Why is the liner of a journal bearing composed of babbitt?

The liner of a journal bearing is composed of babbitt primarily to reduce friction. Babbitt, which is a soft metal alloy typically made of tin, lead, and copper, has excellent properties that contribute to minimizing friction between the bearing surface and the journal (the rotating part). Its soft nature allows it to conform and adapt to any surface irregularities, providing a smoother interface. This adaptability reduces wear and tear, ensuring that the bearing operates efficiently while maintaining a low coefficient of friction.

Choosing babbitt for journal bearings is a strategic decision in engineering design because, in addition to reducing friction, it also aids in cushioning the impact loads. This can prolong the life of both the bearing and the journal, ensuring reliable operation in machinery.

Other options like increasing rigidity, enhancing conductivity, or improving wear resistance do not specifically highlight the primary advantage of using babbitt in journal bearings, which is its exceptional capacity to minimize friction and maintain efficient performance in demanding operating conditions.