Page 192 - Lean six sigma demystified

Chapter 5 Redu C ing d efe C t S with Six Sigm a 171

Adjusting the motor is 55% of total motor service and lube is the next 30%
(85% total). Now we have something to analyze!

A problem well stated is a problem half solved.
—Charles Franklin Kettering (1876–1958)

Once we have narrowed the problem down to a small enough piece, we can write
a problem statement about one or more big bars on the Pareto chart. The big bars in
the lower-level Pareto charts can be turned into problem statements to fill the head
of your fishbone diagram. These will serve as the basis for identifying root causes. We
also need to set a target for improvement.
Problem Statement: During 2004, adjust-
ments accounted for 55% of all motor ser-
vice calls, which is higher than desired and
caused customer dissatisfaction and a loss
of $60 per service call.
Now let’s pull back and look at the
service row (Figs. 5-22 and 5-23). FIGURE 5-22 • Services by type data.

n = 61 Total service and warranty calls by type
61 100%
90%
53.375
89%
80%
45.75 72% 70%
Number of calls 22.875 25 41% 60%
38.125
50%
30.5
40%
15.25 19 10 30%
20%
7
7.625 10%
0 0%
Install Adjust Lube Replace
Type
FIGURE 5-23 • Total service calls by type Pareto chart.

As you can see, installation is 41% of the
total followed by adjustments. These two
are 72% of the total. Next, I’ll drill down by
looking at the installation column (Figs. 5-24
and 5-25). FIGURE 5-24 • Installation part repairs Pareto chart.