How can you use control charts to improve process stability?

1 What are control charts?

Control charts are graphical displays that show how a process variable behaves over time, compared to a central value and upper and lower control limits. The central value is usually the mean or median of the process data, and the control limits are calculated based on the natural variation of the process. Control charts can be used for both continuous and discrete data, depending on the type of chart and the distribution of the data.

2 How do control charts work?

Control charts work by showing you whether your process is in a state of statistical control or not. A process is in statistical control when it only exhibits common cause variation, which is the inherent and random variation that is always present in any process. A process is out of control when it exhibits special cause variation, which is the unusual and assignable variation that is caused by external factors or changes in the process. Special cause variation can indicate problems or opportunities for improvement in your process.

3 How can you use control charts to improve process stability?

Control charts can be used to improve process stability by collecting and organizing process data in a consistent and reliable way. It is important to choose the right type of control chart for your data and calculate the central value and control limits. Points on the control chart should be plotted to look for patterns or trends that indicate out-of-control conditions, such as points beyond the control limits, runs of points on one side of the central value, or cycles or shifts in the data. After investigating and identifying sources of special cause variation, corrective or preventive actions should be taken to eliminate or reduce them. The process performance should be monitored over time, with regular updates to the control chart to see the effects of your actions and check for new sources of variation.

4 What are the benefits of using control charts?

Using control charts can help you achieve several benefits for your quality assurance, such as detecting and preventing defects or errors in your products or services before they reach your customers and reducing waste and rework by minimizing variation and improving consistency in your processes. Additionally, control charts can improve customer satisfaction and loyalty by delivering high-quality products or services that meet or exceed their expectations. Furthermore, control charts can enhance your process knowledge and understanding by identifying the key factors that influence your process outcomes and behavior, while also driving continuous improvement and innovation by finding opportunities to optimize your processes and increase your efficiency and effectiveness.

5 What are some challenges of using control charts?

Using control charts can present some challenges for your quality assurance, such as selecting the appropriate type of control chart and sample size, collecting and analyzing data accurately and in a timely manner, correctly interpreting the control chart to prevent false alarms or overreactions, collaborating with your team and stakeholders to implement and sustain changes, and balancing control and improvement efforts with operational and strategic goals.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?