x control chart for consistency

How Can We Trust Our Measurement Process?

Measurements tell us many things. They tell us if a product is within specification, if we met our goal, if we are staying the same, if we are improving, if we are getting worse, etc. What makes a good measurement process? This is essentially asking the following question:

What does it take for us to trust our measurement process?

Think about trust. Why do we trust some people? One reason is that they are consistent – we know what to expect from them because they are consistent. The same is true of our measurement processes. We begin...

The Basic EMP Study and Gage R&R [video]

This is the final blog in a four-part series on Gage R&R studies. The first blog addressed what a gage R&R study is . The second blog addressed Gage R&R studies and process variation and determine the % of total variance due to the measurement system. The third blog examined how good your measurement system is using an Evaluating the Measurement Process (EMP) classification developed by Dr. Donald Wheeler. This blog provides a...

hardness tester

How Good is My Measurement System?

You just completed your ANOVA Gage R&R analysis. The results indicate that your measurement system is responsible for 40% of the process variance (GRR%). You look up the guidelines on the internet and this is what you see:

  • Less than 1%: The measurement system is acceptable.
  • Between 1% and 9%: The measurement system is acceptable depending on the application.
  • Greater than 9%: The measurement system is not acceptable and should be improved.

You are in trouble! 40% and it can’t be greater than 9%! What will your customer say? Should you...

test method

Gage R&R and Process Variation

This is the second in a four-part series on Gage R&R. The first blog explained what a Gage R&R study is . This blog examines the relationship between the Gage R&R results and the process variation and answers the question:

Is the measurement system capable of telling the difference between the parts or samples taken the process?

This is just another way of asking if the measurement system can be used to control the process. The basic equation describing the relationship between the...

What is a Gage R&R Study?

This is the first of a four-part blog on gage R&R. It answers this basic question:

What is a Gage R&R study?

If you google this question, you will get several answers including this one from the www.isixsigma.com dictionary:

“Gage R&R, which stands for gage repeatability and reproducibility, is a statistical tool that measures the amount of variation in the measurement system arising from the measurement device and the people taking the measurement.”

This statement is...

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