There was a big hen that climbed up a tree by
eating bull droppings & was proudly perched at
the top of the tree & showing off by crowing
Soon it was spotted by a farmer, who shot the
Moral of the story:
Bullshit might get you to the top, but you
won't be there for long
There is no alternative to – HARD WORK
- but it should be supplemented with a positive
attitude & correct approach
What is Maintenance?
Maintenance describes the management,
control, execution and quality of those
activities which will reasonably ensure that
design levels of availability and performance
of assets are achieved in order to meet
Maintenance is a Risk Control activity
Risk = Consequence x Probability =
Consequence x (Opportunity x Chance)
If maintenance expenditure is viewed as the
premium to be paid for reliability insurance,
then it follows that all maintenance activities
should be directed towards maximum returns
on that investment, i.e. improved reliability.
However in reality this is rarely found to be the
The emphasis is only on returning the machine
to service as quickly as possible without serious
consideration of reliability improvement, even
when the opportunity is presented.
CORE MAINTENANCE ACTIVITIES ARE DEFINED BY DESIGN AND
Additional maintenance activity results from premature equipment
Unexpected failures may incur other costs or losses - such as loss in
production, diversion of planned maintenance resources, loss of
reputation, penalties for late delivery, etc. These are usually very
much greater than the actual repair costs of the failure.
The focus of Maintenance should be to maintain the overall ‘wellbeing’ of the plant – but when the task is just to ‘fix it’ then
Maintenance has failed in its basic mission - through no fault of its
Much has happened in the area of maintenance since the industrial
revolution began - a few hundred years ago, but the changes
especially in the last fifty years have drastically affected the
industrial maintenance systems worldwide.
Prior to the Second World War, machinery was mostly rugged and
relatively slow running having only basic instrumentation and control
systems. The demands of production were not severe and downtime
was not a critical issue and so it was enough to maintain plant and
equipment on a ‘breakdown – repair it’ basis. But those machines
were very reliable.
Even today we can see some machines made in that period, which
have worked continually, are almost as good today as on the day
they were made.
From mid 50's after the world war with the rebuilding of industry,
there developed a much more competitive marketplace with an
increasing intolerance to downtime. The cost of labour increased
leading to more mechanisation and automation. Machinery
became lighter, ran at higher speeds but also wore out more
rapidly and was less reliable, as they were utilised more.
Production then demanded time based maintenance which led to
the development of Planned Preventative Maintenance.
The involved planning for timely plant overhauls at which the
failure rate of a group of similar machines became unacceptable.
This in turn lead to the basic assumption that the older an
equipment gets the more likely it is to fail.
Thus evolved the ‘Bathtub Curve’ concept.
The Bathtub Curve was presumed applicable to All Machines
There were 3 identifiable phases within the Bathtub Curve:
Running In (also known as the Infant Mortality) phase. This recognised
the premature failure of components and was often seen in the first
few days or weeks after overhaul.
Normal Operating Life phase. This showed a relatively constant
probability of failure. Failures within this phase were usually referred
to as Random.
Wear Out phase. There was an increasing probability of component
failure between equal and successive time intervals. Somewhere
within this phase the failure rate would become unacceptable and total
maintenance would be carried out on equipment still in its “normal
This was like carrying out open heart surgery on
This intrusive scheduled maintenance would lead back to
the beginning of a new bathtub curve and the phase of
Infant Mortality with its increased probability of failure.
Effectively, the process of Planned Preventative
Maintenance gave rise to a series of mini-bathtub curves,
each with their initial period of increased high risk
Within Planned Preventative Maintenance the challenge
became one of choosing the best point in the Wear Out
phase at which to perform maintenance - all other factors
With the Bathtub curve often giving disturbing results it
required further investigation.
In the 1960’s with the introduction of the Boeing 747, the aviation
industry questioned the prevalent maintenance strategies and the
long established basic assumption that the older an equipment gets
its more likely to fail.
At that time aviation accident rates were in the order of 60 per
million takeoffs. 20,000 hours flying time required some 2,000,000
man-hours of maintenance.
The bath tub assumption was questioned and the failure process
researched. Various patterns of failure were identified and only three
showed some relationship of increased probability of age related
failure totaling only 11% of the failures. The remaining 89% showed
no age relationship, but a period of constant probability of failure.
This proved that failure is a random event having the potential to
warn of a developing failure through changing levels of some
measurable parameters, indicating a change in condition of the
component, machine or system.
The aviation industry made major changes to its
maintenance practices and the results were
dramatic; maintenance time for 20,000 hours flying
time went from 2,000,000 man-hours down to 66,000
– a 30:1 reduction.
