Survey results on the interpretation of the ASME Y14.5 standard

About a month ago I conducted a survey to determine how industry interprets one aspect of the Y14.5 2009 standard. I wanted to understand how the design community and verification community interprets size dimensions and geometric tolerances applied to surfaces

I posted the survey on several groups on LinkedIn. I want to start out by offering my heartfelt thanks to all of the people that participated. My intention is to use the survey results as input to ASME to help improve the Y14.5 standard.

Survey Participation Statistics

The figure above shows the statistics of how many people viewed, started or completed the survey. I am pleased to see that enough people from various countries took the survey. The sample size is significant enough to provide a good idea of the industry interpretation of Y14.5.

International Participation

The figure above is interesting, it shows the countries the people that completed the survey were from. No surprise that the majority were from the United States. I was a bit surprised that there were 96 people from outside the United States. There were responses from 25 different countries. No surprise that the majority were from the United States. I am a bit surprised that there are 96 participants from outside the United States. Altogether there are responses from 25 different countries.

Industry Participation

The figure above shows the which industries the participants were from. It appears that the Automotive industry had the most participants. The other category included: agricultural, semiconductor, oil and gas, trainers and consultants, consumer electronics, nuclear, shipbuilding, and several others. Once again, I was pleased to have a large cross-section of industries participate.

Primary Job Responsibilities

I wanted to be able to separate the design community participants from the manufacturing and verification community participants. The figure above shows the breakdown of the primary job responsibilities of the participants. The survey asked each of the major groups slightly different questions to determine what the drawing creator thought the drawing requirements were and what the drawing user thought the drawing requirements were. The verification participants received questions 1, 2, & 3. The design/engineering participants received questions 4 and 5.

Question 1 - Does the design community believe that surface texture is automatically included in the tolerance zone for size and geometric tolerances?

This question evaluated what the design community believes when they specify a size dimension or a geometric tolerance on a drawing. In other words, does a size dimension or GD&T specification include surface texture deviations in its tolerance zone? The majority of the design community said "Yes". Those who answered "other" commented that a note or additional specification needed to be shown on the drawing if the surface texture was to be included in the tolerance zone. However, there was a significant number of the design community that did not believe that a size dimension or geometric tolerance automatically included surface texture deviations. This indicates that there may be some confusion in the interpretation of the standard.

Question 2 - Does the design community believe that all surface imperfections (nicks, dents, etc.) are included in size and geometric tolerance zones?

This question evaluated what the design community believes when they specify a size dimension or a geometric tolerance on a drawing. In other words, does a size dimension or GD&T specification include surface imperfections in its tolerance zone? The design community was almost equally split on their belief of this question. Those who answered "other" commented that a note or additional specification needed to be shown on the drawing if the surface imperfections were to be included in the tolerance zone. The survey results indicates that there may be some confusion in the interpretation of the standard.

Question 3 - Does the design community believe the tolerance zone for a profile specification includes all types of surface deviations (i.e. porosity, nicks, scratches, pits, etc.)?

This question evaluated what the design community believes are the part requirements when they specify a profile tolerance on a drawing. In other words, does a profile tolerance specification include all types of surface imperfections (nicks, surface texture, pits, etc.) in its tolerance zone? The majority of the design community expressed that a profile tolerance zone includes all types of deviations.. Those who answered "other" commented that a note or additional specification needed to be shown on the drawing if the surface imperfections were to be included in the tolerance zone. The survey results indicates that there may be some confusion in the interpretation of the standard.

Question 4 - When verifying a size dimension or geometric tolerance are surface texture deviations included in the tolerance zone ?

This question evaluated if the verification community includes surface texture deviations when verifying a size dimension or a geometric tolerance. In other words, does a size dimension or GD&T specification include surface texture deviations in its tolerance zone? The verification community was almost equally split on how they handle surface texture when verify size and geometric tolerances. This indicates that there may be some confusion in the interpretation of the standard.

Question 5 - When verifying a size dimension or geometric tolerance, are surface defects (i.e pits, nodules, cracks, etc.)  included in the tolerance zone ?

This question evaluated what the verification community does when they verify a size dimension or a geometric tolerance. In other words, does a size dimension or GD&T specification include surface imperfections in its tolerance zone? The verification community was almost equally split on their belief of this question. Those who answered "other" commented that a note or additional specification needed to be shown on the drawing or simply said they don't know. if the surface imperfections were to be included in the tolerance zone. The survey results indicates that there may be some confusion in the interpretation of the standard.

Question 6 - The Y14.5-2009 standard states "the actual surface or line elements must be within the specified tolerance zone." When verifying a profile tolerance, what does this mean to you? 

This question evaluated what the verification community does when they verify a profile tolerance. In other words, does a profile specification include surface defects (in its tolerance zone? The verification community was almost equally split on their belief of this question. The survey results indicates that there may be some confusion in the interpretation of the standard.

Conclusions

Three observation about the survey results.

1. The design community is split approximately 60% / 40%. The majority believe that surface texture and surface imperfections are included in size tolerances and geometric tolerances. However, a significant portion of the design community has the opposite belief.
2. The verification community is split almost equally with approximately 48% / 47% About half believe that surface texture and surface imperfections are included in size tolerances and geometric tolerances. However, about half of the verification community has the opposite opinion.
3. I suspect that the wide variation in the interpretation of the Y14.5-2009 standard is because the standard is not as clear as it should be in this area. The Y14.5 sub-committee is working on clarifying what is included inside a size tolerance zone and in the tolerance zone of a geometric tolerance applied to a surface.

IMPORTANT TAKEAWAY FROM THIS ARTICLE !

Until this concept is clarified in the Y14.5 standard, if it is important to your part function, I think it would be prudent to add a note to your drawing or to your measurement plan to indicate what type of surface deviations are included in size dimensions and geometric tolerances applied to surfaces. Two examples of these types of  notes...
"UOS ALL SIZE DIMENSIONS AND GEOMETRIC TOLERANCES APPLIED TO SURFACES INCLUDE SURFACE TEXTURE AND SURFACE DEFECTS"  
or  
"UOS ALL SIZE DIMENSIONS AND GEOMETRIC TOLERANCES APPLIED TO SURFACES DO NOT INCLUDE SURFACE TEXTURE AND SURFACE DEFECTS"

Without a note like one of these, you cannot know which interpretation will be used for verification of your parts.

I send out surveys on GD&T and standards related topics. If you would like to participate in the surveys, sign up for my free newsletter. 

I am interested in hearing your experiences on this topic and your thoughts on this article. Leave a comment below.