ASME vs. ISO
ASME vs. ISO
(OP)
Does anybody have a cheat sheet on what the differences are between the two standards? Doing a search for the differences give me many opportunities to attend classes to learn what the differences are. I just need a quick and dirty list of the major differences, any help would be appreciated.
Scorch
Scorch
Don't worry about people stealing your ideas. If your ideas are any good, you'll have to ram them down people's throats.
--Howard Aiken, IBM engineer





RE: ASME vs. ISO
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at http://eng-tips.com/market.cfm?
RE: ASME vs. ISO
According to the GD&T Pocket Guide (First Edition) by Al Neumann, Scott Neumann Copyright 1995 pg 60
"At present the ISO standards do not recognize the unique interpretation of concentricity and symmetry as defined in the ASME Y14.5M 1994 standard. The concentricity and symmetry characteristics in ISO have the same interpretations as the position characterist in the ASME Y14.5M 1994 standard"
If you are going to be using the ISO standards, I suggest buying and reviewing the following ISO Standards Handbooks:
http://www.iso.org/iso/limits.pdf
http://www.iso.org/iso/drawings1.pdf
http://www.iso.org/iso/drawings2.pdf
A cheat sheet is no substitution for actually having the standards you will be referencing in your product specifications.
RE: ASME vs. ISO
RE: ASME vs. ISO
Major differences that exist between the two standards
ht
RE: ASME vs. ISO
That was exactly what I was looking for, a good comparison of the two standards. Thanks to everybody else for your responses.
Scorch
Don't worry about people stealing your ideas. If your ideas are any good, you'll have to ram them down people's throats.
--Howard Aiken, IBM engineer
RE: ASME vs. ISO
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at http://eng-tips.com/market.cfm?
RE: ASME vs. ISO
Thanks for all inputs
SeasonLee
RE: ASME vs. ISO
RE: ASME vs. ISO
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
RE: ASME vs. ISO
The ASME Y14.5M standard is one standard that is modified once every 10 years plus or minus. Under the ASME standard, drawings are seen as individual legal documents.
The ISO standard is not ONE standard...it is a group of standards...some of which seem to conflict. Drawings are not seen as legal documents and are permitted to contain items such as manufacturing notes that are not allowed under the ASME standard.
As for callouts, the trend is to merge the two together...for example the ASME 94 picked up the ISO Datum Feature identifier. And I've been told that the next ASME release will continue that trend.
Michael
RE: ASME vs. ISO
Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group
RE: ASME vs. ISO
RE: ASME vs. ISO
So, for a cylindrical hole, you select a probing strategy and generate your points which are fed into an algorithm; the result is a generated surface which is larger than the maximum inscribed cylinder that would fit within the hole. The mating boss would be similarly probed to establish an equivalent generated surface, which would be smaller than the diameter of the minimum circumscribed cylinder. To simplify, the hole acts larger than it actually is, and the pin acts smaller than it actually is ... the actual pin which is supposed to be able to fit according to the inspection results may not fit into the actual hole.
ASME considers a mechanical mating situation where the high points of mating parts will interact. So for our example you find the largest perfect cylinder (gage pin) that will fit within a cylindrical hole (specified at RFS), and use that cylinder's axis and size as representing the hole. The mating boss will be considered as equivalent to the smallest circumscribed perfect cylinder's axis and diameter. The ASME method, by considering the worst case, ensures that actual parts will fit together when the inspection data says they should.
Now those that have spent too much time thinking this over, recognize the reality that the ASME model isn't completely accurate either. Have you ever had the three highest points on a plate actually meet the three highest points on another plate? Theoretically, but not practically. Inevitably some of the high points on one plate will slip into the low points on the mating part ... so the mating planes for each is actually going to be within the material surface anyway. So what's the difference? The ASME model introduces a comparatively minor error and still makes sure that parts will fit. ISO introduces potentially significant errors in the datuming and individual feature inspections, which accumulate with the potential that accepted parts don't fit.
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: ASME vs. ISO
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
RE: ASME vs. ISO
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com