"Global" GD&T Standard?
"Global" GD&T Standard?
(OP)
I work in a regional (U.S.) development office for a Japanese company. We primarily design parts to be sourced from local suppliers and use the ASME Y14.5M standard for most of our drawings. We also source many parts from Italy, Spain, Japan and China but most of these drawings do not use GD&T. Recently our Japanese manager has requested that we determine a single standard for drawings so that anyone in the world can understand them. Unfortunately, he's leaning towards our internal standards as the way of doing things so I'm trying to gather up some more information to determine what is the best "Global" standard for GD&T. Here are a few of the issues/concerns that we have:
1. We are encouraged to use the internal standard even though we believe it is wrong. It allows things like concentricity between two parts (instead of a single solid of revolution), position with no datum references, it allows diameter symbols on things like flatness, it doesn't allow the use of MMC, and we are discouraged from using more than a couple of datums (even on parts where 5 or 6 datums would be ideal).
2. All of the engineers in this office understand the ASME standard and a few even have the certification. Unfortunately, we are told that virtually all Chinese suppliers and most Japanese suppliers don't understand the ASME standard.
3. We understand that the ISO standard is similar to ASME, but aren't clear of the differences/similarities because we do not have a copy of the standards. We use ISO design/safety standards for pretty much everything else, so it makes sense to me to use the ISO standard for GD&T as well.
Can anyone provide feedback on what standard is best for this situation?
1. We are encouraged to use the internal standard even though we believe it is wrong. It allows things like concentricity between two parts (instead of a single solid of revolution), position with no datum references, it allows diameter symbols on things like flatness, it doesn't allow the use of MMC, and we are discouraged from using more than a couple of datums (even on parts where 5 or 6 datums would be ideal).
2. All of the engineers in this office understand the ASME standard and a few even have the certification. Unfortunately, we are told that virtually all Chinese suppliers and most Japanese suppliers don't understand the ASME standard.
3. We understand that the ISO standard is similar to ASME, but aren't clear of the differences/similarities because we do not have a copy of the standards. We use ISO design/safety standards for pretty much everything else, so it makes sense to me to use the ISO standard for GD&T as well.
Can anyone provide feedback on what standard is best for this situation?





RE: "Global" GD&T Standard?
Well that's a fallacy, not all US suppliers will immediately understand ISO (some struggle with ASME but that's another issue).
Many (Most?) suppliers from around the world won't immediately understand ASME.
I'd have thought internal standards will be even more of an issue with vendors not understanding them - unless you have 'captive shops'.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: "Global" GD&T Standard?
RE: "Global" GD&T Standard?
National standards in Italy, Spain, Japan and China are either ISO-based or leaning heavily towards ISO.
American suppliers struggling with ASME still have to start somewhere - why not ISO as well?
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: "Global" GD&T Standard?
When I worked for a French company I asked them what they used. They never could give me a set of standards, the best they could come up with was "We all go to the same schools and get taught the same way". Yeah, right.
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RE: "Global" GD&T Standard?
Just out of curiosity, how many years ago did you work for French company, and how old are the standards you are using now?
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: "Global" GD&T Standard?
Best example: The change over from many national currencies to the Euro - overnight!
Sweden changes from left to right hand driving (H-day)
Worst example: UK change over to metric - years - still going on!
Absolute worst example: USA change to metric - the biggest (and most costly) screw up.
RE: "Global" GD&T Standard?
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: "Global" GD&T Standard?
GD&T stands for Geometric Dimensioning and Tolerancing; since there is no definition for Geometric Dimensioning that appears in any standard, you need not worry about it.
Dimensioning and Tolerancing standards, like Y14.5, include directly applied dimensioning and tolerancing that does not require the use of feature control frames. Drawings without feature control frames use just as much 'GD&T' on them as drawings that do. Just add "Interpret per ASME Y14.5" and tada - instant compliance. There is probably a similar note for ISO compliance.
Your problem isn't that you need a single standard, it's that you are working with companies that have not used standards and are probably unwilling to use them even if supplied for free. They don't want to educate workers, buy any software, buy any tools, or risk being able to argue for payment over potentially rejected work, and they certainly don't want to spend money up front for copies of the standards.
There is nothing in any 'standard' that could not be copied into notes or procedures that are part of a drawing package. The only benefit to a 'standard' is avoiding doing the work to copy it. You can make the drawings completely standalone of any international committee work and be just fine.
RE: "Global" GD&T Standard?
