Mechanical Technology may 2015

Mechanical Technology — May 2015

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Proactive maintenance, lubrication and contamination management

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Mario on maintenance:

he first article in this series dis-

cussed the evolution of mainte-

nance strategies as we see them

today, broadly described under

the terms passive, reactive, preventative,

predictive and proactive. It was shown

that an optimised asset management

system would invariably incorporate all of

these strategies, in a mix to suit the type

and criticality of the asset as it pertains

to the owner. It sounds perfectly logical,

but how to go about it practically? A good

place to start is to categorise assets in

terms of the strategy to be adopted. Just

like planning, it needs some time out to

take in the big picture.

This is beneficial for many reasons,

but the following are important in the

context of proactive maintenance:

• It will bring focus to the assets that

really matter.

• At a later stage, when considering

predictive maintenance, it minimises

the investment needed.

Let’s consider the kind of thinking that

goes into categorising assets by mainte-

nance strategy.

Any asset or component that is low

cost, quick and easy to repair or replace

and has no significant production, safety,

environmental, consequential or reputa-

tional risk associated with its failure is

eligible for passive maintenance.

Passive

maintenance

requires no further con-

sideration in respect of the categorised

asset, as there is nothing to do. It only

requires a decision to identify which

assets are appropriate choices for this

maintenance strategy.

Reactive maintenance

is a good

option when there are no significant

production, safety, environmental, conse-

quential or reputational risks associated

with failure, but repair or replacement is

a moderate cost and/or not straightfor-

ward. In this case, foresight is required to

prepare for the eventuality, so that when

failure does occur (as it will), there is a

known process to repair or replace the

faulty asset in as short a time frame as

the situation demands.

This may mean ensuring availability

of internal resources and establishing a

relationship with a preferred service pro-

vider so as to affect repair or replacement

without undue delay in a cost effective

Progressive strategies

in proactive maintenance

In this issue’s maintenance column, Mario Kuisis describes the importance of categorising

assets into appropriate maintenance strategies and to progressively introduce new

approaches as maintenance maturity grows.

An SDT ultrasound detector is being used here to determine the optimum lubrication level for a bearing.

This exemplifies how predictive maintenance tools and techniques can be added to a preventative mainte-

nance strategy to further failure.

way with appropriate specifications and

quality processes in place. The internal

resources could include trained per-

sonnel, strategic spares, special tools,

handling equipment, etc. Typically, no

operational costs are incurred, other than

possibly the holding of strategic spares.

Preventative maintenance

becomes

attractive when the consequences of fail-

ure justify it. This can be due to high cost

and complexity of repair or replacement

and/or when significant loss of production

is a likely result. Safety, environmental,

reputational and other consequential

risks associated with failure are also

increasingly important. If these outweigh

the costs of conducting reactive mainte-

nance, then it is an appropriate strategy

for the asset in question.

The important point is to think about

these factors and make the best business

decision, but there are no hard and fast

rules and the process also needs repeat-

ing every few years as circumstances

change. The extent and frequency of

preventative maintenance can of course

also be adapted. Usually, the OEM will

provide all the information necessary for

internal preventative maintenance or for

outsourcing to third parties. For some

specialised equipment, the OEM may be

engaged to advantage.

If one were to stop here, life for the

maintenance practitioner would be rela-

tively easy. Unfortunately, it is no longer

good enough for most industrial plants

and utilities because the unplanned

outages that would result thrust to the

heart of competitiveness, quality of

supply and reputation. Often safety and

the environment are also at play. In the

end, business sustainability itself can

be threatened. Hence, a more proactive

approach is required.

The next step in the chain of progres-

sion is, therefore, to consider which as-

sets would benefit from

predictive main-

tenance

. This is a crucial step in many

ways and more complex than it would

appear. But what do we mean by predic-

tive maintenance? In this discussion the