Page 463 - Design for Six Sigma for Service (Six SIGMA Operational Methods)

Theory of Constraints 421

The heart of the theory of constraints is constraints management. Constraints
management is the systematic approach to identifying, managing, and loosening
up the binding constraints and moving the moneymaking process to a new level.
Constraints management will be discussed in Sec. 12.3.

12.3 Theory of Constraints Implementation Process

The practical implementation process of the theory of constraints is featured
by the following five-step constraints management process:
1. Identify the constraint(s)
2. Decide how to exploit the identified constraint(s)
3. Subordinate everything else in the process to step 2
4. Elevate the system’s constraint(s)
5. Go back to step 1
Now we describe these steps for a constraint.

12.3.1 Identify the Constraint

Identifying the constraint is very essential. The answers to the following
questions will help to pinpoint the constraint:
1. Where is the work backed up? Where are the piles of work waiting?
2. Where do most problems seem to originate?
3. Are there any resources with high utilization? Which one has the
highest resource utilization rate? If it is a constraint, it will never run
out of work and it will always be behind.

The effects of a constraint are always blockage of the resources proceeding
to the constraint resource (resulting in a queue) and starvation of resources
downstream of the constraint resource, as illustrated by Fig. 12.7.

These additional questions should be answered to verify if it is really a con-
straint:
1. If we add another resource, would the output of the facility increase?
2. When this resource is starved or idle, will the entire production plan be
thrown off?

Example 12.3: Bottleneck in a Hospital
Figure 12.8 is a flowchart that shows a simplified version of a patient’s pathway
through the hospital process. It is clear from this that general practitioner (GP)