Having a question with a program. My part has a profile callout of .040. The report shows +.020 -.020... And my results say .022, and is RED... I'm not seeing how a profile of .040 is out of tolerance when the result is .022?? Something just doesn't seem right....?
ASME14.5 profile is as follows:
Condition 1: If all point are positive error the reported value is: Nominal "0" to your worst positive error. Example(profile of .04 AKA +.02-+.02) no negative error... worst positive error of 0.022 will result in a failing profile of .022
Condition 2: If all point are negative error the reported value is: Nominal "0" to your worst negative error. Example(profile of .04 AKA +.02-+.02) no positive error... worst negative error of 0.022 will result in a failing profile of .022
Condition 3: Error is both positive and negative: reports the difference between the largest negative and highest positive. Example(profile of .04 AKA +.02-+.02) 0.002 worst negative error... worst positive error of 0.019 will result in a passing profile of .021
ASME14.5 profile is as follows:
Condition 1: If all point are positive error the reported value is: Nominal "0" to your worst positive error. Example(profile of .04 AKA +.02-+.02) no negative error... worst positive error of 0.022 will result in a failing profile of .022
Condition 2: If all point are negative error the reported value is: Nominal "0" to your worst negative error. Example(profile of .04 AKA +.02-+.02) no positive error... worst negative error of 0.022 will result in a failing profile of .022
Condition 3: Error is both positive and negative: reports the difference between the largest negative and highest positive. Example(profile of .04 AKA +.02-+.02) 0.002 worst negative error... worst positive error of 0.019 will result in a passing profile of .021
Thats where it gets tough to explain to an engineer!
But, in theory, if the surface checks negative .022... the profile WOULD be .044? (examples of your Condition 1 & 2)
And positive .019, negative .002, would be a profile of .038 (example of your Condition 3) ??
Even if the nominal was 1.000...and it checked 1.022, thats oversize with a profile of .044.?
So I would have to show the engineer the actually CMM hits?
Just to elaborate - the actual value for profile is defined (in ASME Y14.5.1-1994) as two values, namely the largest deviation external to nominal and the largest deviation internal to nominal. The new revision of ASME Y14.5.1, 2019, redefines the actual value of profile as essentially twice the largest deviation from nominal. The technical details are included in Y14.5.1-2019, and I'd encourage you to investigate if you haven't already.
Up until PC-DMIS 2020 R2, with the introduction of the Geometric Tolerance command, PC-DMIS had made it's own rules for displaying a measured value when choosing ASME Y14.5. Those rules are the three conditions that you've stated above. After, and including, 2020 R2, PC-DMIS displays the measured value as twice the worst deviation from nominal when choosing ASME Y14.5 or ISO 1101.
You can - if you have an older version (2014 if your info is correct) you probably need to change the registry flag "UseISOCalculations" to TRUE. This can be done through the settings editor. After a PC-DMIS restart, your profile result should show 0.044.
Lastly... since I have the older software, which shows nominal .000/ tolerance +.01, -.01, (for the profile of .020). Instead of sending the CMM print-out, an inspection report was filled out. And, as the tolerance , wrote profile of .020 and behind the results was .012 and stated oversized. Since the tolerance on the inspection report was stating "profile of .020", I think, in the results should have been .024 (double .012)?? Am I off my rocker?
