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Minitab LLC

Six Sigma

SPC Helps Medical Device Manufacturer Maintain Quality

Minitab software performed the data analysis for product improvement

Published: Wednesday, December 1, 2010 - 15:02

ResMed is a global manufacturer of medical devices. The company’s products help people with sleep-disordered breathing (SDB) and other respiratory disorders. Characterized by the interruption of normal breathing patterns during sleep, an estimated 18 million people in the United States suffer from SDB symptoms.

Dedicated to discovering innovative solutions, ResMed invests 7 percent of its net revenues in research and product development. The company has more than 3,000 patents and design registrations granted or pending. In its ongoing quest for continuous improvement, ResMed trusts Minitab Statistical Software to perform the data analysis necessary to make the best decisions for product improvement, and uses Minitab macros to execute real-time statistical process control.

The challenge

ResMed wanted to refine the manufacturing process for its best-selling masks and machines as part of its continuing efforts to improve product quality. It hoped that this initiative would reveal how to maximize the efficiency of its manufacturing efforts, raise the visibility and boost understanding of the process, identify changes in production that could improve product quality, and showcase the benefits of statistical process control to others in the company. To accomplish this, ResMed set out, through a pilot project, to measure continuous parameters such as flow, gain, and pressure, as well as attribute data such as error codes.

How Minitab helped

The idea for using Minitab macros came to ResMed after using the software’s open database connectivity to query test data—efforts that just happened to coincide with a Minitab “Tips and Tricks” workshop, where ResMed staff learned about using macros. The solution they designed is simple:

• Test data from the production line is stored in a database.
• Microsoft Scheduler schedules Minitab to run every 30 minutes with a start-up file that launches a macro.
• Minitab queries the data, creates the control charts, and saves them to a designated directory.
• ResMed’s SharePoint site retrieves the graphics and displays them for review.
• The SharePoint site automatically refreshes data every 10 minutes.

Throughout the pilot, ResMed used Minitab individual control charts to monitor daily production, X-bar charts to monitor weekly production, and P charts to monitor yields (i.e., number of good units over total units made). RersMed also used Minitab to create real-time Pareto charts that display the previous day’s codes to line operators.

ResMed used Minitab individual control charts to monitor daily production, X-bar charts to monitor weekly production, and P charts to monitor yields.




ResMed reaped several benefits from this quality improvement effort. The company can now quickly and easily demonstrate that its processes are in statistical control. It gained greater understanding of test parameters and results, and the manufacturing department can proactively make changes in production so that the company does not end up with product that might not meet ResMed’s strict quality standards.

During the pilot, for example, the manufacturing team detected a downward trend involving a particular tool cavity. A preliminary investigation showed that the cavity had become eccentric. Although the process still made product that was within specification, over time it could have produced nonconforming product. To avoid this issue, the tool cavity was replaced, and the process was improved.

In addition, instituting the new process will eliminate a legacy paper-based system freeing up workers to address other matters. Looking ahead, the company anticipates long-term benefits in improved product quality and fewer customer complaints.

From its start with Minitab’s basic statistics, control charts, and process capability tools to its current use of macros in the pilot for real-time monitoring of production processes, ResMed’s reliance on Minitab continues to pay dividends in terms of quality and efficiency.


About The Author

Minitab LLC’s picture

Minitab LLC

Minitab Inc. develops statistical analysis and process improvement software for academic and commercial users. Minitab Statistical Software, a data analysis tool for businesses, has been used to implement virtually every major Six Sigma quality improvement initiative, and to teach statistics in more than 4,000 colleges and universities worldwide. Quality Companion is used to plan and execute Six Sigma projects. Use the subscription-based online learning course, Quality Trainer, to learn or refresh your knowledge and to access quality statistics expertise anytime. Interactive lessons based on real problems make concepts easy to retain.