What is it: Studies of repeatability and reproducibility are called Gage Repeatability and Reproducibility studies or GR&R for short.
What is it used for: To determine the variation in the measurement system due to the measurement equipment itself and its use by the appraisers. The variation from the test equipment is called Repeatability. A good way to think about repeatability is that it is the variation we get when we measure the same part a number of times with the same measuring device. Reproducibility variation is the uncertainty, or variation, we get between people who are measuring the same parts with the same gage. Many times this is the largest source of measurement system variation. GR&R (Gage Repeatability and Reproducibility) studies are used to evaluate the level of variation due repeatability and reproducibility.
Why use it: Measurement System Analysis (MSA) is a vital component for many quality improvement initiatives. It is important to assess the ability of a measurement system to detect meaningful differences in process variables. R&R Studies are the most widely used techniques for evaluating the variation in a measurement system and determining if the measurement system is acceptable for use. Once a measurement system is found acceptable, it is equally important to institute a formal system to manage the measurement system to ensure that it continues to be reliable and dependable. Use of structured GR&R techniques with a comprehensive calibration system for measurement devices is the only way to avoid the rubber ruler syndrome.
Where to use it: Gage repeatability and reproducibility (R&R) study can be applied in most manufacturing-related measurement systems. It may be used as:
When to use it:
How to use it: The key to a good GR&R study lies in the upfront planning. A GR&R study can be planned using the following 5 steps: