What is white metal bearing material and where is it used in marine engines?

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White metal bearing material is a soft lead-tin alloy (commonly known as Babbitt) used as the bearing lining for crankshaft main bearings and big-end bearings in marine engines. The key idea is that the lining, not the backing, is the wearing surface. Its softness allows the bearing to conform to small irregularities on the crankpin and to embed tiny particles, preventing scoring while maintaining a stable oil-film-lubricated surface. This gives low friction, good load distribution, and sacrificial wear, which is ideal for high-load, high-speed engines found on ships. The backing is usually steel or bronze, while the white metal liner is pressed or cast onto it. Other options refer to hard backing alloys, ceramic coatings, or gear-teeth materials, which do not describe the white-metal lining used on crankshaft bearings.