Guide: Control Plan
- Last Updated: June 11, 2023
In business it is not uncommon for processes and outputs from processes to be out of control and need action to be taken to address them. This is where Control Plans become extremely useful. Control plans have been developed to support lean Six Sigma process and quality management systems in measuring critical-to-quality (CTQ) measures of processes and their outputs to ensure they remain in control with regular data collection and clear actions to be taken to address issues if they arise.
Control plans are mostly popularized and used within the manufacturing sector. However, they can be useful for a range of processes that output variables that can be measured and controlled.
Table of Contents
What is a Control Plan?
A Control Plan in its basic form is a document that outlines the process, steps and actions needed to manage, control, and ensure the quality of a process or product. Developed from the principles of Lean Six Sigma, the tool is used to many industries, such as manufacturing, logistics, automotive, and aerospace.
Control plans may vary slightly from business to business as teams and management tweak them to suit local business needs. However, the Control Plan typically consists of elements such as process input variables, output variables, control points (limits), what measurements are to be taken, and actions to be taken if a deviation occurs.
Below you can see a good example of how a control plan may look. You can also download this control plan from our template section.
A control plan is usually a tool you will use towards the end of an improvement project, such as in the Control phase of the DMAIC methodology, and continues to serve as a “living document,” which means it is continually reviewed and updated as the process evolves or new data becomes available.
How to Create a Control Plan
Creating a Control Plan is an important process that involves several steps. The guide below will clearly explain each step to guide you through creating a robust and effective Control Plan.
Step 1: Identify the Process
The first step in creating a control plan is to identify a process that you are looking to control. This should be a process that is critical to the quality of your product or service and would have a significant impact on customer satisfaction or operational efficiency if it were to go wrong. Therefore, lend them to a key candidate of a process to control
It is important to have a clear understanding of the flow of the process, including the inputs and outputs and all the steps involved. It can be useful to use a tool such as a flowchart to map out the process to ensure you fully understand all the elements and variables of the process.
Step 2: List CTQs (Critical to Quality Characteristics)
Once the process has been identified, the next step in the process is to identify the CTQ characteristics. These are the key attributes or features of the product or service that need to be controlled to ensure quality.
The best way to identify what the CTQs are is to understand the customer requirements, such as product specifications.
For example, let’s say a business manufactures brake pads, and the CTQ is the thickness tolerance of the brake pads; this might be ±0.5mm.
Step 3: Select Measurement Methods
Once you have listed all the CTQs that you want to control, decide how you will measure these characteristics. The method that you decide on should be accurate, reliable, and repeatable and follow the principles of Attribute Agreement Analysis (AAA). The measurement method should consider what tools, instruments, or techniques will be used. Additionally, it is important to define the frequency with which the measurement is taken and what the acceptable limits or tolerances are for each CTQ.
Step 4: Determine Control Methods
Now that you know what CTQs you want to control and the methods used to measure them you need to determine the methods of control. Control methods are the strategies, tools or techniques used to ensure that the process stays within the defined limits or customer spec limits.
Popular tools and techniques used to control processes and variables include Statistical Process Control (SPC) charts, Mistake Proofing (Poka Yoke) or Standard Operating Procedures (SOP) / Standard Work Instructions (SWI), which control method you use will depend on the type of process and CTQ identified.
Step 5: Develop Action Plans
If in the event a process or variable goes out of control it is important to take action to address and correct the process and bring it back under control. To do this action plans should be developed as part of the control plan. These action plans define what steps need to be taken to bring the process back within its acceptable limits.
Like any good action plan it needs make it clear what action needs to be taken and who is responsible for taking that action.
Step 6: Train the Team
Now that you have developed a control plan its important to ensure that in the event it is needed, it is used. Therefore, you should clearly communicate what the CTQs are, what the operators need to do to measure the process and clarify what actions need to be taken by whom if a process goes out of control.
Training is key to the success of the control plan being followed.
Step 7: Implement and Monitor
Now that you have developed and trained out the plan, the next step is to officially implement it. This involves putting all the required measures and controls into place. If special tools like calipers or software’s are needed to take measurements, ensure they have what they need. The process then needs to be continuously monitored to ensure the process remains within the stated control limits. Data should then be analyzed at regular intervals to detect and trends or deviations in the process outputs.