Most of the ISO specs we use are 1980-1990 vintage. Some are still active, others have been superseded. You can't start using a new revision of a spec that completely changes the interpretation of a call out on a drawing. For instance, one of the ISO surface texture specs (there are several) now has a note that only something like 86% of a surface actually has to meet the requirement. When I put a surface finish requirement on a surface it is usually because it's an o-ring sealing surface and 100% of that surface absolutely has to meet that requirement. It is just absurd to think otherwise. So we don't use the current revision of that spec. Sorry I don't have it handy to to quote exactly.
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RE: "Global" GD&T Standard?
RE: "Global" GD&T Standard?
Shrug.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: "Global" GD&T Standard?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: "Global" GD&T Standard?
I work in the US aerospace industry, and most of the companies are certified and operate under the AS9100 QA standard, which incorporates the entire ISO 9000 QA standard. But even though they operate according to what is essentially an ISO standard, the engineering drawings conform with ASME standards, use imperial (inch) dimensions, and most of the material/process standards used are SAE/AMS or ASTM specs. If your Japanese manager asks you to use a single drawing GD&T standard that a supplier in any country will understand, ASME Y14.5 should be acceptable. Boeing Commercial Aircraft has suppliers in Italy, Spain, Japan and China that work to drawings using ASME Y14.5 GD&T practices. Attached are a couple paragraphs from the ASME Y14.5-2009 preface discussing some of the issues with unifying to ISO standards.
RE: "Global" GD&T Standard?
That's what I expected.
The new generation of ISO standards is organized according to "Master plan" in order to be exact opposite of what you described - avoid gaps and overlaps in coverage.
The job isn't finished, the standards are being revised "as we speak", but there is no reason to support FUD spread by people who sell ASME for a living.
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: "Global" GD&T Standard?
ISO 5459:2011 Datums and datum systems are 81 pages and 198 swiss francs or 210 US Dollars. For one spec.
ISO has a separate spec for Cones. It's 11 pages and 58 swiss francs, or 62 US Dollars.
"ISO 3040:2009 establishes the definition of cones and specifies the graphical symbol to be used for their indication and methods for their dimensioning and tolerancing.
For the purposes of ISO 3040:2009, the term “cone” relates to right-angle circular cones only"
The Master plan document lists 37 others in the bibliography. If the average is near $100 each, that's between $3000 and $4000 dollars for the set, though some are inspection methods docs, so maybe only $2000 to replace Y14.5.
RE: "Global" GD&T Standard?
"Since many major industries are becoming more global, resulting in the decentralization of design and manufacturing, it is even more important that the design more precisely state the functional requirements. To accomplish this it is becoming increasingly important that the use of geometric and dimensioning (GD&T) replace the former limit dimensioning for form, orientation, location, and profile of part features. This revision contains paragraphs that give a stronger admonition than in the past that the fully defined drawing should be dimensioned using GD&T with limit dimensioning reserved primarily for the size dimensions for features of size. Additionally, recognizing the need to automate the design, analysis, and measurement processes, and reduce the number of “view dependent tolerances,additional symbology has been introduced for some more common tolerancing practices.
Work on this issue began at a meeting in Sarasota, Florida in January 1994. Numerous deferred comments from the public review for the previous revision, as well as proposals for revision and improvement from the subcommittee and interested parties from the user community, were evaluated at subsequent semi-annual meetings. The subcommittee divided into working groups for several meetings and then reconvened as a subcommittee as a whole to review and ensure the continuity of the revision.
Internationally, a new joint harmonization group formed in January 1993 was called the ISO/TC 3-10-57 JHG. The object was to harmonize the work and principles among ISO/TC3 Surface Texture, ISO/TC 10 SC 5 Dimensioning and Tolerancing, and ISO/TC 57 Measurement. The task of this group was to identify and suggest resolutions to problems among the three disciplines. Many representatives of the ASME Y14.5 subcommittee participated in the meetings of this group from September 1993 through June 1996. In Paris in June 1996 the ISO/TC 3-10-57 JHG became ISO/TC 213, and the responsibilities of the three other ISO committees were transferred to ISO/TC 213. Representatives of the U.S. have participated in all of the ISO/TC 213 meetings from June 1996 through January 1999. Because of difficulties, the U.S. was not represented again until anuary 2006, and representation is now ongoing. In the U.S., a similar committee was formed following the formation of ISO/TC 213 as a home for the U.S. TAG (Technical Advisory Group) to ISO/TC 213 and also to serve as an advisory committee to the three U.S. committees and subcommittees that are parallel to the ISO groups (Surface Texture B46, Dimensioning and Tolerancing Y14.5, and Measurement B89). This new committee, called H213, was formed at a meeting in 1997 by representatives of the three U.S. committees or subcommittees. H213 does not have responsibility for all three subjects as does the ISO committee, but rather serves as an intermediary to identify and facilitate a resolution to problems that may exist among the three disciplines as well as the home for the U.S. TAG."
