Advantages of Babbitt Bearings and Sound Babbitt Foundry Practices

Originally invented in the early 19th century, Babbitt metal has since come to be associated with the softest type of metal bearing material. The type of Babbitt foundry work produced today is not quite the same type of metal originally produced by Isaac Babbitt, as those formulations were kept as trade secrets. Today babbitt metals are classified by ASTM International and are divided into two main categories. First is tin babbitts whose most common alloy is ASTM B23, Grade 2.  The second category is lead babbitt alloys, most popularly used being ASTM B23, Grade 7.  The former is used most often because of the restrictions on the use of lead.

The selection of journal and thrust bearing materials is based on five principal factors – (1) compatibility, (2) embeddability and conformability, (3) corrosion resistance, (4) compressive and fatigue strength and (5) cost and availability.  Compared to popular bronze bearings, aluminum bearings and zinc alloy bearings, babbitt bearings outperforms these other bearing materials in the first three factors.  Combining a thin layer of babbitt on a steel backing markedly improves its fatigue resistance and load carrying capacity.  Although more labor intense, the addition of the low cost backing reduces the overall bearing cost, making the babbitt bearing a top performer in all the desirable bearing traits.

When compared to ball and roller bearings the most significant advantages of Babbitt bearings are the gradual and predictable wear they offer. While rolling element bearings are commonly associated with catastrophic failure that is not the case with Babbitt bearings. For this reason, Babbitt-lined bearings are commonly used in high-speed compressors, large motors, generators, turbines, and internal combustion engines.

Wheeler Industries follows strict babbitt foundry procedures using centrifugal casting methods to insure high strength bonds between the babbitted bearing surface and the hard backing material.  Following practices prescribed in DOD-STD-2183 and MIL-STD-271F, our ultrasonic testing of the bearing surfaces confirms the integrity of the metallurgical bond between the lining and backing.  At Wheeling Industries, we are able to manufacture a wide array of designs. With almost a century of experience, we can help with the design, testing and manufacturing of almost any type of bearing.