Machinery Lubrication July August 2008

HYDRAULICS AT WORK
BRENDAN CASEY
Why Your Current
Maintenance Strategy
Is Wrong
We live in a skewed world, where nothing is evenly distributed.
For example, 80 percent of the wealth is held by 20
percent of the population. Eighty percent of your firm’s sales
likely come from 20 percent of its customers. And 80 percent of
your breakdowns are due to 20 percent of the causes.
Pareto’s Law
You may recognize this as the 80/20 principle, or Pareto’s
Law, named after the Italian economist Vilfredo Pareto who
first recognized the pattern in 1897. Pareto was studying the
distribution of wealth in England during the 1800s. Perhaps
not surprisingly, he soon discovered that a minority of the
population held the majority of the wealth. But when he
looked further, Pareto also found the distribution of wealth
was both predictably and consistently skewed, regardless of
which nation or time period he analyzed.
“An 80 percent reduction in your
maintenance costs will likely
come from 20 percent of your
maintenance effort.”
Put simply, Pareto’s Law states an almost universal truth
that nothing is uniformly distributed. The comparative split
between any two sets of variables may not be 80/20. It could
be 95/5, 60/40 or any other variation. But it is unlikely to be
50/50, which represents linear or even distribution.
Pareto’s Law has since been validated in many business applications.
Pareto analysis played a significant role in the quality
revolution, with two of its most notable proponents, W.
Edwards Deming and Joseph Juran, applying it to identify the 20
percent of defects causing 80 percent of the quality problems.
In business sales, it is reasonable to expect that if a firm
has five sales people, the top salesperson will bring in 80
percent of the sales – that’s four times the sales of all the
others put together.
Unequal Effort and Return
Understanding Pareto’s Law can help identify points of
leverage. And the more skewed the distribution, the more
powerful the leverage.
In the sales example above, the sales manager’s natural
inclination is usually to invest time and money to improve the
results of her underperforming sales people, whereas the
principle of unequal effort and return represented by Pareto’s
Law means a better outcome (more sales) will be achieved by
shifting these resources to assisting her star performer.
Similarly, in a maintenance environment, if 95 percent of
your breakdowns were due to five percent of the possible
causes, it follows that if you can identify and eliminate this
small percentage of causes, then you will eliminate 95 percent
of your breakdowns.
As you can see, focusing available resources on identifying
a small percentage of causes provides potential for exponential
gains. Little hinges can swing big doors.
80/20 Maintenance Optimization
In the maintenance and reliability field, we already have a
variety of tools designed to help us allocate resources where
they are needed most. The Reliability-Centered Maintenance
framework, which considers the probability and consequences
of failure, is possibly the most well-known of these.
I’m not promoting 80/20 thinking as a replacement for
these tools, but rather as an addition or enhancement to
them. Consider this example:
During a meeting with a new client, I was briefed on the
hydraulic hose maintenance program for its fleet of hydraulic
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