Interpretation of Limits (ASME)

This entry is part 6 of 8 in the series Dimensions and Tolerances

When reading tolerances on engineering drawings, one of the finer points that comes up during Quality inspection is how to interpret tolerance limits.  Some might look at the limits of a tolerance zone as non-absolute.

In other words, if a feature measures 14.004, but the upper limit specified on the drawing is 14.00, then one might be inclined to accept the part because 14.004 can be rounded to 14.00.  However, according to ASME Y14.5-2009 (and any earlier versions), this is false reasoning.

All limits are absolute.  Dimensional limits, regardless of the number of decimal places, are used as if they were continued with zeros.

The example given is similar to this: 12.2 means 12.20…0 (zero to infinity).

So, with that clear statement, interpretation of limits is always absolute.  A measurement of 14.004 is a nonconforming part if the upper limit is 14.00.  This is important, as it eliminates ambiguity and the opportunity to fudge with the numbers in a way that can affect quality and even product definition over time.

Author: fcsuper

As a drafter, mechanical designer and CAD engineer, I've been in the mechanical design field since 1991. For the first 8 years of my career, I was an AutoCAD professional. I utilized AutoLISP and many other AutoCAD customization features to streamline drafting activities for 6+ drafters and designers. I authored several custom functions, one of which was published in the March 1997 issue of Cadalyst Magazine. Since 1998, I've been used SolidWorks non-stop. I've worked to utilize the SolidWorks' user environment to simplify drafting and design activities for 20+ engineers. I've created this website to provide current information about SolidWorks from a variety of contributors. More recently, I am now employed by Dassault Systemes as SOLIDWORKS Sr. Product Definition Manager to improve drawing, annotation and MBD related areas.

One thought on “Interpretation of Limits (ASME)”

  1. ANSI Y 14.5M-1982, 2.4 Interpretation of limits,goes on to state: For the purpose of determining conformance within limets, the measured value is compared directly with the specified value and any deviation outside the specified limiting value signifies nonconformace with the limits. For example, specified dimension 5.000 to 5.001, the measured value is 5.0014. Should only the direct value be consider, in this case (5.001)?

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