RE: "Global" GD&T Standard?
"the use of geometric and dimensioning (GD&T)" sic
The link failed because the "&" in the gd&t part of the name.
RE: "Global" GD&T Standard?
RE: "Global" GD&T Standard?
I think the committees have too many members with no clear view of the entire scope of describing limitations to geometric variation. A large number seem to be CMM oriented and are otherwise QA/QC directed; this leaves the committee weak in analysis of variation, which in turn leaves the specs weak in variation descriptions, hence the disagreement in Fig 4-16(c) interpretation which a variational model will show does not result in the QA/QC defined behavior represented in the spec.
The only certain way out is to create software that is the single interpretation/analysis standard. It works for compiler writers and mathematicians. I don't see those skills available within ASME 14.5 and would anticipate that many who depend on teaching and consulting would push back as automated analysis eliminates the need for users to have more than a cursory understanding of the detailed effort required. With a compiler to interpret PRINT "Hello World", one doesn't need to know anything about graphics cards, memory allocation, reading the keyboard, loading or linking the code, no understanding of CPU registers or pointers or any of a hundred other processes.
A spec would still get written, but the software and spec can be cross checked without users adding their own undocumented prejudices to the mix that happen now. Where the expected spec behavior is different from what the software actually produces, one or both can be seen as needing a change. As interpretations are improved, only one place needs to be updated for everyone to have that same, new version. This ability was possible 20 years ago, and it's only become easier to accomplish. VSA was well on its way before being absorbed and buried.
RE: "Global" GD&T Standard?
Y14.5 does not cover several topics described in master plan. To compare apples to apples you have to look at Y14.100 - how many standards it contains and how much it costs. Then the difference won't be that substantial.
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: "Global" GD&T Standard?
This is referring only to ISO 14638:2015(en) Geometrical product specifications (GPS) — Matrix model, which does not include drawing management. It does include inspection methods, which I tried to estimate an exclusion of, but with ISO datum referencing alone costing more than the entire ASME Y14.5 Dimensioning and Tolerancing, it is hard to say that any comparison will put them on even footing in terms of cost.
More insidious, there are others required, that are not in this list; ISO 5458:1998(en)
Geometrical Product Specifications (GPS) — Geometrical tolerancing — Positional tolerancing, requires ISO 14660-1:Not Released), Geometrical product specification (GPS) — Geometric features — Part 1: General terms and definitions, which has already been superceded by ISO 17450-1:2011 Geometrical product specifications (GPS) -- General concepts -- Part 1: Model for geometrical specification and verification.
While I can understand why contributing employees of big companies serving on the Y14.5 committee would be compelled to 'harmonize' with suppliers working on the ISO GPS committees, ISO doesn't immediately seem attractive to emulate in any way.
Below is the list from the Master Plan, items pertaining to drawing specification are bolded, but these are only from the Master plan and do not include all drawing creation GPS standards.
[1] ISO 286-1:2010, Geometrical product specifications (GPS) — ISO code system for tolerances on linear sizes — Part 1: Basis of tolerances, deviations and fits
[2] ISO 286-2:2010, Geometrical product specifications (GPS) — ISO code system for tolerances on linear sizes — Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts
[3] ISO 463:2006, Geometrical Product Specifications (GPS) — Dimensional measuring equipment — Design and metrological characteristics of mechanical dial gauges
[4] ISO 1101:2012, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of form, orientation, location and run-out
[5] ISO 1660:1987, Technical drawings — Dimensioning and tolerancing of profiles
[6] ISO 1829:1975, Selection of tolerance zones for general purposes
[7] ISO 1938-1, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 1: Plain limit gauges of linear size
[8] ISO 2692:2006, Geometrical product specifications (GPS) — Geometrical tolerancing — Maximum material requirement (MMR), least material requirement (LMR) and reciprocity requirement (RPR)
[9] ISO 3040:2009, Geometrical product specifications (GPS) — Dimensioning and tolerancing — Cones
[10] ISO 3274:1996, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Nominal characteristics of contact (stylus) instruments
[11] ISO 3650:1998, Geometrical Product Specifications (GPS) — Length standards — Gauge blocks
[12] ISO 4287:1997, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Terms, definitions and surface texture parameters
[13] ISO 4288:1996, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Rules and procedures for the assessment of surface texture
[14] ISO 5458:1998, Geometrical Product Specifications (GPS) — Geometrical tolerancing — Positional tolerancing
[15] ISO 5459:2011, Geometrical product specifications (GPS) — Geometrical tolerancing — Datums and datum systems
