Page 34 - The Tribology Handbook
P. 34
Dry rubbing bearings A5
WEAR
‘Running-in’ wear 0-A is very dependent upon counter-
face roughness. Approximately, wear rate a (cla rough-
ness)
‘Steady-state’ wear A-B depends on (i) mechanical
properties of the material and its ability to (ii) smooth the
counterface surface and/or (iii) transfer a thin film ofdebris.
In general, the steady-state wear rate, depth/unit time =
KPV (u.b.c.d.e). X is a material constant incorporating
(i), (ii), and (izi) above. Wear-rate correction factors
N N ING - IN a,b,c,d,e, depend on the operating conditions as shown
below.
0 TIME
Approxiniate values of wear-rate correction factors
rotating load
I-
continuous motion
El
u, Geometrical factor unidirectional load
[oscillatory motion
metal housing, thin shell, intermittent operation
0
b, Heat dissipation factor metal housing, continuous operation
. non-metallic housing, continuous operation
El
G, Temperature factor 100°C
El
2ooc
i 200°C
PTFE-base carbon-graphite, thermosets
stainless steels, chrome plate
d, Counterface factor steels
soft, non-ferrous metals (cu alloys, A1 alloys)
-0.1-0.2 pm cla (4-8 pin)
0.2-0.4 pm cla (8-16 pin) E
e, Surface finish factor
10.4-0.8 pm cla (16-32 pin)
Note: Factors do not apply to metal-solid lubricant composites.
A5.3
