Page 357 - The Handbook for Quality Management a Complete Guide to Operational Excellence

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Another real­life example may be helpful. An electromechanical
assembly suddenly began to fail on some farm equipment. An examina­
tion of the fail ures revealed that the wire had been broken inside of the
insulation. However, the assemblies were checked 100 percent for continu­
ity after the wire was installed and the open circuit should’ve been discov­
ered by the test. After a long and difficult investigation, no solution had
been found. However, the problem had gone away and never come back.
About a year later, the quality engineer was at a company party when
a worker approached him. The worker said he knew the answer to the
now infa mous “broken wire mystery,” as it had come to be known. The
problem was caused, he said, when a newly hired probationary employee
was given his two weeks’ notice. The employee decided to get even by
sabotaging the product. He did this by carefully breaking the wire, but not
the insulation, and then pushing the broken sections together so the
assembly would pass the test. However, in the field the break would even­
tually separate, resulting in failure. Later, the quality engineer checked the
manufacturing dates and found that every failed assembly had been made
during the two weeks prior to the sabo teur’s termination date.
In most cases, the security specialist is far better equipped and trained
to deal with this type of error than quality control or engineering person­
nel. In serious cases, criminal charges may be brought as a result of the
sabotage. If the product is being made on a government contract, federal
agencies may be called in. Fortunately, willful errors are extremely rare.
They should be con sidered a possibility only after all other explanations
have been investigated and ruled out.

Failure Mode and Effects Analysis
Failure modes and effects analysis (FMEA), also known as failure modes,
effects, and criticality analysis, is used to determine high­risk functions or
product features based on the impact of a failure and the likelihood that a
failure could occur without detection.
The methodology can be applied to products (design FMEA) or pro­
cesses (process FMEA) as follows (Pyzdek and Keller, 2010):

1. Define the system to be analyzed, including a review of all functions
or processes, the current performance levels for each, and a
definition of failure of each process. The process and its failure
modes were specified in the Define stage, and the current level of
performance documented in the Measure stage; however, during
the Improve stage the process was redefined, so it’s possible the
new process will have different failure modes. The performance
levels will certainly be different, representing the fruits of the
improvement effort.
2. The process map is used to define the steps and functional relation­
ships for the new process.

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