Control Plans and Sustaining Improvements
Learning Objective
By the end of this lesson, learners will be able to:
- Understand the purpose of a Control Plan.
- Define appropriate monitoring requirements.
- Establish clear responsibility for monitoring and response.
- Define corrective actions for changes in process performance.
- Understand how Control Plans support long-term sustenance.
1. Introduction
A Six Sigma project does not end when an improvement is implemented.
The improved process must continue to perform as intended after the project team moves on. Control Plans provide a structured way to document how improvements will be maintained, including monitoring methods, responsibilities and corrective actions.
The purpose is to make the improved process part of normal process management.
2. Monitoring
A Control Plan defines:
- What is measured.
- How it is measured.
- How often it is monitored.
Monitoring provides ongoing visibility of process performance.
The monitoring approach should be appropriate to the process and the improvement being sustained.
3. Responsibility
A Control Plan should clearly identify who owns monitoring and response.
Responsibility should not remain dependent on the original Six Sigma project team.
The process owner and relevant personnel should understand their responsibilities for:
- Monitoring performance.
- Recognizing abnormal conditions.
- Initiating the defined response.
- Maintaining the required controls.
4. Corrective Action
A Control Plan should define what should happen when performance moves outside the intended condition.
A response plan provides clarity about the action required when a control signal, abnormal result or other defined condition occurs.
This helps prevent uncertainty during process deterioration.
5. Sustaining the Improvement
Sustenance means maintaining the improvement after the project team has completed its work.
For sustained improvement, the organization needs to integrate the new way of working into normal operations.
This may involve:
- Standard Operating Procedures.
- Monitoring requirements.
- Audits.
- Defined responsibilities.
- Corrective-response methods.
The improvement should become part of the organization’s normal process control system.
6. Tools & Techniques
The key tools for this lesson are:
- Control Plan Templates
- SOPs
- Audit Checklists
- Monitoring Plans
- Response Plans
These tools work together to make the improved process clear, controlled and sustainable.
7. Application Example
Packaging-Line Improvement
A factory implements improvements to its packaging line.
A Control Plan is created to define the required monitoring activities, responsibilities and corrective actions.
The Control Plan becomes part of the normal operating system for maintaining the improvement.
8. Case Study
Electronics Manufacturing
An electronics manufacturer reduced soldering defects.
The organization developed a Control Plan covering:
- Inspection frequency.
- Operator training.
- Corrective steps.
The case study reports that defects remained below 1% for over a year.
This illustrates how clearly defined monitoring, responsibility and response mechanisms can support sustained improvement.
9. Black Belt Perspective
A Black Belt should ask:
“What will keep this improvement working after the project is closed?”
The answer should not depend solely on the project team.
The improved process should have:
Defined Monitoring → Clear Responsibility → Defined Response → Sustained Performance
The Control Plan therefore acts as an important bridge between project improvement and normal process ownership.
10. Lesson Practice
- What belongs in a Control Plan?
- What should monitoring define?
- Why must responsibility be explicit?
- What should happen when performance moves outside the intended condition?
- How does a Control Plan support long-term improvement?
- Why should sustenance continue after the Six Sigma project team moves on?
11. Key Learning Points
- Control Plans document how improvements will be maintained.
- Monitoring defines what is measured and how often.
- Responsibility identifies who owns monitoring and response.
- Corrective actions define the response to undesirable process conditions.
- SOPs and audit checklists support standardization and monitoring.
- Sustenance ensures improvements continue after project completion.
- Clear ownership is essential for long-term process performance.
12. Lesson Conclusion
A successful Six Sigma improvement must become part of the normal operating process.
Control Plans, SOPs, monitoring plans, audit checklists and response plans provide the structure needed to maintain the improvement and respond when performance changes.
For the Black Belt, the final question is not only “Did we improve the process?” but also:
“Have we established the controls necessary to sustain the improvement?”