There was a dramatic improvement in safety and
effective reliability. Design and technology
improvements were made and condition based
maintenance techniques became the provider of
information to assist development.
Over the years that followed, industry worldwide also
followed this study and this became the principal
foundation of Reliability Centered Maintenance.
Identifying Potential Machinery Failure
To understand the concept better, let us take a real life
In the above case of a pump & motor, a failure can occur
due to many reasons. Let us firstly identify those reasons
before going further.
Overloading, failure to reach
minimum discharge rates
Increased corrosion, erosion,
Wear and tear (floating ring
seal, plain and roller
bearings, normal corrosion,
Wrong choice of pump
Mistakes in commissioning
(inadequate cleaning of the
system, inadequate venting)
Mistakes during repair
Incorrect start up
Mistakes during cleaning (steam
on plastic, caustic solutions on
The direction of rotation of a
dry pump is not checked.
The oil fill was forgotten.
Having identified the possible ways in which the system may
fail, lets see if it is possible to detect and measure the
Firstly see if past failure history is available. Then use the
information to analyse the cause for the failure.
If the answer is NO then use either Planned Preventative or
Breakdown Maintenance, depending upon the Criticality or
Risk - should the failure event happen.
If the answer is YES, the failure process can be observed,
and the Criticality justifies it, then Condition Based
Maintenance will be applied. If the answer is YES but
Criticality does not justify it, then Planned Preventative or
Breakdown Maintenance will be applied.
Its important to understand that Maintenance and
Downtime are an effect and not a cause. The causes
can be traced back to defects and errors from a
variety of life cycle sources.
These failures can be design errors, material
selection errors, fabrication errors, assembly errors
and even transportation damages that may have
happened to the items before they got to site. When
installed, further causes of future failures arise from
incorrect installation, incorrect site assembly,
improper mounting practices, inadequate
environmental protection and deficient foundations
Manufacturing, installation & commissioning errors
result in early failures in the equipment’s operating
life and are known as ‘infant mortality’ failures.
Errors in a machine that do not appear early in
equipment infant-life will eventually surface
randomly to cause failures sometime during its
These arise from operating errors, repair errors,
abuse, management mistakes and even acts of
The terminology for hidden errors and mistakes is
‘defects’, because they are present in the plant and
equipment with the endless potential to one day
A part properly built and installed, without any errors, will
operate in a machine at its designed level of performance. If
looked after properly, it should ideally, deliver its design
requirements through its operating life.
As a machine is operated any hidden manufacturing or
installation errors in a part will start to make their effects
shown. Not all defects will act at the same time, but some
defects will cause a part to start to fail. Remember that defects
can start failures at anytime.
It is thus essential to devise a systematic method of analysing the
effects and the causes that create or contribute to those effects.
The Fish Bone diagram & FMECA are some such methods.
LETS TRY TO UNDERSTAND THEM
A Cause-and-Effect Diagram is a tool that helps identify, sort and
display possible causes of a specific problem or quality characteristic.
It graphically illustrates the relationship between a given outcome and
all the factors that influence the outcome. This type of diagram is
sometimes called an "Ishikawa diagram"because it was invented by
Kaoru Ishikawa, or a "fishbone diagram" because of the way it looks.
When to use a Cause-And-Effect Diagram?
A Cause-and-Effect Diagram is used when you need to:
Identify the possible root causes, the basic reasons for a specific
effect, problem or condition.
To sort out and relate some of the interactions among the factors
affecting a particular process or effect.
To analyze existing problems so that corrective action can be taken.
A Cause-and-Effect Diagram is a tool that is useful for identifying
and organizing the known or possible causes of quality or the lack
of it. The structure provided by the diagram helps team members
think in a very systematic way.
The benefits of constructing a Cause-and-Effect Diagram are that it
Helps determine the root causes of a problem or quality
characteristic using a structured approach.
Encourages group participation and utilizes group knowledge of
Uses an orderly, easy-to-read format to diagram cause-andeffect
Indicates possible causes of variation in a process.
! Increases knowledge of the process by helping everyone to
learn more about the factors at work and how they relate.
Identifies areas where data should be collected for further study
The fishbone diagram, also known as the Ishikawa diagram after the Japanese
quality management innovator who created it, is a common tool used to help
organizations solve problems by conducting a cause and effect analysis of a
situation in a diagram that looks like a fishbone. The fishbone diagram helps you to
identify the root cause of a problem. It is also possible to identify solutions that may
help solve more than one problem. While carrying out this analysis, you may make
further discoveries that will also help you remove other blocks.
1. Define the characteristics of the problem and make it the “backbone” of the fish.
2. Decide on the main causes of the problem. Divide the causes into the categories
of: Staff, Machine, Material, Method and Environment (or Energy).
