If my long-term stability chart for the measurement process shows control but a very small range and/or runs on the average chart, is this unacceptable?
You should not apply the same rules for a measurement stability chart as you would for a process control chart. If your measurement stability chart were “perfect” it would show one long flat run on the average, and endless zeroes on the range chart — after all, you are measuring the same part over and over. If that part does not change (and the surrounding conditions are stable), then the ideal condition would be for the stability chart to show no difference from measurement to measurement. In a process control chart situation, the range chart is supposed to show at least 4 levels to show proper discrimination — this rule does not apply to a measurement stability chart. Also, stratification rules probably do not apply to measurement stability charts. Points beyond the control limits should be investigated, as should trends. Such stability charts should be used with the spirit of investigating measurement system situations that appear to be unusual, or not stable (considering you are
Related Questions
- At ambient temperature the chemical resistance chart shows my process media as OK with the valve and seal materials yet Im still getting seal leaks. Whats wrong?
- When and how do I receive my structured eating plan, measurement chart, home workout and core stability workout?
- Where Does Statistical Process Control Fit into Six Sigma DMAIC?
