Quality Management

Understanding and Creating a Control Plan in Six Sigma

Written byContributing Writer
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Updated onJune 24, 2024

Six Sigma aims to reduce defects to 3.4 per million parts by identifying and improving existing processes. However, simply demonstrating that corrective actions can achieve the Six Sigma rating is insufficient. Ensuring the team has a clear pathway to monitor and evaluate the process after implementing changes is crucial.

Therefore, every Six Sigma implementation is followed by creating, approving, and adopting a control plan.

This article will cover the concept, key components, benefits, and usage of control plans. We will also discuss the importance of choosing an immersive Six Sigma program to gain proficiency in the essential concepts and tools required, including follow-up actions such as the control plan and improved quality policies.

What is a Control Plan in Six Sigma?

A control plan is an all-encompassing record of all the elements required to track, inspect, measure, and control the process after implementing corrective actions. It consists of methods, procedures, inspection techniques, critical metrics, and processes required for these steps.

While it may seem like operator instructions, it is not a replacement for standard operating procedures. It is an additional document that identifies the critical steps that may introduce an error, the dimensions or metrics useful in identifying the mistakes, and the immediate response action plan.

Also Read: Six Sigma Green Belt Exam Tips

Examples of Control Plans

They vary with the industry. The critical manufacturing parameters may not be the same as those for software development. Similarly, there are specific control plans for project management and quality management. Here are some examples to help you understand them better.

Manufacturing of Heat Exchanger Tubes

A factory has received a contract to supply heat exchanger tubes to a customer who assembles the heat exchanger. The customer has stringent requirements for the tubes’ properties and requires the control plan to be approved before the beginning of tube manufacturing.

The tube factory develops the tubes and notes the critical dimensions and special characteristics. It then identifies the possible areas that can fail or introduce errors in the tube. The inspection methods used to measure and detect the flaws are finalized. The information is then tabulated in a control plan. Every step has a number, critical dimensions, measurement methods, response to failure, and person in charge. The steps may also be marked based on how critical they are to the tube’s operation.

Project Cost Management

A control plan works exceedingly well for managing project costs. Suppose the project is the development of gaming software. The project cost control plan includes personnel costs, cloud service costs, testing software costs, user testing costs, etc.

The project manager prepares one, considering all the factors contributing to the project’s expenditure. They then set allowable limits for each factor. It mentions the actions to be taken should the costs approach the limits. The manager also includes the timelines for monitoring the cost. Further, it details the people responsible for each task to escalate issues to the right person.

Also Read: Exploring Lean Process Improvement in Six Sigma

Components of a Typical Control Plan

Now that we know what a control plan is, let’s go through the chief components of a comprehensive one.

Process Controls

Process controls consist of techniques, methodologies, specifications, and criteria for examining, monitoring, and controlling the process. These controls are focused on the process parameters. Any deviation in these parameters can introduce variations in the product and, hence, must be controlled using appropriate measurement and monitoring techniques.

Product Controls

Product controls deal with the dimensions and special characteristics of the product. For example, a control plan for software development includes system requirements, bug identification, response actions, and performance indicators. The motive is to define the metrics that denote a performance variation of the product or are responsible for its efficient functioning.

Inspection and Measurement

Every plan must include information about the techniques used to measure the parameters. For example, the dimensions measured for a hollow aluminum tube will be inner and outer diameters and length. These dimensions may be measured using vernier calipers, go-no-go gauges, and laser contours. So, the control plan must mention these techniques, the dimensions, and the median values they measure.

Sampling

Sampling is crucial to testing the variation between the parts produced in an assembly line. While 100 percent inspection may be required for some parts, other dimensions may not be possible. Hence, selecting the correct sampling rate and time of sampling is crucial. If the product is under development, the control plan may include a note about possible sampling risks.

Reaction Plans

The control plan provides the escalation criteria that decide when a serious deviation needs further investigation. Reaction plans refer to the recommended actions the personnel can take in case of deviations or nonconformities. The typical reaction plans include a physical intervention, containment of faulty parts, investigation, root cause analysis, correction, and prevention. Such a ready reference helps the personnel immediately begin the corrective actions for the typical deviations without waiting several days for the root cause analysis to be completed.

