Page 206 - The Six Sigma Project Planner

we learn that one project will primarily improve quality, another cost, and another
schedule.
Table 14. Throughput Priority of CTx Projects That Affect the Constraint

Project Discussion
Type
CTQ Any unit produced by the constraint is especially valuable because, if it is
lost as scrap, additional constraint time must be used to replace it or
rework it. Since constraint time determines throughput (net profit of the
entire system), the loss far exceeds what appears on scrap and rework
reports. CTQ projects at the constraint are the highest priority.
CTS CTS projects can reduce the time it takes the constraint to produce a unit,
which means that the constraint can produce more units. This directly
impacts throughput. CTS projects at the constraint are the highest priority.

CTC Since the constraint determines throughput, the cost of the constraint
going down is the lost throughput of the entire system. This makes the
cost of constraint downtime extremely high. The cost of operating the
constraint is usually miniscule by comparison. Also, CTC projects often
have an adverse impact on quality or schedule. Thus, CTC projects at the
constraint are low priority.

Does this new information help? Definitely! Take a look at Table 14 to see how this
information can be used. Projects in the same priority group are ranked according to
their impact on throughput.
The same thought process can be applied to process steps before and after the
constraint. The results are shown in Table 15.
Table 15. Project Throughput Priority vs. Project Focus

Focus of Six Sigma Project
Before the At the After the

CTx: Constraint Constraint Constraint
Characteristic Quality (CTQ)
addressed is critical
Cost (CTC)
to…
Schedule (CTS)

Low throughput priority.
Moderate throughput priority.

High throughput priority.
Note that Table 15 assumes that projects before the constraint do not result in problems
at the constraint. Remember: impact should always be measured in terms of
throughput. If a process upstream from the constraint has an adverse impact on

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