or chemicals, materials with high corrosion resistance are essential.
5. Cost: The material choice often balances performance requirements with budget constraints.