Gage R&R Crossed Helps assess how well the measuring system can distinguish between parts Whether the operators can measure consistently within and between themselves Assesses test variation Crossed – every part is measured by every person Balanced – the measurement is done the same number of times by each person on each part. Reproducibility – variation due to the measuring system, or the variation observed when different operators measure the same part using the same device. R&R Repeatability – variation due to the measuring device, or the variation observed when the same operator measures the same part repeatedly with the same device. R&R According to Wikipedia R&R (magazine), a music trade magazine R&R (Military), acronym for Rest and Recuperation or Rest and Recreation R&R (EastEnders), a fictional nightclub in EastEnders Rock & Republic, an American designer jeans company Repeatability and reproducibility Rescue and resuscitation 'Read and review', a term used in fanfiction by authors looking for feedback 'Recent and relevant', a requirement for those training teachers in the UK that they had experience teaching in a school that was both recent and relevant. 60 total measurements Are these numbers magical? Can I use more analysts, parts or repeats? Typical Recommended Gage R&R Study Select 3 analysts and have them measure the 10 parts 2 times at random. Collecting parts across different products thus making the test variation look much better than it is.
Mistakes include: Collecting parts that are too close together and do not represent the total variation thus making the test variation look worse than it is. This could include out of spec parts if this is expected. Typical Recommended Gage R&R Study Select a product this study will represent Collect 10 parts that represent the expected variation you would see in your process. Variable Gage R&R in a Nut-shell We want to characterize variation from the process We usually estimate this with part-to-part variation Can use an estimate from historical data We want to estimate the test variation Repeatability and reproducibility We want to know if the test variation is “good enough” for the application Ratio of Process Variation to Test Variation (% Study Variation) Ratio of Spec Range to Test Variation (P/T Ratio or %Tolerance) What Can We Get Out of a Variable Gage R&R? Measure of the % of variation in our process that is caused by our measurement system Compare measurements within and between operators Compare measurements within and between two (or more) measurement devices Provide criteria to accept new measurement systems (consider new equipment) Evaluate a suspect gage Evaluate a gage before and after corrective action (training, repair, replacement, etc) Determine true process variation Ensure that the measurement system is measuring what we want before process improvement Avoid shipping defects to our customers Avoid scrapping perfectly good parts
Reproducibility Generating a Variable Gage R&R study in Minitab How to define part or process tolerance Part selection for the study Analysis of Gage R&R in Minitab Interpreting the variable GRR graphical and statistical tools
What are we going to cover? What is the purpose of a Variable Gage R&R? Repeatability vs. 1.5 years supporting organizations related to Adhesives, Coatings and Cellulose Esters in Math, 1985 Native of Wise, VA Currently in Blountville, TN a Harding Associate Statistician 18.5 years experience in supporting Polymers and PET R&D, Technical Service and Manufacturing as well as physical and analytical testing labs. Tech, 1988 Active volunteer and leader in the Northeast TN Section of the American Society for Quality (ASQ) Hillbilly Graduate of UVA College at Wise - B.S. Harding, Jr.? Christian United Methodist Family Man Wife + 2 boys Employee of Eastman Chemical Company for 20 Years (5/10/08) M.S. Presented by Arved Harding Prepared by Arved and Wayne Ketron ASQ Tutorials Variable Gage R&R in Minitab