Page 205 - The Six Sigma Project Planner

small amounts of waste upstream that are detected before reaching the
constraint are less damaging to throughput.
4. Elevate the system’s constraint(s). Elevate means “lift the restriction.” This is step
4, not step 2! Often the projects pursued in steps 2 and 3 will eliminate the
constraint. If the constraint continues to exist after performing steps 2 and 3,
look for Six Sigma projects that provide additional resources to the constraint.
These might involve, for example, purchasing additional equipment or hiring
additional workers with a particular skill.

5. If, in the previous steps, a constraint has been broken, go back to step 1. There is a
tendency for thinking to become conditioned to the existence of the constraint.
A kind of mental inertia sets in. If the constraint has been lifted, then you must
rethink the entire process from scratch. Returning to step 1 takes you back to the
beginning of the cycle.

Comparison of TOC and Traditional Approaches
It can be shown that the TOC approach is superior to the traditional TQM approaches to
project selection. For example, consider the data in the table below. If you were to apply
Pareto analysis to scrap rates, you would begin with Six Sigma projects that reduced the
scrap produced by Worker A. In fact, assuming the optimum product mix, Worker A
has about 25% slack time, so the scrap loss can be made up without shutting down
Worker B, who is the constraint. The TOC would suggest first addressing the scrap loss
of Worker B and the downstream processes C and D—the precise opposite of what
Pareto analysis recommends.
Process Scrap Rates
Process Scrap Rate
A 8%
B 3%

C 5%
D 7%

Of course, before making a decision as to which projects to finance, cost/benefit
analyses are still necessary, and the probability of the project succeeding must be
estimated. But by using the TOC, you will at least know where to look first for
opportunities.

Using Constraint Information to Focus Six Sigma Projects
Applying the TOC strategy described above tells us where in the process to focus.
Adding CTx information (see Table 14) can help tell us which type of project to focus
on, i.e., should we focus on quality, cost or schedule projects? Assume that you have
three Six Sigma candidate projects, all focusing on process step B, the constraint. The
area addressed is correct, but which project should you pursue first? Let’s assume that

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