Tin and Lead Babbitt Bearing Alloys

Tin- and lead-base babbitt bearing alloys

Babbitt alloys are low-melting bearing materials used as a conformable lining on a stronger bearing shell. The grade, base metal, form and package must match the application and the governing ASTM, SAE, GOST or customer specification.

General characteristics of babbitts

Antifriction alloys on the basis of lead or tin with low melting point which are used for casting between rubbing parts of mobile units were invented by American Isaac Babbitt in 1839.

• Tin B88, B83, B83C (containing Sn, Sb, Cu) were developed by Babbitt
• lead B16, BN, BSb (containing Pb, Sn, Sb, Cu)
• calcium BKA, BK2, BK2SH (containing Pb, Ca, Na).

In Eastern Europe the first two groups of babbitt are the most popular. The composition of tin babbitts according to GOST 1320−74 includes up to 90% Sn, up to 6% Cu and up to 9% Sb. The second group on the basis of lead is regulated by GOST 1209−90.

Advantages of

Babbitts are very ductile at normal temperatures, have a t° of melting — not higher than 440 ° C. They have an extremely low coefficient of friction They remarkably reduces the wear of rubbing parts, increase the efficiency of equipment. The performance of plain bearings is determined by the thickness of the babbitt layer on the steel liner. Babbitts combine high ductility. They accelerate the run-in to the mating surfaces; they are able to retain lubricants but are hard enough to support the shaft. As a result, shaft wear is reduced. These advantages are achieved by the special structure of babbitts: the hard grains are bonded together by a plastic base. The hard particles serve as a base for the shaft to work on and withstand high specific pressures, while the soft base ensures accelerated run-in of the shaft and retains the grease.

Mechanical properties of B83

t°	σB	σT	Density
degrees ° C	N/mm²	N/mm²	g/cm3
20	110−120	80−85	7,38

_σc — Ultimate short-term strength, [MPa]

_σT — yield strength for permanent deformation, [MPa].

Disadvantages

Babbitt alloys are not resistant to shock loads and vibration, which often hinders the operation of moving parts. The low strength allows the use of babbitts only in bearings with a strong housing based on steel or non-ferrous alloys.

Production and use

The most commonly used babbitts are of the following composition:

• 9/10 Sn, 1/10 Cu;
• 8/10 Pb, 1/6 Sb, 1/20 Sn;
• 89% Sn, 7% Sb, 4% Cu.

Mg, Na, Ni, Ca, Cd, arsenic, tellurium are used for alloying babbitts. To improve sliding, the alloy is applied to the bearing liners. Tin babbitts of B88, B83, B83C, SAE11, SAE12, ASTM2 grades have high ductility and excellent sliding properties. Compared to lead babbitts, they are more resistant to corrosion, wear and conduct heat better. Lead babbitts (B16, BN, BSb, BKA, BK2, BK2Sh, SAE13, SAE14, ASTM7, SAE15, ASTM15) are cheaper and more heat resistant.

Area of application

Bearings of rolling mills, compressors, diesel engines, moving units of heavy machinery that do not experience shock loads. Lead-calcium babbitt is used in. motor-axle bearings of electric locomotives and other parts of railway rolling stock.

Grades and supply requirements

Enquiries may include tin-base or lead-base babbitt grades such as B83, B88 and specified ASTM or SAE grades. State the exact standard and grade rather than relying on an approximate cross-reference. If wire or a payout package is required, include the wire diameter, package type and package weight; otherwise state the required ingot, bar or other form.

Related babbitt pages

See B16 and B83 babbitt products, B88 babbitt products and B83 material data.

Request a U.S. quote

Evek LLC serves customers throughout the United States. Typical delivery is 2–3 weeks, subject to grade, form, package and availability.

Contact Evek LLC with the standard, grade, form, dimensions or wire diameter, package weight, quantity and delivery ZIP code.