Bearings - Babbitt Bearings

Explain Babbitt metal

Babbitt metal

This article is licensed under theGNU Free Documentation License.It uses material from the Wikipedia article "Babbitt metal" (click for full Wikipedia text)

'Babbitt metal ', also called white metal, is an alloy used to provide the bearing surface in a plain bearing. It was invented in 1839 by Isaac Babbitt in Taunton, Massachusetts, Massachusetts, United States. The term is used today to describe a series of alloys used as a bearing metal. Babbit metal is characterized by its resistance to Gall (failure mode). Common compositions for Babbitt alloys:

90% tin 10% copper

89% tin 7% antimony 4% copper

80% lead 15% antimony 5% tin Originally used as a casting in situ bulk bearing material, it is now more commonly used as a thin surface layer in a complex, multi metal structure. Babbitt metal is soft and easily damaged, and seems at first sight an unlikely candidate for a Bearing (mechanical) surface, but this appearance is deceptive. The structure of the alloy is made up of small hard crystals dispersed in a matrix of softer alloy. As the bearing wears the harder crystal is exposed, with the matrix eroding somewhat to provide a path for the lubricant between the high spots that provide the actual bearing surface.

Traditional babbitt bearings

In the traditional style of white metal bearing, a cast iron pillow block is assembled as a loose fit around the shaft, with the shaft in approximately its final position. The inner face of the cast iron pillow block is often drilled to form a key to locate the bearing metal as it is cast into place. The ends of the bearing are packed with clay and molten white metal poured into the cavity around the shaft, initially half filling the pillow block. The bearing is stripped, and the white metal trimmed back to the top surface of the pillow block. Hardened white metal is hardness enough to be cut with a knife or sharp chisel. A steel shim is inserted to protect the face of the lower bearing and to space the cap of the pillow block away from the shaft. After resealing the ends with clay, more white metal is then poured to fill the cap of the pillow block through the hole in the top of the pillow block cap that will eventually be a lubrication hole. The two halves of the bearing are then split at the shim, the lubricant holes cleared of white metal and any grease ways cut into the surface of the new bearing. The shaft is smeared with Prussian blue and rotated in the bearing. When the bearing is disassembled the blue fills the hollows and is rubbed off the high spots. The high spots are scraped down, and the process repeated, until a uniform and evenly distributed pattern of blue shows when the shaft is removed. The bearing is then cleaned and lubricated, and shimmed up such that the shaft is held firmly but not binding in the bearing. The bearing is then "run in" by being run heavily lubricated at low load and revolution, completing the process of exposing the hard bearing surface. After final adjustment of the shimming, a very reliable and high force capability bearing results. Before the wide availability of cheap electric motors, power was distributed through factories from a central engine via line shaft running in hundreds of bearings of this form. The expression a "run bearing" also derives from this style of bearing, since failure of lubrication will lead to heat build up due to friction in the bearing, eventually leading to the white metal liquifying and literally running out of the pillow block.

Modern Babbitt bearings

In more modern practice, the crankshaft and connecting rod big end bearings in a modern automobile internal combustion engine have bearings made of a replaceable steel shell, keyed to the bearing caps. The inner surface of the steel shell is plated with a coating of bronze which is in turn coated with a thin layer of Babbitt metal as the bearing surface. The process of laying down this layer of white metal is known is Babbitting.

Alternative Bearings

In many applications rolling-element bearings such as ball bearings, or roller bearings have replaced Babbitt bearings. Though such bearings can offer a lower coefficient of friction than plain bearings, their key advantage is that they can operate reliably without a continuous pressurised supply of lubricant. Ball and roller bearings can also be used in designs and configurations which are required to carry radial as well as axial thrusts.

This article is licensed under the GNU Free Documentation License.It uses material from the Wikipedia article "Babbitt metal" (click for full Wikipedia text) Close explanation

Hide

The Bearings QED site has been constructed to provide information on bearings, services and data. The site breaks bearings down over a number of categories for your convenience. The current category is Babbitt Bearings .



	American Babbitt Bearing - Welcome Babbitt bearing repair and new manufacture. ASTM certified alloy. 24 hour service.
	American Babbitt Inc .com - Customer Satisfaction Assured! Specializing in the manufacture and repair of babbitt bearings and labyrinth seals for all types of high speed rotating equipment.
	Babbitt Bearings Syracuse, NY, plant produces and repairs Babbitt precision OEM bearings for high speed rotating equipment: compressors, turbines, electrical motors, pumps, ...
	bearings at BearingsHQFind bearnigs suppliers for air, babbitt ... Database for manufacturers of industrial ball bearings including roller, angular, pillow block and hydrodynamic bearings.
	Canadian Babbitt Bearings Inc.
	Cincinnati Babbitt - Babbitt Bearing Repair and Machine Services CBI is a non-oem Babbitt bearing repair and new manufacture facility. Specializes in turbine, generator and motor bearing repair and new manufacture.
	Home-Babbitt Bearing Repair Provides Babbitt bearing repair and refurbishment services.
	Odessa Babbitt Bearing Company - Odessa, TX - Houston, TX ... Manufacturer of babbitt bearings, labyrith seals, and bushings of bronze and aluminium. Recondition any size of marine or power generation bearing.
	PME Babbit Bearings and Babbit Bearing Repair Repair and manufacturing of Babbitt bearings and Babbitted components for turbines, generators, fans, and motors.
	The Babbitt Pot Specializes in rebabbitting and boring babbitted bearings and engine rebuilding of early internal combustion engines. Includes service information and contact ...
	Victory White Metal Company solder, babbitt, and anodes Suppliers of solder, babbitts and anodes.
	Web Page Manufactures and relines white metal babbitt bearings.