Repeatability & Reproducibility הישנות ו הדירות Repeatability and Reproducibility (R & R) Studies Evaluate the precision of a measurement system. It is important that the gauge be properly calibrated Before starting the Gauge R & R Study.

Precision and Accuracy

Within Inspector Error between Inspector Error Precision Is the closeness of agreement between randomly selected individual measurement or test results. Precision Repeatability Problem: The same person (or station) can’t get the same result twice on the same subject Reproducibility Problem: Different people (or stations) can’t agree on the result obtained on the same subject Within Inspector Error between Inspector Error

Gauge Repeatability & Reproducibility Gage R&R is a study to measure the measurement error in measurement systems. The 10% rule tells us that if the percent of tolerance consumed by the R&R does not exceed 10%, the measurement system is excellent. R&R = 15% means that 15% of the variation in product measurements is due to the measurement System.

Total observed variance Each independent component of the model is variable: Product quality characteristic - Gauge, measurement error - Total observed variance in product quality characteristic measurements:

Gauge variance If more than one operator used in study then measurement (gauge) error has two components of variance: Repeatability: - Variance due to measuring instrument Reproducibility: - Variance due to different operators

Experiments to estimate the components & are called: gauge repeatability and reproducibility studies (gauge R&R studies).

Repeatability & Reproducibility Report n - number of parts r – number of operators For example : 2 operators, r=2 j=1…r 10 items , n=10 i=1…n

Repeatability = Equipment Variation Average and Range method Repeatability = Equipment Variation Standard deviation for Repeatability Where d2 is a factor that depends on the number of trials (sample size): n 2 3 4 5 6 7 8 9 10 d2 1.128 1.693 2.059 2.326 2.534 2.704 2.847 2.970 3.078 Trials 2 3 4 K1 4.56 3.05 2.50 זהו החלק של השונות, בטווח הסיבולת, הנגרמת ע"י הציוד!

Average and Range method Reproducibility = Appraiser Variation Standard deviation for Reproducibility Operators 2 3 4 K2 3.65 2.70 2.30 זהו החלק של השונות , בטווח הסיבולת, הנגרמת ע"י המפעילים!

Combined Gage Variation זהו החלק של השונות , בטווח הסיבולת, הנגרמת ע"י מערכת המדידה!