Six Sigma Green Belt Certification Practice Exam

A process capability study has been performed on a manufacturing process. It is found that the process spread is the same as the specification spread. What action should be taken?

1. Reduce variability

2. Change the specifications

3. Center the process

4. Take no action

The correct answer is: Center the process

The correct action is to center the process. In a scenario where the process spread is equal to the specification spread, the process is operating at its full capacity, but it may not be positioned ideally within the specification limits. Centering the process involves adjusting the mean of the process so that it sits equidistant from both specification limits, which can enhance the likelihood of producing products that meet specifications consistently. When the process is centered, it minimizes the risk of producing items that fall outside the specification limits due to natural variability. This is particularly important because while the spread being equal to the specifications suggests that the process is capable, without centering, there is still a potential for non-conformance if the process mean drifts too close to either specification limit. Reducing variability may not be necessary since the process spread is already equal to the specification spread. Changing specifications could lead to unnecessary alterations to the established standards, which might not be the best course of action since the existing specifications potentially align well with the process capability. Taking no action would not be advisable as it could result in non-conforming outcomes despite the current capability. Therefore, centering the process is the most effective course of action to enhance performance and reduce the risk of defects.