[16] ISO 8015:2011, Geometrical product specifications (GPS) — Fundamentals — Concepts, principles and rules
[17] ISO 10360 series, Geometrical product specifications (GPS) — Acceptance and reverification tests for coordinate measuring machines (CMM)
[18 ISO 11562:1996, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Metrological characteristics of phase correct filters
[19] ISO 12085:1996, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Motif parameters
[20] ISO 12181-1:2011, Geometrical product specifications (GPS) – Roundness – Part 1: Vocabulary and parameters of roundness
[21] ISO 12181-2:2011, Geometrical product specifications (GPS) — Roundness — Part 2: Specification operators
[22] ISO 12780-1:2011, Geometrical product specifications (GPS) — Straightness — Part 1: Vocabulary and parameters of straightness
[23] ISO 12780-2:2011, Geometrical product specifications (GPS) — Straightness — Part 2: Specification operators
[24] ISO/PAS 12868:2009, Geometrical product specification (GPS) — Coordinate measuring machines (CMM): Testing the performance of CMMs using single-stylus contacting probing systems
[25] ISO 13385-1:2011, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 1: Callipers; Design and metrological characteristics
[26] ISO 13385-2:2011, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 2: Calliper depth gauges; Design and metrological characteristics
[27] ISO 13565 series, Geometrical product specifications (GPS) — Surface texture: Profile method; Surfaces having stratified functional properties
[28] ISO 14253 series, Geometrical product specifications (GPS) — Inspection by measurement of workpieces and measuring equipment
[29] ISO 14253-1:2013, Geometrical product specifications (GPS) — Inspection by measurement of workpieces and measuring equipment — Part 1: Decision rules for proving conformity or nonconformity with specifications
[30] ISO 14405-1:2010, Geometrical product specifications (GPS) — Dimensional tolerancing — Part 1: Linear sizes
[31] ISO 14405-2:2011, Geometrical product specifications (GPS) — Dimensional tolerancing — Part 2: Dimensions other than linear sizes
[32] ISO 15530-3:2011, Geometrical product specifications (GPS) – Coordinate measuring machines (CMM): Technique for determining the uncertainty of measurement – Part 3: Use of calibrated workpieces or measurement standards
[33] ISO/TS 15530-4:2008, Geometrical Product Specifications (GPS) — Coordinate measuring machines (CMM): Technique for determining the uncertainty of measurement — Part 4: Evaluating task-specific measurement uncertainty using simulation
[34] ISO/TR 16015:2003, Geometrical product specifications (GPS) — Systematic errors and contributions to measurement uncertainty of length measurement due to thermal influences
[35] ISO 16610 series, Geometrical product specifications (GPS) — Filtration
[36] ISO/TS 23165:2006, Geometrical product specifications (GPS) — Guidelines for the evaluation of coordinate measuring machine (CMM) test uncertainty
[37] ISO 25178-601:2010, Geometrical product specifications (GPS) — Surface texture: Areal — Part 601: Nominal characteristics of contact (stylus) instruments
RE: "Global" GD&T Standard?
But I can imagine that it is actually better to get approved and released changes for small part of a big standard within couple of years rather than wait 20 years for the next Y14.5 release.
On the number of standards - see the enclosed list of mostly outdated by now standards forming what they called "Technical Product Specifications"
And on the matter of price - all the standards on the list used to be available on CD ROM for about 350 Swiss francs.
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: "Global" GD&T Standard?
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RE: "Global" GD&T Standard?
"Know the rules well, so you can break them effectively."
-Dalai Lama XIV
RE: "Global" GD&T Standard?
Using one of the examples given by juergenwt, it is absolutely true that Euro was introduced overnight, but this was just a final effect of a huge process that had started many years before - way before anybody even knew that the common currency will be named Euro.
RE: "Global" GD&T Standard?
However - after years of preparations most national European currencies changed overnight to the Euro. Success!
Sorry - the following is a little bit off topic but it does kind of fit in with the discussion on standards. Just like trying to conform to ISO.
Compare this (the change over to the Euro) with the change from imperial to metric in the UK. Thirty years and they are still fighting it day by day!
Same thing in the US. Our vote counting politicians will be insisting on a change over the next 10, 15, 20 years and on and on. In the mean time the country suffers and our manufacturing sector has to fight this every day. With the right preparation this could be achieved in an overnight move! The emphasis is on PREPARATION! Than you do it!!
Next morning you wake up and TV reports the temp. in deg.Celsius. Your train schedule has changed to 24 hour clock. The street signs are in km - not km and miles. Your paper format changes from letter size to A4. Schools teach metric - and metric only! No more " over the next 5 years" . Period!
I would predict - this would go over better than anybody anticipates except for the nuts who worry about the inch worm.
Than - may be - we could all agree to manufacture to ONE standard. Would that be nice?