14.5m-1982 vs 14.m-1994

[PRuggiero]

Hey guys,

I'm trying to get a list of about 4-5 big changes that you would see between the old ansi y14.5m 1982 and the asme y14.5m 1994. I know it's probably dependent on the drawing but i'm just looking for the big obvious changes.

Thanks,
Pete

 

[ewh]

The best place to find these would be the 1994 standard. Some significant changes are listed in the forward and the appendices.

When the people fear their government, there is tyranny; when the government fears the people, there is liberty. - [small]Thomas Jefferson [/small]

 

[KENAT]

Yeah, look at Appendix D of 14.5 it lists former practices.

KENAT, probably the least qualified checker you'll ever meet...

 

[CheckerRon]

Yes, Appendix D.
The changes that jump out at you are:

1. Using the dumb looking ISO plunger datum symbol vs the letter within dashes.

2. Not using the circle S (RFS)symbol in the FCF, since RFS is the default with 1994.

3. Controlled root radius (CR) is now what R used to be in 1982. (Need to read section 2.15 in 1994 spec)

 

[fcsuper]

CR is under utilized from what I've seen. A lot of people still don't know what it is. I get asked about it from time to time from co-workers and shops. Then again, there's a lot of people that don't know what SR is either. I actually get frustrated when I get asked about that.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[KENAT]

I was thinking the same thing about CR fcsuper, I probably need to be more diligent about applying it.

As to frustration about SR, I see your annoyance and raise it 10 fold;-).

KENAT, probably the least qualified checker you'll ever meet...

 

[powerhound]

Don't forget the additional fundamental rules. They are the last two on the list.

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[fcsuper]

LOL (literally) KENAT

Also, please note that ASME currently has a new version of ASME Y14.5M in the works right now. It may be released this year, but don't hold your breath. I'm guessing the standard will eventually be ASME Y14.5M-2009.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[CheckerRon]

Can't wait for the new y14.5, fcsuper, hopefully I will be retired (again) by the time it comes out.

A bit off topic to the OP but since it was commnted on:

One has to be careful with the use of CR.

One of our programs added a standard drawing note that "All radii be CR unless otherwise specified."

The intention was to inspect CR's the same as the old R's were under the 1982 spec (for tangential radii only).

Inspection went hog wild, however, and started inspecting all of them with magnification and cast molds, looking for flat spots, radii reversals and tangental mismatch, and writing a lot of rejections.

Obviously, the note was too broad, and we since have restricted CR usage to highly stressed and fatigue critical areas which are identified by stress analysis (or analysts).

 

[CheckerRon]

Just to clarify, since it came up here recently:

The bottom of a blind ball end milled hole would be an SR
(not SR FULL), and an internal spherical feature >180° i.e. the reverse of Fig 5-62 would be an SØ.

AGREE??

 

[ringman]

And then there are the extended principles for Composite tolerancing. About 100 pages worth.

 

[KENAT]

Yeah, I suppose one obvious difference as I understand it is that the 94 edition is significantly longer.

KENAT, probably the least qualified checker you'll ever meet...

 

[CheckerRon]

Oh yes, PRuggiero(and ringman) There is also the PLTZF and the FRTZF ad nauseam regarding Composite Position tolerancing in the '94 ed.

 

[btrueblood]

One more - 1982 got rid of the symmetry tolerance, 1994 added it back in.

 

[fcsuper]

I don't have 1982, so maybe KENET or others can make a statement about SYM. I'm under the impression that SYM was only partially brought back, with its scope more limited than before (or is it that its scope was already so limited that many people thought POS covered it?).

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[PaulJackson]

I think that the most significant change came from the new definition of a composite tolerance as others have mentioned. The new definition established that the lower segment of the feature control frame, beyond pattern quality, controls only orientation of the pattern to the datum features specified where the 82’ standard controlled both location and orientation equivalent to two single segment controls.

The reason that change is so significant is because print dimensioning gets copied from older designs to newer ones! For instance…a composite position control on a dowel pattern that formerly provided rough control for rotation of the pattern relative to an engine’s crankshaft bores (primary), bearing thrust face (secondary), and oil pan face (tertiary) in the upper segment…then refined location of the pattern to the crankshaft bores in the lower segment… if copied… would not refine location in the lower segment according to the 94’ definition of a composite FCF.

To control the dowels equivalently with the 94’ standard in this case one would have to use two single segment position controls rather than copying the former composite FCF.
Have mistakes like this been made? Absolutely!

Unfortunately stack layouts get copied too so the problem never surfaces in design... but fortunately process tooling and gages get copied so the problem goes unnoticed. The only time a big problem occurs is when someone who knows how to interpret the composite callout but has no history with the intended control…designs a new process, codes a new CMM program, or builds a new gage and lets the pattern drift within the larger upper segment zone.

Paul.


Paul


Paul

 

[CheckerRon]

Symmetry was deleted in 1982 because it was determined that
non-circular position and profile-of-a-surface tolerances could better control symmetry.

What was brought back in 1994 in section 5.14 and Figure 5-61.

I personally find no use for it, since it treats the surface width as a composite of several elemental point measurements within the tolerance zone and does not treat the total surface as profile of a surface or position does, thus it could conceivably buy off a very jagged, rough slot, like a bad keyslot.

I guess some on the ASME Y14.5 committee envisioned applications for it, but I sure haven't found any.

Same is true for Concentricity. Runout, or position is so much better.

 

[CheckerRon]

Clarification: What was was brought back in 1994 in Section 5.14. and Figure 5-61 is a different animal.

 

[fcsuper]

What's the differences?

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[CheckerRon]

"What's the differences" requires a long answer to a short question. One that the GDT trainers love to expound on.
Since I'm not a GDT trainer, I giving the shortest answer I can.

As far as what symmetry and concentricity is today, read your 1994 y14.5.

Symmetry in the 1973 Y14.5 was defined exactly the same as Position of non-circular features RFS-RFS is in the 1994 spec. Take Fig 5-60 of 1994 Y14.5 and substitute the symmetry symbol for the position symbol, and that's what it was.
The 1973 standard even recommended that you use position instead, because that would allow usage of MMC (symmetry was RFS only).
That is why is was dropped in 1982, because Position could do the same thing and utilize both RFS and MMC.

Concentricity started out as being inspected just like runout--surface to surface. Then runout appeared in 1982 for surfaces, and concentricity became coaxiality control of axes of coincident surfaces of revolution (RFS only).
It wasn't defined very well, and what's in the 1994 ed. is better.

There are still engineering people I run into that want to use concentricity for coaxial surfaces instead of Position or Runout.

Best I can explain in a short notice.