ISO 8015 6

[ak762]

I would like to open new thread in continue to thread1103-196260: Tolerance analysis ISO2768
When I have read previous thread there was concerns about how to use ISO 2768-mK in correct way.
From my opinion it is sort of alternative solution to well known tolerance system x.x - x.xxx with nominal dimensions.

But ISO 8015 Technical drawings - Fundamental tolerancing principle. more cause anxiety to me.
It is stated: Each specified dimensional or geometrical requirement on a drawing shall be met independently, unless a particular relationship is specified.
As I understood from my background this standard destroy all engineering practice regarding to application limits and fits.
Designer apply fits by engineering calculation or recommendation from proved design.
If I will take into consideration fit for mating features of components I can not be sure with fit due to independently.

Are someone represent drawing under governing ISO 8015. How you overcome above mention situation?

 

[KENAT]

I don't think that's quite the intent of 2768, it essentially replaces the 'block tolerance'.

The first section assigns different +- dimensions based on the tolerance class you specify on the drawing & the size of the dimension. So a sort of direct replacement for the typical block tol.

The second section assigns certain controls again based on class and I think size but I can't recall for sure. This goes a bit further than most title block tolls and begins to address the otherwise apparently missing controls.

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[pmarc]

Dean,

Answering to your questions one by one:

"This illustrates why buying ISO 1101 plus the other standards you need costs something like $1800..?"
Yes, I agree. ISO 1101 as a stand alone standard is not enough for complete definition of dimensioning and tolerancing rules. If you take a look at annex C to ISO 1101, you will find general GPS standards matrix and you will see how many cells are not covered by the standard. Saying very briefly ISO's approach for the future is that every cell in the matrix will be covered by appropriate standard(s). Unfortunately this will not be done by a single standard so it is easy to imagine how much money would have to be spent if somebody is willing to have a complete set of documents.

So, am I correct if I say that there is a choice between using circle E or citing 2768, if using ISO standards?
You do not have to cite ISO 2768 to omit necessity of using E in the circle for every dimension. To invoke Envelope Requirement you can simply put a statement in general notes somewhere on a drawing - something like lot of ASME folks do while instead of putting hundreds basic dimension symbols a note "UNLESS OTHERWISE SPECIFIED ALL DIMENSIONS ARE BASIC" is placed.

Maybe the major point of this thread is that 2768 (either mH or mH-E) should always be referenced if 8015 is referenced?
This can not and should not always happen. The reason is that 2768 applies only "to the dimensions of parts that are produced by metal removal or parts that are formed from sheet metal". So tolerances for any other manufacturing methods are not covered by this spec. There are other standards that deal with tolerances for castings for instance, but of course it will be like an utopia to think that every manufacturing method will have its corresponding standard in the future.

Can 8015 be "safely" referenced by itself, with no accompanying reference to 2768?
Yes, it can under certain conditions. As long as a drawing somehow defines mutual relationship between size and shape of features and there are linear/angular tolerances clearly defined, I would say referencing to 2768 is not always needed - especially if we are aware of limited applicability of 2768.

From my experience -- if a drawing deals with a metal part and general tolerance approach is used together with envelope requirement as a default condition -- following notes are sufficient for definition of at least fundamental rules for GD&T:
- DIMENSIONING AND TOLERANCING ACCORDING TO:
- ISO 8015
- ISO 1101
- GENERAL TOLERANCES ACCORDING TO:
- ISO 2768-mH-E

I think it is a subject for other discussion whether the general tolerances according to 2768 are clear, unambiguous and really helpful. Huge can of worms might be opened.

 

[KENAT]

Perhaps more of a vat than a can;-).

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[ak762]

There is something like general geometrical tolerances concept which is quite common in ISO world, but little known in US. It assumes that as long as there is a reference to appropriate standard about general geometrical tolerances on a drawing there might be no need for specifying particular geometrical tolerance.

I know several systems of general tolerance representation what can be noted in drawing.
x.x - x.xxx with nominal dimensions
GENERAL TOLERANCES ACCORDING TO ISO 2768-mH
GENERAL TOLERANCES ACCORDING TO: hole H14, shaft H14, others +/-IT14/2

If I correct understand any of them can be use both with ASME 14.5M and with ISO 8015.

To CheckerHater Yes, I like this caliber
Regarding to buy or not advanced tool. At least I would analyze everything in detail. If I understand I can not provide technical requirements then better refuse from bargain instead to make scrap.

But let's go back to cylindrical parts.Now imagine two of them – one very short, say 30mm and another very long, 1000mm. Both still 10mm dia.

Good sample from real business.
If short part satisfy to assembly function with current drawing but cut off from long rail do not it is mean you should revise business process instead adjust standard.
Both GD&T and ISO 8015 are part of system (code) only what try to describe real life in virtual reality.
When I listen arguments from production staff I am wondering do they know how engineering requirements for product appear.
I believe it is well known chain Science->R&D->Design->Manufacturing

KENAT well input here thread1103-196260

In fact I think I have an issue with this standard overall, it seems more concerned about suiting manufacturing than ensuring functionality! Sure manufacturability is very important, but not at the expense of function!

 

[KENAT]

AKS, because of that apparent discrepancy in view point and the effect it has on the spec, I'd be very hesitant to try and claim my drawings were to Y14.100 series/ASME Y14.5M-1994 but reference 2768 for tolerances. I think there would be clashes in some fundamental principles which would lead to confusion and could result in legal ambiguity in the worst case.

As to "Science->R&D->Design->Manufacturing" being the chain, it may be well known but not necessarily well followed.

