How to Perform Measurement Systems Analysis

Why Should You Attend:

While calibration, which is often delegated to an accredited external laboratory, determines whether a gage or instrument is accurate, MSA is often performed in-house on actual parts to quantify the gage's precision. This presentation will show how to perform MSA, and check and report the results.

Areas Covered in the Webinar:

• Understand the difference between calibration (accuracy) and precision (repeatability and reproducibility)
• Components of gage capability
• Repeatability (gage dependence)
• Reproducibility (inspector dependence)
• Effects of gage variation on outgoing quality, estimates of the process performance index, and statistical process control (SPC)
• Procedure for a gage reproducibility and repeatability study
• Sampling requirements and procedure
• Calculation of repeatability and reproducibility
• Assessment of the results
• Remedies for non-capable gages
• Replication of measurements
• Guard banding (moving the acceptance limits inside the specification limits to protect the customer from borderline nonconforming parts)

Who Will Benefit:

This webinar will provide valuable assistance to personnel in all manufacturing companies. Employees who will benefit include:

• Manufacturing Engineers
• Quality Engineers
• Technicians

William Levinson
Principal Consultant, Levinson Productivity Systems

William A. Levinson, P.E., is the principal of Levinson Productivity Systems, P.C. He is an ASQ Fellow, Certified Quality Engineer, Quality Auditor, Quality Manager, Reliability Engineer, and Six Sigma Black Belt. He is also the author of several books on quality, productivity, and management, of which the most recent is The Expanded and Annotated My Life and Work: Henry Ford's Universal Code for World-Class Success.

Topic Background:

A gage or instrument must be both accurate and precise to do its intended job. A gage's accuracy, which is ensured by calibration, reflects the agreement of its average measurement with the actual dimension of a standard. Calibration does not, however, reflect a gage's precision; its ability to get the same measurement consistently. Measurement systems analysis (MSA), or gage reproducibility and repeatability (R&R) measures the precision.

Measurement systems analysis (MSA) returns a gage's repeatability and reproducibility in terms of standard deviations. Lower is better because a smaller standard deviation means less variation. Repeatability measures the gage's ability to get the same measurement from the same part when it is used by the same inspector. This variation is inherent in the gage and the measurement procedure. Reproducibility measures the dependence of the result on the inspector. If reproducibility variation is dependent, it means that inspector judgment (such as the definition of "finger tight" or how the inspector reads a dial gage) affects the outcome.

Combination of the repeatability and reproducibility return the gage's overall standard deviation, which is in turn reflected by its precision/tolerance (P/T) ratio. This should ideally be less than 10%. If the P/T ratio is too large, then it is necessary to improve it (e.g. with better methods or gages) and/or protect the customer from borderline nonconforming parts by guard banding.

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