05-12-2012, 06:33 PM
Investigation of tribological and mechanical properties of metal bearings
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Abstract.
Copper, aluminum and tin–lead based alloys are widely used as journal bearing materials in tribological
applications. Bronze and brass are widely used as journal bearing materials for copper based alloys.
Zamacs find applications as journal bearing materials for zinc based alloys, while duralumines are chosen as
journal bearing materials for aluminum based alloys. In addition, white metals are widely used as journal
bearing materials for tin–lead based alloys. These alloys ensure properties expected from journal bearings. In
this study, tribological and mechanical properties of these journal bearings manufactured by metals were
investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min
for a total of 150 min by using radial journal bearing wear test rig.
Introduction
In the past few years, wood, iron and skin have been used
as journal bearing materials. Later, brass, bronze and white
metal have also found some applications. Currently, in
addition to these bearing materials, aluminum and zinc
based materials are used as journal bearing materials. With
technological improvements, self-lubricated sintered bearings
and plastic materials are used where continuous lubricating
is impossible. Therefore, it is essential that the bearing
material be chosen depending upon area of application.
Wear resistance is one of the most important properties
that journal bearings should possess. There are several
studies and investigations dealing with wear resistance
improvements of these materials (Eyre 1991; Schatt and
Wieters 1997; Enomoto and Yamamoto 1998; Ünlü 2004).
Copper based materials are widely used as bearing materials
because they have high thermal and electrical conductivity,
self-lubrication property, good corrosion and
wear resistance (Schmidt and Schmidt 1993; Paulo 2000).
The effect of tin on wear in copper based materials is
important. Copper based tin bronzes are used as bearing
materials to have a high wear resistance (Prasad 1997).
Friction and wear properties of these materials can be
improved by adding tin (Backensto 1990). Tin bronze
(90% Cu and 10% Sn) is the most suitable bearing material
under corrosive conditions, at high temperatures and
high loads (Pratt 1973).
Radial journal bearing wear test rig
Bearing materials in journal bearings were generally
selected from materials which had lower wear strength
than the shaft material, thereby lowering the wearing of
the shaft significantly. For this reason, journal bearing
wear test apparatus were designed to examine the wearing
of bearing materials. In this study, a special bearing
wear test apparatus has been designed to examine the
wearing behaviour of bearing material and the shaft
together. Therefore, it is possible to investigate different
bearing and shaft materials and the effects of heat treatments
on these materials. Such a mechanism provides
wear of bearings rather than using standard methods as
this is more appropriate (Atik et al 2001).
Conclusions
We conclude that journal bearings manufactured from
metal based materials may be effectively used in the
industry due to better tribological and mechanical properties.
In this study, tribological and mechanical properties
of journal bearings manufactured by metals were investigated.
The following conclusions can be drawn:
(I) Post wear values of surface roughness decreased in
CuSn10 and CuZn30 and increased in other bearings.
(II) The highest friction coefficient and bearing temperature
occurred in CuSn10 and CuZn30 bearings, whereas
the lowest friction coefficient and bearing weight loss
occurred in other ZnAl, AlCuMg2 and SnPbCuSb bearings.
The highest journal weight loss occurred at CuZn30
and AlCuMg2 bearings.