On Wed, 3 Feb 1999, Power British Performance Parts, Inc. wrote:
>> The silver-gray material is usually some alloy of lead, tin, and other more
>"exotic"
>> metals. It is very soft, and is designed to allow particulates to "bed"
>into it
>> rather than chew up the crank journal.
>And Andy Asked:
>Is that was is referred to as "Indium"?
Indium is an element, symbol In. It is soft, ductile, metal, probably not
suitable
for bearings, I think. You are possibly thinking of the term "Babbitt metal",
very commonly used to describe the white metal in bearings...
>From an old "Materials Handbook":
-------------------------
"Almost any commercial metal can be used for machinery bearings if required,
but certain
metals and alloys are particularly suitable for bearings, chiefly because of
the fact that
a proportion of hard crystals is formed in a background, or matrix, of softer
metal, supporting
the shaft and permitting the free circulation of the lubricant. In the soft
metals, these crystals
are fo\rmed largely by the antimony. See Babbitt and Antimonial lead. In the
bronzes, the crystals
consist of a chemical compound of copper and tin, leaving the excess copper as
the matrix."
<snip>
"The choice of a bearing metal is usually a compromise of hardness, compressive
strength, coefficient
of friction, and degree of lubrication."
<snip>
"Babbitt Metal. The original name for tin-antimony-copper white alloys used for
machinery bearings,
but the term now applies to almost any white bearing alloy with either tin or
lead base. The original
babbitt, named after the inventor, was made by melting together 4 parts by
weight of copper, 12 of
tin, and 8 of antimony, and then adding 12 parts of tin after fusion. ...This
alloy melts at 462 F.
It has a Brinell hardness of 35 at 70F, and 15 at 212F."
--------------------
There is (or was) an SAE standard for Babbitt metal for connecting rod bearings.
Regards,
Ray
-------------------------------------
Ray W. James, P.E., Ph.D.
Civil Engineering Department
Texas A&M University
College Station, TX 77843
Phone (409)845-7436; Fax (409)845-3410
E-mail: r-james@tamu.edu
Date: 2/3/99 Time: 5:53:16 PM
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