3. Assign one “large bone” -- coming off the backbone of the fish -- to each
4. For each main cause, think of an area that contributes to the problem e.g. lack of
training might be a main cause in the Staff category. Write these on the horizontal
lines -- the “middle bones” -- that run out from the large bones.
5. Analyse and define secondary causes and add them as “small bones”:
For each cause, ask why does this happen? If there is another reason, include it on
a branch of the horizontal line for that cause: e.g. why is there lack of training? The
answer maybe may be lack of funding. This should be added to the diagram.
To get a holistic
To get a holistic and logical representation of a
problem broken down into a pictorial format
Need to study a
Need to study a problem/issue to determine
the root cause?
Need to Arrive
At a solution
Need to Arrive at a Solution to any problem
To Enhance a Process
Need to Simplify a process flow
Want to study why a process is not performing
properly or producing the desired results
Repeat this procedure
with each factor
Use an idea-generating technique (e.g.,
brainstorming) to identify the factors within each
category that may be affecting the problem/issue
and/or effect being studied
Repeat this procedure with each factor under the
category to produce sub-factors. Continue asking, "Why
is this happening?" and put additional segments each
factor and subsequently under each sub-factor.
“Continue until "
Continue until you no longer get useful information
as you ask, "Why is that happening?"
Analyze the results of
Analyze the results of the fishbone after team
members agree that an adequate amount of
detail has been provided under each major
“Most Likely Causes",
For those items identified as the "most likely
causes", the team should reach consensus
on listing those items in priority order with the
first item being the most probable" cause.
What is a FMECA?
is an analysis technique which facilitates
the identification of potential design problems
by examining the effects of lower level failures
on the system operation.
These are basically of 2 types:
FMECA - Failure Mode, Effects and Criticality
FMEA - Failure Mode and Effects Analysis
What are the effects
of box failures on
What are the effects
of board failures on
What are the effects
of part failures on
Note: This is a bottoms up example.
Top down examples are possible.
The flashlight below is used by special operations forces
involved in close combat missions during low visibility
conditions. The light is mounted coaxially with the
individual's personal weapon to momentarily illuminate and
positively identify targets before they are engaged. The
exterior casing including the transparent light aperture have
a rugged design and are to be considered immune to failure.
How can it fail?
What is the effect? Note
that Next Higher Effect =
End Effect in this case.
flashlight output dim
no flashlight output
constant flashlight output
no flashlight output
flashlight sometimes will not turn on
flashlight output dim
no flashlight output
flashlight sometimes will not turn on
flashlight output dim
no flashlight output
SEVERITY classifies the degree of injury, property
damage, system damage and loss that could occur
as the worst possible consequence of a failure.
For a FMECA these are typically graded from I to
IV in decreasing severity.
CRITICALITY is a measure of the frequency of
occurrence of an effect.
be based on qualitative judgment or
May be based on failure rate data
Light stuck in the ‘On’condition
Light will not turn on
Can circled items be designed out or mitigated?
(There may be others that need to addressed also.)
FMECAs should begin as early as possible
This allows the analyst to affect the design before it is
finalised. Also if one starts early one can expect to have
to redo portions as the design is modified.
FMECAs take a lot of time to complete.
FMECAs require considerable knowledge of system
operation necessitating extensive discussions with
software/hardware Design Engineering and System
Time should be spent in developing ground rules
with the customer, up front.
If you want your equipment to be truly reliable you must
prevent the introduction of defects and errors at all stages
of equipment life. By getting rid of the defects that
generate failure modes you will reduce your future
The best maintenance strategy to adopt is to not let failure
modes into the equipment from the start. Such strategies
require that you put in place quality management controls
and quality assurance to detect, control and stop the
introduction of errors and defects into the equipment.
Select one failure and identify where defects and errors were first
introduced by employing root cause failure analysis methods.
Use resources towards eliminating the root cause and action a plan
to engineer-out the causes forever. Do not use work procedures to
live with failures from bad engineering design or manufacture. Use
work procedures to direct people’s attention to the right
reliability practices but not to compensate for in-built equipment
defects. If your equipment has engineering defects then engineer
Introduce clear quality, production and engineering standards that
contain Accuracy Controlled checks and tests to prevent the
defects from repeating.
Train and re-train your people to meet the new quality and
Effective mechanisms must be introduced to combat
and defeat the cause of the defects. Unless the causes
are controlled and stopped you will be continually
battling failures. They will never stop because they are
forever being introduced and perpetuated by poor
procedures and practices, poor quality control and poor
Every new piece of equipment, every new part and
even every new person that joins the company will
bring defects and errors with him & one day cause
How catastrophic those failures will be depends on your
internal controls in place to prevent and control them
and your ability to take proper & timely decisions!