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[fcsuper]

I ditto KENAT's concerns on this topic. Even changing a drawing from ASME Y14.5M-1994 to ASME Y14.5-2009 can create interpretation issues. The problems are compounded when trying to change it from ASME to ISO. I would recommend a general push back with the argument that changing the referenced standard could jeopardize design intent.

Matt Lorono, CSWP
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[fsincox]

Remember the "K" in -mK does cover form, orientation and location to some extent, it is just not the "perfect" envelope that we are comfortable with. The envelope can be envoked as noted above. On the other hand, we do not cover orientation and coaxiality as defaults in our tolerancing standard.
Frank

 

[fsincox]

"Could someone reference to Independence principle regarding to DIN",
this is the independancy principle we are talking about. DIN was where it cam from as far as I know, I am not an ISO historian, but I do have some old german standards in english.
Frank

 

[GMIracing]

Could someone reference to Independence principle regarding to DIN?

DIN 7167:1987 - Relationship between tolerances of size, form, and parallelism; envelope requirement without individual indication on the drawing.

my take after reading this standard: if the drawing is based on DIN standards and contains no reference to ISO 8015, then the envelope requirement shall apply. (ASME rule #1, Taylor Principle) But only for straightness, flatness and concentricity.

This illustrates why buying ISO 1101 plus the other standards you need costs something like $1800..?

ISO Standards collection - Technical Product Specification (TPS)

http://www.iso.org/iso/publications_and_e-products/handbooks_paper_cd.htm

it contains quite a few, if not most of the standards a design engineer would use on a semi-regular basis. the main highlights:
ISO 128, ISO 286, ISO 1101, ISO 1302, ISO 2768, ISO 5458, ISO 5459, ISO 8015, ISO 8062, ISO/TR 14638 + many more.

costs 366,00 CHF ~410USD

While not quite being a completely equivalent, I look at it as this single handbook containing the ISO versions of most from the ASME Y14 standards. What would buying all of the ASME Y14.x standards cost?

 

[CheckerHater]

GMIracing: "What would buying all of the ASME Y14.x standards cost?"

Approximately $2000. They used to offer discount if you buy the entire package, but not anymore. Even then still about $1800.

Don't take my word for it - make your own shopping list. You may probably need:

ASME B46.1 Surface Texture (Surface Roughness, Waviness and Lay)
ASME Y14.1 Decimal Inch Drawing Sheet Sizes and Format
ASME Y14.1M Metric Drawing Sheet Sizes and Format
ASME Y14.2M Line Conventions and Lettering
ASME Y14.3M Multiview and Sectional View Drawing
ASME Y14.4M Pictorial Drawings
ASME Y14.5M Dimensioning and Tolerancing
ASME Y14.6 Screw Thread Representation
ANSI Y14.7.1 Gear Drawing Standards, Part 1 for Spur, Helical, Double Helical and Rack
ANSI Y14.7.2 Gear and Spline Drawing Standards, Part 2 for Bevel and Hypoid Gears
ASME Y14.8M Castings and Forgings
ASME Y14.13M Mechanical Spring Representation
ASME Y14.18 Optical Parts
ASME Y14.24 Types and Applications of Engineering Drawings
ASME Y14.34M Associated Lists
ASME Y14.35M Revision of Engineering Drawings and Associated Documents
ASME Y14.36M Surface Texture Symbols
ASME Y14.38 Abbreviations and Acronyms
ASME Y32.2.6 Graphic Symbols for Heat–Power Apparatus
ANSI Y32.10 Graphic Symbols for Fluid Power Diagrams

The list will vary depending on the industry, so you may add various ASTM / IEEE / SAE / Government, etc. to taste.

Good Luck!

 

[fsincox]

The pamplet I have from ASME lists the price of ASME Y14.5-2009 as $169.00 alone.
Frank

 

[KENAT]

In the UK there was a 'compendium' of all the relevant Iso standards called BS8888, I recall it being pretty pricey but maybe my memory isn't what it was.

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[fsincox]

Ken,
I agree, the point is they are all "pricey". IMHO, These are more than an individual would want to spend of his own money, just to stay up to date in their profession, so we wait for the company to do it. After a certain amount of time it should become public property, at least the old versions, part of the public historic record.
Frank

 

[KENAT]

Something like, any registered US company can get one copy of the ASME specs at a discount price or something like that would be nice, though since ASME isn't ANSI and hence isn't actually a govt body I doubt that'll happen.

In the UK my company had access to an online site for BS specs where you could access almost all of them (except for some old ones that hadn't been scanned yet). They also had an agreement with the public library system for borrowing standards.

Maybe some companies have similar here, mine sure doesn't though.

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[fcsuper]

The 100% commitment for ASME or ISO is very pricey. I think ISO bets ASME in terms of overall cost for the complete standard. The other problem is the ISO varies by country anyway, as each region implements its own variation on it. Though it is an international standard, it's not a world standard. IF they would take the world "American" out of the ASME name, I would think it would more likely to be be considered as international.

Matt Lorono, CSWP
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[DeanD3W]

Please correct me if I'm wrong, but I believe that it would cost at least 10X the Y14.5 price to purchase the 15 or so ISO standards it takes to assemble a rough equivalent.

With Y14.5, much more is covered in one standard than with ISO's approach.

Dean

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[KENAT]

I think that's the kicker, most of the day to day drafting stuff that I have to look to the standards for guidance on is in 14.5. I look at the other Y14 standards much less often.

To get the equivalent ISO information, you need multiple standards.

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