Tin-based Babbitt (#2) is approximately 89% tin with the remainder being antimony and copper. The hardness of this alloy gives excellent load-carrying characteristics.
Lead-based Babbitt (#7) is 75% or more lead. Conventional lead-based Babbitt contains antimony and tin, which greatly increase the strength and hardness of lead. This alloy is fully adequate for lower loads and moderate temperatures.
Some 6 other types, though not generally used, are available to address specific needs. See our Types of Babbit chart for details.
The material creeps or flows slightly under load in the initial stages of running.
The shaft and bearing contours conform with each other to compensate for non-uniform loading present from misalignment.
Under poor lubricating conditions, an alloy of good conformity and run-in behavior is required.
Tin-based Babbitt shows low friction resistance, low wear, good run-in properties and good emergency behavior in the absence of adequate lubrication.
Lead-based Babbitt's good frictional properties and reasonably good corrosion resistance makes them ideal for a wide range of applications
Babbitt has high thermal conductivity which is required to absorb and carry away generated heat. When frictional heat generated in bearings is removed, local hot spot seizures caused by roughness or foreign particles, are prevented.
Babbitt is extremely compatible with shaft materials. It resists seizing or galling under conditions of metal to metal contact at start-up.
One very useful characteristic of Babbitt is its ability to embed or absorb within itself, dirt particles in the lubrication system. This permits particles to be trapped and forced into the Babbitt surface and help prevent damage to the journal or shaft.
Babbitt has good load carrying capacity between 800 PSI and 1500 PSI
Maximum operating temperature for Babbitt is 300º F. In motors 180º F to 190º F is considered running hot. Some turbine applications run as high as 225° F. Many technicians however, will set the alarm at 185º F and trip at 205º F.
Melting temperature for common Babbitt varies from 350º F to 475º F
Special bonding techniques are required to metallurgically bond Babbitt to metal