Identify the best line of
Reliability is a probability
index, which indicates
that a system will
perform its required
function without failure
under given conditions
for an intended operating
Reliability = MTBF/
(MTBF + MTTR
Look for the relevant data
Aim for absolute clarity
Maintenance technology comprises of technical
knowledge plus experience and their application
in identifying and implementing the best possible
maintenance and repair techniques for all
maintainable items, in line with the
It provides a means to maintain the plant and
equipment in a high state of operating efficiency
and enhance its productivity.
safeguard the investment.
To keep the equipment in good working
To prolong the life of the equipment.
To assure optimum availability.
Types of Maintenance
Breakdown maintenance is
suitable for conditions
Plant capacity exceeds
Standbys are available and
quick switching is possible
Process is obsolete and more
modern equipment is under
For non critical equipment.
Preventive maintenance is
different from Breakdown
It is a systematic
wherein the condition of
the plant is constantly
systematic inspection and
preventive action is taken
to reduce the incidence of
Fundamentals of PM
of plant and
equipment to discover
Upkeep of equipment
to remove or repair
such conditions while
they are still in a
Advantages of P.M
Effective use of manpower
and material to attain
greater efficiency in plant
Planning of maintenance
work and optimum
inventory of spares and
Possible to synchronize
the maintenance program
so that there is least
interruption to continuous
operation and production.
IF YOU CAN’T SEE IT, YOU
CAN’T FIX IT
So use: High pressure
Anti-Rust & Grease
“To make smooth or
slippery with oil,
grease or other
matter to overcome
any procedure that reduces
friction between two moving
Any material that reduces
The main function of a
lubricant is to separate two
moving surfaces and make
their relative movement
Lubricants achieve this by
substituting low fluid
friction in place of high
Prevent or Minimise FRICTION by:
Providing a film to separate interactive surfaces
Coating the rubbing surfaces with a protective film
By reducing or removing excess heat
By inhibiting the corrosive processes caused by air and
By flushing dirt particles away from lubricated
Mineral oils carry out these functions effectively
Always exists where there is sliding contact
between two surfaces
Always consumes power
Always produces heat
Is independent of contact area and sliding
Is dependent on surface roughness and
Represented by COEFFICIENT OF FRICTION
The two well known laws of physics that
govern sliding friction are:
1. The friction between two solid bodies is
independent of the area of contact.
2.The friction between two solid surfaces
is proportional to the load by one surface
COEFFICIENT OF FRICTION
µ = F/W
where F = frictional force opposing motion
And W = the load
Friction x 2
Friction x 3
Direction of motion
sharp edge scrapes away oil
- BOUNDARY LUBRICATION
Direction of motion
bevelled edge rides over oil
- FLUID FILM LUBRICATION
WHAT IS VISCOSITY?
The viscosity of a liquid is the measure of its
resistance to flow.
Under the same conditions, a liquid with a low viscosity
will flow more readily than a liquid with a high
viscosity. It is most commonly expressed in terms of
Centistokes or SAE numbering.
Viscosity is the single most important property of a
It is a major factor in the formation of a lubricating
film and, therefore, determines the load carrying
capacity of the lubricant, i.e. it indicates performance.
Why need maintenance performance
indicators in the Mining Industry?
Mining is a capital & labor intensive
Maintenance costs range between
20-50% of production cost.
Hence maintenance is an integral
part of it’s long -term profitability
Maintenance can add value through
equipment reliability and availability
In order to optimize maintenance
functions it thus becomes
imperative to have maintenance
performance indicators in place.
In mining various indicators can be
used for measuring maintenance
However, many managers still advocate
that ‘performance measurement is not
effective nor beneficial in mining
Some maintenance managers still
believe in the ‘let it work till it
breaks’ syndrome commonly called breakdown maintenance.
But in order to optimize maintenance
performance one has to be different
and have the DESIRE to go ahead –
like this Socrates anecdote
A young man asked Socrates the secret to success. Socrates told the
young man to meet him near the river the next morning. They met.
Socrates asked the young man to walk with him in the river. When
the water got up to their neck, Socrates suddenly ducked the young
man into the water. The boy struggled to get out but Socrates was
strong and kept him there until the boy started turning blue.
Socrates then pulled his head out of the water and the first thing
the young man did was to gasp and take a deep breath. Socrates
asked, 'What did you want the most when you were there?" The boy
replied, "Air." Socrates said, "That is the secret to success. When
you want success as badly as you wanted the air, then you will get
There is no other secret.
A burning desire is the starting point of all
Just like a small fire cannot give much heat, a weak
desire cannot produce great results.