Page 33 - The Tribology Handbook

A5 Dry rubbing bearings

EFFECT OF ENVIRONMENT

Tmp. Temp.
GPe Pf aboue below Radiation Vacuum Water Oils Abrasives $$Td
matmal
200% - 50’C
Thermoplastics Few Usually Usually Most Often Poor Fair to
+fillers suitable good poor materials poor; good
suitable; watch to
fair ;
PTFE+fillen Fair Very good Very poor avoid finish Usually rubbery Excellent
graphite of good materials
Thermosets+ Some Good Some as mating Some
fillers suitable fair fillers surface best good
Carbon- Very good; Very good Very good; Useless Fair to Good Poor Good,
graphite watch avoid good except
resins resins strong
and acids
metals

PERFORMANCE

Best criterion of performance is a curve of P against V V. ftfrnin
for a specified wear rate. The use of PX V factors can be 10 lo2 10’
misleading. lo2

Curves relate to journal bearings with a wear rate of
25 pm (1 thou.)/100 h-unidirectional load; 12.5 pm (0.5
thou.)/100 h-rotating load 10
Counterface finish 0.2-0.4 pm cla (8-16 pin).
A Thermoplastics
B PTFE
C PTFE +fillers
D Porous bronze + PTFE + Pb
E PTFGglass weave+ thermoset
F Reinforced thermoset+ MoS,
G Thermoset/carbon-graphite +PTFE
0.1

0.01
0.01 0.1 1 10
V, mls

A5.2