No. 4, 1998 - Tribology in Industry

3. TRIBOLOGIC,{L ENERGY LOSSES
Tiibological processes, thus, inevitatrly cause direct energy
and material losses, and with time this becomes apparent
e$ worsening of the system's flnctionaiiry and faiiure.
In order to decrease, prevent and elirninate negative
c()usequences of friction auci wear, differenr maintenance
activities are being undertaken. On the other side,
tribologically shorten working life of technical systerns,
containeci in various equipment, manufacturing means,
transportation means, etc, as a consequence has a need
for new investments. Considering that, the negative consequcnces
of tribological processes (tribological losses)
can be irlentified on different levels (Figure 3).
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L_:":r tso r "o Gr cnr.
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Figura 3. Gbbal .correquencas of tibological processcs
The most glol--aiiy considered, they can be of direct and
indireci character (Figure 4) with respect to tribological
processes [2].
Direct losses are iinnrediate energy ioss due to friction,
arid matenal loss of contact elernents due to wear, as well
irs losses relatecl to maintenarrce. It combines diiferent
Teftiary
TRIBOLOGlCAL
LOSSES/SAVINGS
ecti"",ities, like monitoring of changes in conditions of
both cornponents and systems, diagnostic of their
functions, as wcli as definition and undertaking of concrete
actions of cieaning, lubrications. regeneration, repair,
elemenis replacement, etc., what is, however, related
to production of necessary means for maintenance
and spare parts.
Direct energy losses due to friction are marked as primary
direct losses. These losses are the easiest to spot, and
in superficial approach to the problem they are assumed
as equal to total losses of tribological nature. The truth
is that in total lost e nertry, in technical systems functioning,
the large share belongs to losses due to friction.
thus, fricticn is the important cause of low efficiency
ratio of technical systems.
The secondary direct losses are mainly relateC to necessity
of producing and replacement of the worn criiical
elements of the tribomechanical systems, and lubrication
in orcler to decrease intensity of friction and wear. With
that it shoulci be kept in mind that the requirement for
simultiineous decrease of friction and wear is not always
present, what is compatible. Sometimes is present the
requirement for increase clf friction and simultaneous
decrease of wear (wheel/track, car tires/road, brakes,
frictional transmissions, etc.). N{aterial machining for
replacing the worn elements nssume set of technologies
in which the energr is consunred, what can also be quantified
energetically.
The tertiary direct losses, namely savings, are mainly
related to material for manufacturing the worn elements.
Amount of losses/savings is proportional to enerry equivalent
of material and price. Every loss/saving on the
primarl level of lowering the friction and wear most
frequently res,,rlts in even higher effects on the secondary
and teriiary level.
Same as prirnary and secondary losses, the tertiary losses
also have dimension of energy. Namely, the metal machining
procedures, as rvell as the material itself that is used
for manufar:turing the triboelements, have their own
enertry equivalent [2].
Indirect losscslsavings come as a consequence of direct
ones of any kind. Losses due to delays (prirnary indirect
losses) are economicaily very irnportant, but they do not
have the energy dinrension. The secondary indirect savings
of tribologic:rl nature reflect on the capital investments
plan, and lot only through money, but also
through energy and rnaterial. Here we think of investments
that are consequence of tribologically decreased
working life of equiprnent, as well as the need for increasing
the efficiency.
Figure 4. Gicbal clatsificatk:rt of ttibological losscshavings
150
Tribolog' irt irulustry, Volunte 20, No. 4, 1998.