Quality and Reliability Methods - SAS

Chapter 10 Variability Charts 165
R&R Measurement Systems
Also note that there is a platform preference (found in JMP’s preferences) that enables you to set the default
K that appears on this dialog.
In this example the report shows the statistics as a percentage of the tolerance interval (Upper Spec Limit
minus Lower Spec Limit). The values are square roots of sums of variance components scaled by a value k,
which is 6 in this example. Figure 10.12 shows the Gauge R&R report for the example shown previously,
using the data in 2 Factors Crossed.jmp.
Figure 10.12 Gauge R&R Report
Barrentine (1991) suggests the following guidelines for an acceptable RR percent (percent measurement
variation):
Table 10.3 Acceptable Variation
< 10% excellent
11% to 20% adequate
21% to 30% marginally acceptable
> 30% unacceptable
• If a tolerance interval is given on the Gauge specifications dialog, a new column appears in the Gauge
R&R report called ‘% of Tolerance”. This column is computed as 100*(Variation/Tolerance). In
addition, the Precision-to-Tolerance ratio is presented at the bottom of the report. It represents the
proportion of the tolerance or capability interval that is lost due to gauge variability.
• If a historical sigma is given on the Gauge specifications dialog, a new column appears in the Gauge
R&R report, named “% Process”. This column is defined as: