Page 29 - The Tribology Handbook

Characteristics of rubbing bearing materials

Maximum P loading PV value Cot$cient
Maximum Coejicient of
Msterinl ibfjin2 .niNim' tc%p&m $f expamion I?@&$
Ibf/in2 MN/mZ xft/min x rnis "C friction x 10-6/0c
Carbon/graphite 200-300 1.4-2 4 3000 0.11 350-500 O.lW.25 2.5-5.0 For continuous dry Food and textile machinery
dry operation where contamination by
for continuous operation
P$ 200 Ibf/in2 lubricant inadmissible; fur-
5000 0.18 ( 1.4 MN/m2), naces, conveyors, etc. where
"4 250 ft/min temperature too high for
for short period llfe
(1.25 m/s) conventional lubricants :
..
where bearings are immersed
Carbon/graphite 450-600 3-11 4000 0.145 130-350 0.1Ck0.35 4.2-5.0 Permissible peak load in liquids, e.g. water, acid or
and temperature alkaline solutions, solvents,
for continuous operation dry depend upon metal etc.
impregnant
with metal 6000 0.22
for short period Bearings working in dusty
atmospheres, e.g. coal-mining,
Graphite 10000 70 8000- 0.28-0.35 350600 0.10-0.15 12-13 with Operates satisfactorily foundry plant, steel plant,
impregnated 10 000 iron dry within stated etc.
D metal matrix limits; benefits
P 0.020- considerably ifsmall
cn 0.025 16-20 with quantity oflubricant
grease bronze present, i.e. higher
lubri- matrix PV values
cated
Graphite/ 300 2 -10000 -0.35 250 0.13-0.5 3.5-5.0 Particularly suitable for
thermo- dry operation in sea-water
setting resin or corrosive fluids
Reinforced 5000 35 -10000 -0.35 200 0.1-0.4 25-80 Values depend upon Water-lubricated roll-neck
thermo- dry depend- type ofreinforcement, bearings (esp. hot rolling
setting plastics ing on e.g. cloth, asbestos, mills), marine sterntube and
0.006 plane etc. rudder bearings ; bearings
claimed of rein- subject to atomic radiation
with force- Higher PVvalues when
water ment lubricated
lubri-
cation
Thermo-plastic 1500 10 - 1000 -0.035 100 0.1-0.45 -100 Higher PVvalues accept- Bushes and thrust washers in
material dry able if higher wear automotive, textile and food
without filler rates tolerated. With machinery--linkages where
initial lubrication only, lubrication difficult
PVvalues up to20000
can be imposed