Page 353 - The Handbook for Quality Management a Complete Guide to Operational Excellence

340 C o n t i n u o u s I m p r o v e m e n t I m p r o v e / D e s i g n S t a g e 341

For example, if we can collect the money from customers as their
burgers are being cooked, then the total cycle time is reduced.
3. Reduce time for remaining internal steps. There are some internal
steps that cannot be done while the process is operational. We now
want to concentrate on reducing the time required to complete
those steps that require the process to be delayed. For example,
since the burgers cannot be cooked until we know what the
customer wants to order, we will try to reduce the time it takes to
place the customer order.
4. Eliminate adjustments. Adjustments, as discussed in the Analyze
stage, can be reduced through effective process control. Designed
experiments may be used to understand the causes of process
variation that precede the adjustment.

Define and Mitigate Failure Modes

Once the process flow is established, it can be evaluated for its failure
modes. Understanding process failure modes allows us to define mitiga­
tion strategies to minimize the impact or occurrence of failures. These
mitigation strategies may result in new process steps, optimal process set­
tings, or process control strategies to prevent failure. In some cases, in
which failure cannot be economically prevented, a strategy can be devel­
oped to minimize the occurrence of the failure and contain the damage.
The cause­and­effect diagrams discussed in the Analyze stage are
again useful for brainstorming the potential causes of failures. This brain­
storming activity will provide necessary input to process decision program
charts and failure modes and effects analysis.

Process Decision Program Chart
The process decision program chart (PDPC) is a technique to prepare con­
tingency plans. It is a simplified version of the reliability engineering
methods of failure mode, effects, and criticality analysis (FMECA) and
fault tree analysis (discussed later in this chapter). PDPC seeks to describe
specific actions to be taken to prevent the problems from occurring, and to
mitigate the impact of the problems if they do occur. An enhancement to
classical PDPC is to assign subjective probabilities to the various prob­
lems and to use these to help assign priorities. Figure. 16.1 shows a PDPC.
Preventing Failures
Many failures occur due to human error, particularly in service processes.
While the failure may result from human error, it does not necessarily imply
that process or system­level solutions could not prevent its occurrence. In
other words, focusing on individuals’ performance (or lack of performance)
will not realize an improvement.

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