ASME Y14.43 and AIAG Gauge R&R rules

[Andera]

I am designing gauges, but not conducting Gauge R&R’s and I have the following questions regarding the link/connections (or lack thereof) between the gauge standard ASME Y14.43 and AIAG recommendations

1.) Is there a direct link between 10% tolerance assigned to the gauge per Y14.43 and percentage of process variation per AIAG for the measurement to be acceptable?
2.) If a company is asking to use 20%, 30% or in some cases even 40% tolerance assigned to the gauge (instead of 10%, to make the gauge more cost effective and economical) should I understand that the AIAG recommendations are not followed? Or they do not run any gage R&R’s per AIAG rules?
3.) Should then the AIAG percentages be revised accordingly (less than 30% for the MSA to be acceptable, 30%-40% marginal and over 40% unacceptable)?

4.5 Gage Geometric Tolerances Reflect Part Geometric Tolerances
Each feature of the gage that represents a feature on the workpiece is recommended to receive a tolerance between 5% and 10% of the tolerance assigned to that particular workpiece feature. The selection of a gaging policy, as described in para. 4.3, will associate the gage tolerances to the workpiece tolerances and determine whether they are contained within or additive.


According to AIAG guidelines, if your measurement system's variation is less than 10% of process's variation, then it is acceptable.
To evaluate your process variation, compare the Total Gage R&R contribution in the %Study Var column (%Tolerance, %Process) in your output with the values in the table.
Percentage of process variation Acceptability
Less than 10% The measurement system is acceptable.
Between 10% and 30% The measurement system is acceptable depending on the application, the cost of the measurement device, cost of repair, or other factors.
Greater than 30% The measurement system is not acceptable and should be improved.

 

[greenimi]

I think <10%, <10% >30% or >30% are not specific to AIAG only. You can extend the requirements to the overall MSA system

 

[metrologic]

Hi Andera,
I could be wrong, but I believe there is no direct connection between Y14.43 and the typical gauge R&R study.

Here is why:
As I understand it, gaugeRR's only assess the consistency of data, not whether the data is "correct". Imagine a micrometer that is reading offset by 1mm. Such a micrometer is not accurate, but that doesn't mean it can't measure consistently.

On the other hand, I believe Y14.43 is concerned mainly with specifying and verifying the dimensional characteristics of the various features that make up the surfaces of a gauge, since this is a necessity for measurement accuracy. Keep in mind, that even though a gauge could be perfectly made, that doesn't imply that it will perform consistently when employed for a specific measurement task.

In light of this...
1) No
2) AIAG gaugeRR recommendations can still be followed. Even if a gauge is almost useless for accurately determining pass/fail conditions it might very well be able to easily detect fluctuations in the manufacturing process.
3) No