B
Measurement System Discrimination
When setting up to do Gage R&R Avg. and range method the MSA manual states "the sample parts must be taken from the process and represent its entire operating range". Does this mean the part tolerance or the the variation shown in your process? This can be quite different and greatly affect your results in regards to data catagories and discrimination.
At our plant we do small production runs that have good CPK's (1.33 to 2.0). In the past the process was altered to produce parts that spread across the tolerance zone. These parts were used to do the R&R studies. They even went so far as to take scrap parts and include them in the samples. I feel this skews your results and makes you think that your gage discriminates good, when actually it may be unacceptable for analyzing your process. I would think you would want to pull your sample parts from your process without influencing it. You would use linearity studies to (see page 18 of MSA) to insure gage works adequately across tolerance range.
When setting up to do Gage R&R Avg. and range method the MSA manual states "the sample parts must be taken from the process and represent its entire operating range". Does this mean the part tolerance or the the variation shown in your process? This can be quite different and greatly affect your results in regards to data catagories and discrimination.
At our plant we do small production runs that have good CPK's (1.33 to 2.0). In the past the process was altered to produce parts that spread across the tolerance zone. These parts were used to do the R&R studies. They even went so far as to take scrap parts and include them in the samples. I feel this skews your results and makes you think that your gage discriminates good, when actually it may be unacceptable for analyzing your process. I would think you would want to pull your sample parts from your process without influencing it. You would use linearity studies to (see page 18 of MSA) to insure gage works adequately across tolerance range.