Page 24 - The Tribology Handbook

Plain bearing materials A4

Requirements and characteristics of lubricated plain bearing materials

Physical Signijcance of property in Characteristics of widely used materials
serum
Property White metals Copper-base allqs Aluminium-base allovs
-
Fatigue To sustain imposed Adequate for many Wide range of strength Similar to copper-base
strength dynamic loadings at applications, but falls available by selection alloys by appropriate
operating temperature rapidly with rise of of composition selection of
temperature composition
Compressive To support uni- As above As above As above
strength directional loading
without extrusion or
dimensional change

Embedd- To tolerate and embed Excellent- unequalled Inferior to white metals. Inferior to white metals.
ability foreign matter in by any other bearing Softer weaker alloys Alloys with high
lubricant, so materials with low melting content of low melting
minimising journal point constituent, e.g. point constituent, e.g.
wear lead ; superior to tin or cadmium;
harder stronger alloys superior in these
Conform- To tolerate some mis- in this category. properties to copper-
ability alignment or journal These properties can base alloys of
deflection under be enhanced by equivalent strength.
load provision of overlay, Overlays may be
e.g. lead-tin or provided in appropriate
Cornpati- To tolerate momentary lead-indium, on cases to enhance
bility boundary lubrication bearing surface where these properties
or metal-to-]metal appropriate
contact without seizure

Corrosion To resist attack by acidic Tin-base white metals Lead constituent, if Good. No evidence of
resistance oil oxidation products excellent in absence of present, susceptible to attack of aluminium-
or water or coolant sea-water. Lead-base attack. Resistance rich matrix even by
in lubricant white metals attacked enhanced by lead-tin alkaline high-additive
by acidic products or lead-tin-copper oils
overlay
Bh ysical properties, forms available, and applications of some white metal bearing allo ys

Physical properties
Type of bearing Melting Hardness Coejicient Forms auailable Applications
range, "C Hu at 20°C of
x 10"6/"C
~~ ~~
Tin-base white 239-312 -23-25 -23 Lining of thin-walled steel- Crankshaft bearings of ic
metal IS0 4381 backed half-bearings, engines and reciprocating
Sn Sb8 Cu4 split bushes and thrust compressors within fatigue
washers; lining of bronze- range; FHP motor bushes;
tin 89% backed components, gas turbine bearings (cool
antimony 7.5% unsplit bushes end) ; camshaft bushes;
copper 3,.574 general lubricated
applications
Tin-base white 239-340 -27-32 -23 Lining of medium and Crankshaft and cross-head
metal IS0 4381 thick-walled half-bearings bearings of medium and
Sn Sb8 Cu4 Cd and bushes; lining of large diesel engines within
direct-lined housings and fatigue range; marine
tin 87% connecting rods gearbox bearings ; large
antimony 8% plant and machinery
copper 4% bearings; turbine bearings
cadmium 1%
Lead-base white 245-260 -26 -28 'Solid' die-castings ; lining of General plant and machinery
metal IS0 4381 steel, cast iron, and bearings operating at
Pb SblO Sn6 bronze components lower loads and
temperatures
tin 6 Yo
antimony 10%
copper I%
lead 83%

Note: for the sake of brevity the above table lists only two tin-base and one lead-base white metal. For other white metals and appiications
refer to IS0 4381 and bearing suppliers.
A4.1