Babbitt, also called Babbitt metal or bearing metal, is any of several alloys used for the bearing surface in a plain bearing.
Babbitt metal is soft and easily damaged, which suggests that it might be unsuitable for a bearing surface.
As the bearing wears, the softer metal erodes somewhat, which creates paths for lubricant between the hard high spots that provide
the actual bearing surface. When tin is used as the softer metal, friction causes the tin to melt and function as a lubricant,
which protects the
bearing from wear when other lubricants are absent.