Current and new customer have begun specifying profile of a surface using the U modifier as detailed in the latest version of ANSI y14.5. I have had numerous conversations over the years regarding the intent of profile is bet illustrated as attribute but customers insist on variable data. As long as the profile call our is equally distributed, the formula accepted has been: Profile = Max - Min as long as the data straddles the nominal else Profile = Maximum deviation from nominal * 2. Given an unequal profile such as: Prf .004 U .001, the profile zone is defined as +.001 / -.003 inch along the detailed surface. How do you report the "variable data" if all points on a sample range between -.003 to -.002 inch from nominal? Probably a simple solution which I cannot get to.
