Page 26 - The Tribology Handbook

Plain bearing materials A4

Physical properties, forms available. and applications of some aluminium-base alloy
bearing materials

Physical properties
Type of bearing Melting Hardness Coefiient Fom availabls Afplicatfom
range, "C H. at 20°C of expansion
x 10-61"c
Duralumin-type -550-650 -80-150 -22-24 Cast or wrought machined Bushes, slides, etc., for slow
material, no depend- components speed heavily loaded
free low ing on applications, e.g. small
me1 ting-poin t com- ends of medium and large
constituents position diesel engines; general
and heat machinery bushes,
treatment etc.
Low tin aluminium Matrix -45-60 -24 Cast or rolled machined Unsplit bushes for small-ends,
alloy -650 Components. As lining of rockers, linkages, gearboxes.
IS0 4383 steel-backed components. Crankshaft half-bearings
AI Sn6 Cu Usually overlay plated for diesel engines and
for crankshaft bearing linings of thin- and
tin 6% Tin applications medium-walled steel-
copper 1% eutectic backed crankshaft bearings
nickel 1% -230 for heavily loaded diesels
aluminium and compressors; also as
remainder
linings of steel-backed split
bushes.
Aluminium Matrix -55 -22 As lining of thin-walled Heavily loaded diesel engine
silicon-cadmium -650 half-bearings, split bushes crankshaft bearings ; small-
alloy and thrust washers. end, gearbox, rocker
IS0 4383 Usually overlay plated bushes, etc.
A! Si4 Cd for crankshaft applications
silicon 4% Cadmium1
cadmium 1% -320
aluminium
remainder
Aluminium tin Matrix 55-65 -24 As lining of Heavily loaded crankshaft
silicon alloy -650 thin-walled bearings for high-speed
IS0 4383 half-bearings, petrol and diesel engines.
tin 10 or 12% Tin split bushes Used without an overlay
silicon 4% eutectic and thrust
copper B or 2% -230 washers.
aluminium Used without
remainder an overlay

High tin aluminium Matrix -40 -24 As lining of thin- and Moderately loaded crankshaft
alloy -650 medium-walled half- bearings for high-speed
IS0 4383 bearings, split bushes petrol and diesel engines.
AI Si20 Cil and thrust washers. Camshaft gearbox and
Usually used without an linkage bushes; thrust
tin 20% Tin overlay washers
copper I%, eutectic
aluminium -230
remainder
Overlay plating

Fumtiom of an overlay Typical overlay compositions
1 To provide bearing surface with good frictional pro- 1 10-12~o tin, remainder lead
perties, Le. compatibility 2 IOo% tin, 2% copper, remainder lead
2 To confer some degree of embeddability Tin and copper may be higher for increased corrosion
resistance.
3 To improve load distribution Where the maximum corrosion resistance is required with
4 To protect lead in lead-containing interlayer materials lead-tin-copper overlays or copper-lead a nickel
(e.g. copper-lead, lead bronze) from corrosion interlayer 0.001 mm thick is used beneath the overlay
3 5-8% indium, remainder lead
Thicknesii of overlay
0.017 rnm (0.0007 in) to 0.040 mm (0.0015 in) depending 4 2040% tin, remainder aluminium applied by vapour
upon bearing 1o:ading and type and size of bearing deposition (sputter) on aluminium alloy substrates
A43