Bearing Materials — Best Choice for Light Loads and High Speeds Which material is most suitable for bearings subjected to light loads (and often higher speeds), prioritizing embeddability and conformability?

Introduction / Context:
Plain (journal) bearings require materials with specific tribological properties: low friction, good embeddability (ability to absorb dirt), conformability, and compatibility with the shaft. For lightly loaded, high-speed service, soft bearing alloys are often preferred.

Given Data / Assumptions:

• Application emphasizes low unit pressure and reliable lubrication.
• Desire to protect the shaft from scoring in case of contamination or boundary lubrication.
• Conventional hydrodynamic journal bearings considered.

Concept / Approach:
White metal (babbitt) alloys, typically Sn–Sb–Cu (tin-based) or Pb–Sb–Sn (lead-based), are soft and conformable, provide good embeddability for debris, and run safely at high speed with thin oil films. They are widely used as bearing linings or shells for light to moderate loads.

Step-by-Step Solution:
Establish performance needs: low friction, tolerance to misalignment/debris.Compare materials: babbitt excels in embeddability and conformability versus bronzes and hard alloys.Select white metal (babbitt) for light-load bearings.

Verification / Alternative check:
Standard design texts specify babbitt-lined bearings for turbines, small motors, and pumps under appropriate load-speed regimes.

Why Other Options Are Wrong:

• Phosphor bronze/silicon bronze: stronger but less embeddable; used for higher loads.
• Monel metal: corrosion-resistant Ni–Cu alloy, not a preferred bearing lining.
• Tool steel: far too hard for plain bearing linings.

Common Pitfalls:
Choosing a very strong alloy for light loads; strength is less important than tribological compatibility in such cases.

Final Answer:
white metal (babbitt)