A company makes a kind of fine mesh netting used for filtering purposes in various industries. There is always a demand to make the mesh finer, but the finer the mesh is made, the weaker it becomes, and the more it tends to rip in manufacturing, shipping and use. A team was assigned the task of determining whether changes could be made in manufacturing the mesh so as to improve strength without adding major new equipment or processing procedures that would increase cost greatly.
The first thing the team did was to assemble all interested parties in the company at a brainstorming
session. They began by making a process flow diagram (Figure 
) of the mesh making
process
in order to have in detail before them what was (supposed to be, at least) the way the process
worked.
At the same session, they developed an Ishikawa diagram (Figure ) giving a complete list of possible
factors. In developing the Ishikawa diagram, the team used the 5 M s + E as categories:
Man, Machine, Methods, Materials, Measurement, and Environment.
The Ishikawa diagram, also called a fishbone or cause and effect diagram,
is a
visual aid for initially identifying possible causes of observed phenomena.
In the example,
the main arrow or trunk
points
to the phenomenon being studied (High Strength Mesh).
The branches pointing directly to the trunk
are the relevant causes of variation among the 5 M s + E . The smaller branches
list possible causes of variation identified as affecting the
major causes of variation, and so forth.
These two diagrams focused the team's thinking on possible causes of variation in the process, and served as a starting point for finding ways to improve the manufacturing process.