How Does a Control Plan Work?

A control plan completes the Six Sigma implementation process. Here are the key steps to prepare and adopt a comprehensive and effective one.

Establish a cross-functional team consisting of people with varying skills. This will ensure that the group focuses not on just one aspect of the process. It will also ensure that it covers all possible issues from beginning to end.
Evaluate the flowchart for any missing aspects. Prepare a checklist with all the information it must have. Compare the flowchart to the checklist and flag additional requirements. Review it after the modifications and finalize the document.
The checklist must contain the dimensions and special characteristics. Check that all the special characteristics critical for each department are included in the control plan. Prioritize the steps and confirm the required parameters.
Assess the inspection and control methods shortlisted by the various team members. The inspection methods must be sufficient to gather the required data. The control methods must be capable enough to prevent related errors from reoccurring. Also, the methods used for sampling the products should be reviewed.
The control plan must mention the people in charge of monitoring each aspect of the process. Review the capabilities of the personnel in each department and determine the most suitable person for controlling each element.
Set up an error feedback loop and a channel to escalate major issues. Finalize the people responsible for responding to the problems.
Create a draft and note the additional data required to complete the draft. Release the draft copy for review and to check how efficiently it can work in practice.
Modify the plan based on the feedback on the draft and release the final control plan into the system.
Finally, ensure that it has reached all the concerned personnel. Plan for regular audits to ensure it’s implemented as intended.

Also Read: Lean Thinking: Transforming Efficiency in Your Business

Why is a Control Plan Needed?

While a control plan may seem like a repetitive effort and a redundant document, there are some crucial reasons why it is needed. Let us go through some of them.

To provide a clear pathway for the personnel to follow to manage quality
To ascertain the consistency in the quality of the product and process
To ensure appropriate measures are used to control the process and reduce the variation
To develop a sense of responsibility among the personnel toward maintaining quality in every product produced
To enable the team to identify points of improvement and conduct trials for new equipment within the control requirements
To reduce the time required to implement continuous improvement methods
To demonstrate the commitment of the company towards maintaining the quality
To ensure the production of high-quality products and enhance customer satisfaction

Things to Remember Before Developing a Control Plan

A control plan is meant to be understood by people from all management levels. Hence, you must remember certain key points before you develop one.

Simplicity rules. Avoid unnecessary jargon and convoluted sentences. Use simple words, terms, and short phrases.
Ensure that its form and structure are lucid and legible. Providing a long list of tedious instructions will result in some of them being overlooked.
Its length is important. Keep it short so the personnel can quickly identify what to do.
Ensure that every person involved has it ready at hand. Ensure efficient communication channels are established.
Provide options in the plan for steps to be taken in case of emergencies or deviations from the process discussed in the control plan. Mention the people to be contacted for approvals in such cases.
Establish a revision and update process where the on-site people can contact the concerned persons and inform them of the new methods or equipment.

Also Read: What is a Quality Engineer? A Comprehensive Guide to the Profession

Control Plan Template

Multiple templates are available online and customized to the project at hand. You can find manufacturing, quality management, and project management control plans, to name a few. Here’s how a typical control plan for manufacturing looks.

A typical tabular control plan template consists of the following headings—

Title
Revision number, name, and date
Part number and description
Drawing revision number and date
Manufacturing approval
Engineering approval
Step number in the process
Name and description of the step
Safety or criticality rating
Dimensions and tolerance as per specifications
Evaluation technique
Sampling plan
Method to be used for controlling deviation
Reaction plan

Take the Next Step Into the Exciting World of Six Sigma

The control plan proves that the results of the Six Sigma exercise have been successfully integrated into the process. It is a tangible visualization of the control methods that help keep the process consistent. Proficiency in creating control plans is crucial for every quality management professional.

This Six Sigma bootcamp is specially curated to align with IASCC-approved Lean Six Sigma courses. You will be mentored by industry experts and work on Capstone projects sourced from various sectors. The course trains you in key concepts such as DMAIC and Lean methodologies.