Structure With SpeedRisk maps simplify Green Belt projects

SIX SIGMA TRAINERS tend to teach

Green Belts (GB) the most advanced

tools in the Six Sigma toolbox and end up

with unfinished projects and exhausted

GBs. The secret is to fulfill the need for

structure in a project without drowning in

details.

One way to do this is to use the cause

and effect matrix in combination with a

risk map. The cause and effect matrix will

show which inputs are most likely to affect

the project goal. Each input is then clari-

fied and prioritized in a risk map.

Clarification Often, there are a number of possible

ideas about how each input can affect the

project goal and each idea can include

several steps. The project team will agree

on one idea at a time and write it down.

Consider, for example, a team analyzing

reasons for length variation. Tool hardness

was one of the inputs graded high in the

cause and effect matrix (see Figure 1).

The team discussed the ways tool hard-

ness can affect the length. One of their

ideas was that sometimes the tool is too

soft, making it wear down too fast, which

leads to the machined part becoming too

long. While clarifying this idea, the team

wrote down all the steps on a reposition-

able note (see Figure 2).

PrioritizationThe project team will put the idea in the

risk map based on the team members’

estimation of how often it happens and

the effect when it does happen. When all

the ideas have been placed in the map,

the team will verify and improve them

one at a time, starting from the upper

right corner.

Risk maps are not rocket science—

most GBs grasp the tool quickly and

adjust it to fit their project needs. This

should be encouraged, since a custom-

made map makes it easier for the team to

agree on where to place each idea.

In the example related to length varia-

tion, a custom-made map was created

(see Figure 3), and the team could simply

ask themselves the question on each axis

and place the repositionable note—de-

pending on the ratings—where judged

most appropriate on the scales.

For the “tool too soft” idea, the team es-

timated that one product ended up being

10 μm too long every hour because of a

soft tool’s premature

wear. Hence, the

note was placed in

the orange section.

The team added five

additional ideas to

the map and, in the

next step, decided to

start with tests and

actions for the two

ideas in the orange

and red sections.

When replac-

ing potential failure mode and effects

analysis (pFMEA) in GB projects with the

simplified risk map, the average number

of ideas analyzed decreased from 22 to

eight. Due to the fast analysis process,

the project goals could be reached in a

shorter period of time.

When introducing the risk map to GBs,

no sales pitch is needed—they embrace it

because it matches the complexity of their

projects. QP

EMMA DANIELSSON is a certified Six Sig-ma Master Black Belt at SKF in Göteborg, Sweden. She has a master’s degree in production and operations management from Chalmers University of Technology in Göteborg. Danielsson holds a Green Belt, Black Belt and Master Black Belt from SKF’s Six Sigma program.

ONE GOOD IDEA BY EMMA DANIELSSON

Six Sigma cause and effect matrix

1 2

Rating of importance to customer 10 5

Key process outputs Length Cost

Process step Process input Total

Tool hardness 9 3 105

Machine settings 3 3 45

Tool placing 3 1 35

Cooling temperature 1 1 15

Cause and effect matrix / FIGURE 1

Steps / FIGURE 2

Tool too soft

Increased tool wear

Length too long

Ever

y h

ou

rEv

ery

day

Ever

y w

eek

1 μm 10 μm 100 μm

How often does it happen?

How large is length deviation

each time?

Length variation map / FIGURE 3

May 2015 • QP 63