Re: Visual Inspection Gage R&R
My understanding is that I want R&R to be +.90. Is this correct or a good goal? Is it even feasible? What is the next best step to close the gap between .7X and .90?
Rules of Thumb
Parameter Acceptable Marginal Unacceptable
E >= .90 .80 - .90 < .8
P(FR) <= .05 .05 - .10 > .10
P(FA) <= .02 .02 - .05 > .05
B .80 - 1.20 .50 - .80 or 1.20 - 1.50 < .50 or > 1.50
Are they feasible? It depends - particularly on how obvious the fail condition is to the pass condition. For surface conditions (as an example) the level of permissible scratches (how many, how deep, how long, etc.) may not achieve .90. Detecting missing components can be 1.00.
Back to the plurality of attributes per piece. Should I conduct gage R&R per attribute? Would this help me better understand our weaknesses? Sort of a pareto approach to try and pinpoint precisely what is lower our R&R? Thoughts??
You could set up the gage R&R specimens with some failing parts with single failing attributes, and others with combinations. You are not limited to the number of specimens you present to the operators. This may help sort out if there are any specific attributes or combination of attributes that create discrimination error - especially if they can exist singly in the process output. You could also do gage R&R per attribute...little more work, but may provide further insight.
I'm thinking a meeting where the inspectors sit down and calibration over the differences in pass/fail?
That may be one of the last things you do, as one you have those conversations the probability of bias will increase since the operators will
know that is what you are looking at.