Step 8: Review and Update
Finally Step 8, it is important to remember that the control plan is a living document that should be reviewed and updated regularly as the process or CTQs change. Regular reviews will ensure the Control Plan remains effective and relevant.
By following this process you should be able to develop a robust Control Plan that will help you control your process and ensure quality and drive continuous improvement of the process.
Conclusion
Implementing a Control Plan is beneficial for controlling the quality and performance of processes and preventing defects or quality issues. From identifying the process to training your team, each step is geared towards ensuring that your business operations are as seamless as possible. The goal is not just to maintain current performance levels but to set the stage for continuous improvement.
As we’ve outlined in this guide, creating and implementing a Control Plan is a detailed process involving multiple steps, each is important and builds on the previous step. You should also remember, a Control Plan is a living document must be regularly monitored and updated to its sustain success.
References
- Westgard, J.O., 2003. Internal quality control: planning and implementation strategies. Annals of clinical biochemistry, 40(6), pp.593-611.
- Mehrasa, M., Pouresmaeil, E., Jørgensen, B.N. and Catalão, J.P., 2015. A control plan for the stable operation of microgrids during grid-connected and islanded modes. Electric Power Systems Research, 129, pp.10-22.
Q: What is a control plan?
A: A control plan is a documented framework that outlines the methods, procedures, and actions necessary to maintain process control and ensure consistent and acceptable outcomes. It helps identify critical control points, measurement methods, control limits, and corrective actions to monitor and manage process performance effectively.
Q: Why is a control plan important?
A: A control plan is important because it helps organizations maintain process stability, minimize process variations, and ensure consistent product or service quality. It provides a systematic approach to monitor, control, and improve processes, leading to reduced defects, improved customer satisfaction, and increased operational efficiency.
Q: How does a control plan fit into the DMAIC methodology?
A: A control plan is a key component of the Control phase in the DMAIC (Define, Measure, Analyze, Improve, Control) methodology. In this phase, the control plan is developed to sustain the improvements made during the earlier phases. It helps ensure that the process remains in control, deviations are promptly addressed, and continuous improvement efforts are sustained.
Q: What are critical control points?
A: Critical control points are specific stages or activities within a process where variations can significantly impact the quality or outcome. These points need to be closely monitored and controlled to prevent defects or deviations from the desired target. Examples include temperature control, pressure control, or specific steps in a manufacturing process.
Q: How are control limits determined?
A: Control limits are determined based on historical data, customer specifications, or statistical analysis. Historical data provides insights into the process performance, while customer specifications define the acceptable range for product quality. Statistical techniques, such as process capability analysis, can help determine control limits based on the process’s inherent variation and the desired level of performance.
Q: What is the role of corrective actions in a control plan?
A: Corrective actions are specified in a control plan to address deviations from control limits or target values. These actions provide a systematic approach to identify and resolve the root causes of variations, ensuring that the process is brought back into control. Corrective actions may involve adjusting process parameters, modifying procedures, retraining employees, or conducting equipment maintenance, among other steps.
Q: Who is responsible for implementing a control plan?
A: Responsibility for implementing a control plan typically falls on the process owner or a designated team responsible for process management and improvement. These individuals or teams are accountable for monitoring the process, collecting data, analyzing it for deviations, and implementing corrective actions when necessary.
Q: How often should a control plan be reviewed and updated?
A: A control plan should be reviewed and updated regularly to ensure its effectiveness and alignment with changing process requirements. It is recommended to review the control plan during regular process performance reviews or when significant changes occur in the process or customer requirements. This helps to adapt the control plan to evolving conditions and continuously improve its efficacy.
Author
Daniel Croft
Daniel Croft is a seasoned continuous improvement manager with a Black Belt in Lean Six Sigma. With over 10 years of real-world application experience across diverse sectors, Daniel has a passion for optimizing processes and fostering a culture of efficiency. He's not just a practitioner but also an avid learner, constantly seeking to expand his knowledge. Outside of his professional life, Daniel has a keen Investing, statistics and knowledge-sharing, which led him to create the website learnleansigma.com, a platform dedicated to Lean Six Sigma and process improvement insights.
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