This topic contains 6 replies, has 4 voices, and was last updated by Nani 2 months ago.
We are doing Gauge R&R studies to all you equipment on an yearly basis and We want to avoid doing this on an yearly basis and come up with a system to prove that these studies are not required to be done on yearly basis.
Can you suggest something that can be done so the auditor does not give this as a finding.
Also, is there a statistical method that can prove r&r is not required based on past data.
SPC charts on known standards can confirm gages are giving good, consistent results but it’s hard to justify to NEVER redoing a gage R&R.
I want to change the interval time from 1 year to 5 years. Can you suggest me something that I can put in place to ensure that this is not given as a finding is audits.
You’ll need some data to confirm you can wait 5 years but I would be skeptical. Unless you have zero turnover and no process variation in your equipment’s operation, I doubt you could state 5 years…not that 1 year is easy to justify either.
I think that using SPC charts for daily measures of a standard part is a good way to understand if your measurments are good or not. If there is a special cause in your chart you can warn your team.
Yes, you must understand variation of your measument and your standar part. So, sometimes your special cause is due your part variation(temperature, pressure or other thing) and not because your measurement variation/not calibrated system.
Nani (you should register to get an @Name so that you will receive e-mail notices of reply’s so you don’t miss any of this profound wisdom).
As my good friend @cseider has said, there are multiple aspects of variation that a GR&R is meant to uncover and by so doing, protect the quality of the product. These are: Variation from the measurement tool, the people conducting the measurements, and the items being measured themselves.
First, tool variation. Here you want to evaluate whether the tool measures accurately as known specific values. This ensures accuracy. You don’t need to perform a GR&R for this, but you do need to calibrate the tool from time to time. Frequency can be evaluated based on past experience. The tool also may wear out over time, in which case you will need to refurbish the wear components, or totally replace the tool. So long as the tool has not changed nor worn outside of acceptability (which can be evaluated by a good calibration program) you gain little by conducting a GR&R.
Second is the people. This is more challenging as people can vary due to unrepeatable and difficult to diagnose reasons. A well trained and experienced operator can strain a muscle and suddenly not be able to perform the measurement adequately. But generally speaking, if the same cadre of people have been well trained and their environmental conditions have not substantively changed, they should continue to maintain a consistent level of variability, so again, a GR&R will add little. If the people change (actual people or the capabilities of the people), their environment changes, or the tool changes, then a GR&R is required.
Lastly are the items being measured. You might be surprised, but if you get better (more consistent) at making the parts, your measurement system may become inadequate, depending upon your desired outcome. As the distribution of the measured item is reduced, you need a tool with better discrimination (more decimals) to identify that variability. There is good news here, however. As your capability increases, the need to measure to ensure compliance decreases. With good process monitoring (observation as well as measurement) a highly capable process can reduce measurement frequency. It is typical also to change the tolerance on processes as they become more capable. Reduced tolerance makes the amount of variation of the part a larger component of that tolerance. This will necessitate more precise measurement tools, and thus, new GR&R. One mistake in conducting a GR&R is to have measured items that exhibit too little or too much variation. The items to be measured should exhibit reasonable variation based on the process used and the tolerance applied. I have had instances where the resolution of the measurement tool was not sufficient to see the part to part difference and all the variation ended up as measurement system variation.
What’s the upshot here? If nothing changed, the people maintained the same capability overall, the tool is well maintained and never wears out, and the characteristic being measured never changes in how it is created, then you might not need to do a yearly GR&R. This is a very rare circumstance. Thus a yearly GR&R is a good standard. If you can rationally support the above items with substance as to why yearly GR&R is too frequent, make your case. However, I doubt that you’ll be able to convince them. There is too much chance of these things going out of whack, and a yearly frequency seems a reasonable balance between risk of going bad and cost of performing the GR&R.
Hope that helps.