I'm pretty new at measuring surface profile, so my doubts are, how does PC-Dmis calculate surface profile? Is there a formula for it? Does it have anything to do with XYZ deviations?
+1
JEFMAN I can't speak much for ISO. If ASME, to which version of Y14.5 must the drawing conform to? ASME Y14.5.1 clearly defines the actual value(s) for profile of a surface (from which measured values are approximated).
Be sure to check out the help file. There is a good description there of what a profile dimension is evaluating. Link:
Profile of a Surface (hexagonmi.com)
As for the math for calculating the deviation of each point, it is basically the same as the math for reporting a T-value. Here is a link to a post that has a PDF document showing the math for that:
https://www.pcdmisforum.com/forum/pc...898#post145898
The "math standard" ASME Y14.5.1 defines the actual value for profile of a surface as (t + 2g) where g is the growth parameter as defined in the document. ASME Y14.45 is a reporting standard that defines how to report the measured values if you are to comply with the document.
This is from the current Hexagon GDT training for PC-DMIS.
ASME Y14.5.1 - 2019 New Actual Value For Profile.
Actual Value. The actual value of a profile tolerance is based on an enveloping zone called the actual zone that is generated in the same way as the tolerance zone. This concept applies in the same way to equally disposed, unequally disposed and unilateral profile specifications. The generating line segment of the tolerance value t0 is lengthened or shortened by an equal amount at each end. The length change at each end is called the growth parameter g. The line segment for the actual zone has a length equal to t0+2g. The actual zone has the minimum g necessary to contain the actual surface.
If the actual zone is contained within the tolerance zone, the growth parameter g is negative.
If the actual zone is not contained within the tolerance zone, the growth parameter is positive.
If the actual zone is equivalent to the tolerance zone, g=0.