ASME Y14.5-xxxx Profile of a Surface - clarification 3

[JNieman]

I am butting heads with one of our quality department inspectors. He's our lead inspector and we disagree on the application of Profile tolerance of a Surface. I've attached a simple sketch we drew up together to argue over.

He believes that a hole, slot, etc, that intersects the surface being called out, also has a location&size tolerance applied to it BY the Profile Of A Surface tolerance.

The only foundation for his assessment is that is what he was instructed to do in a former position at a well known aerospace manufacturer, and when I slammed by copy of ASME Y14.5-2009 on his desk and told him "Prove it" - all he could come up with was citing 8.2

"Profile" where it says: "A profile is an outline of a surface, a shape made up of one or more featuers, or a two-dimensional element of one or more features. Profile tolerances are used to define a tolerance zone to control form or combinations of size, form, orientation, and location of a feature(s) relative to a true profile."

Those two sentences, he asserts, allows/forces him to check the location and size of a feature at the surface it intersects, if that surface is called out with a GD&T Profile tolerance.

I feel like I'm stuck trying to prove something DOESN'T exist while he stands fast on his status quo.

If I am mistaken, I owe him a sincere apology and a cold drink.

If I am right, I would like suggestions as to how I can further present my case more clearly.

 

[randy64]

You are correct, in my opinion. I'm no expert, so I would wait for others to weigh in before spiking the ball at your quality inspector.

Like you said, I can't fully explain how he is wrong, because he is making up something that is not in the standard. But, if you follow his logic to it's conclusion, the profile would also apply to the bottom surface, and then up the back (vertical) surface of the part. When he argues that you should only go one surface beyond, ask him to show you that in the standard. Now you have put him in the same position that he originally put you in - having to disprove something that's not there in the first place.

Hope this helps, and good luck.

 

[Belanger]

You are correct. That feature control frame (your profile callout) points to that flat surface. When you turn an edge and go into the rounded feature, it is no longer the same surface, thus it's no longer governed by the profile tolerance.

In the paragraph quoted from the standard, it says that "A profile is an outline of a surface, a shape made up of one or more features...." etc.

Well, the callout you show applies to a surface; specifically, a shape made up of ONE feature. To make profile go into the rounded slot (i.e., more than one feature), the callout would have to indicate that.

Here's a statement from the standard that will back up your position: paragraph 1.4.
"Unless otherwise specified, all tolerances apply for full depth, length, and width of the feature." (The rounded slot is a different feature.)

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[axym]

JNieman,

You are correct.

I agree with what John-Paul said. The onus is on your inspector to provide some evidence to back up his statement.

Evan Janeshewski

Axymetrix Quality Engineering Inc.

http://www.axymetrix.ca

 

[JNieman]

Ok, thanks. I guess I'm not crazy, after all. At least not because of this.

I shot an email to his boss explaining the situation. He agrees with me, and is giving his guy another day to gather evidence to support his belief. If nothing arises, our company inspection policy will be updated. We just got a new quality manager who seems to be very much more on-the-ball than our previous. His agreement with me on this topic only helps me think that way of him

I appreciate the input, all.

 

[3DDave]

Leaves me wondering what else he believes.

 

[powerhound]

What I'm wondering is how he takes a valid definition of "Profile" and somehow links it to his flawed thought process.

John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[Belanger]

Show him the all-around concept and especially the new all-over symbol in Y14.5, and that will further emphasize your point that the profile stops when the surface stops.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[JNieman]

@Belanger

I did that as well. I showed him where examples in the -2009 standard show the new symbols, and how they directly point to interior features when they /do/ want to call out those surfaces. He is a stubborn man - any inspector should be. He's been cussed out by many machinists, I'm sure, for things he was right on, so I don't expect an inspector to cave without undeniable evidence.

He's a great quality guy, who does good work and provides thorough and complete documentation. I can honestly say this is the only time I've butted heads with him - we've even worked together on providing internal GD&T coursework to train and re-acquaint every employee on these topics.

In a discussion with his boss, whom agrees with me, he's going to re-brief his quality department after giving our inspector a chance to gather any material he feels backs up his decision. I think that's quite fair and respectable.

Thanks for the many second opinions. I do not want to become an "island" in our company, sometimes, if we have no 'other authority' to appeal to, for a greater context.

 

[academix]

Hello:

Your assessment of the Profile tolerance as applied to the Surface is correct. Moreover for Profile tolerance to control location (level 4) and/or orientation (level 3), Datum Reference Frame is necessary. It is not there in the stated feature control frame. The profile establishes only form tolerance (level 2) as provided.

It would be a good idea to follow the layout of the Feature Control Frame with the Geometric Characteristic Symbol (Profile in this case) to be in the first block of the FCF.

Best regards
Natarajan R.
ASME Certified GDTP - Technologist
Dimensional Management Consultant

http://www.egs.co.in

 

[JNieman]

@academix:

Good catch! In my haste to sketch something up quick-and-dirty in Autocad LT (I normally use NX) I didn't notice my improper ordering of elements in the control frame! I guess that shows what happens when I am spoiled to using canned symbol blocks. I forget how to write it properly the manual-way!

 

[ModulusCT]

What about a boss, with fillets at it's base, so that it really is part of a flat surface being controlled by PoaS? By definition, that sounds like it qualifies. If a surface can have multiple features, as stated in the spec, who's to say that a boss or divot of some kind, while not stretching the entire length of the surface in any direction isn't also controlled? It seems to be a case of severity... Or perhaps due to a drastic change in geometry (ie. a surface interrupted by a threaded hole).

I'm a little confused about 'the line' that should not be crossed here...

I'm not a vegetarian because I dislike meat... I'm a vegetarian because I HATE plants!!

 

[JNieman]

ModulusCT, yes, there is a grey area between "singular flowing surface" and "Surface with nodules and bumps" and "surfaces with a filleted boss" but I would say that if you get to the point where you have to "rules-lawyer" the part to prove an inspection, you need further annotation to CLEARLY define the requirements and GD&T.

 

[ModulusCT]

That seems reasonable... That'll never work.

I'm not a vegetarian because I dislike meat... I'm a vegetarian because I HATE plants!!

 

[nwrichard]

Let’s look at this thing a little more completely and slower shall we? Let’s examine the diagram you used for your argument.
I took part of your diagram and put a grid system on it like you would see on a drawing, A – E and 1 – 5. I labeled this Figure 1. For simplicities sake I took only three points to discuss, B3, C3, and D3. So let’s get on with the inspection, shall we?
First we put the part on a sine block on a surface table such that the surface we want to inspect is parallel to the surface of the surface table. Then we put a suitable dial indicator on a height gauge and adjust it so when it touches the surface we are inspecting, we have one complete rotation of the needle on the dial indicator and adjust it to read zero and lock it in place.
While it doesn’t matter where you start, I will start at point E5 and work in a zig zag pattern across and down the part. When I get to point D3 my dial indicator reads -.001. At this point does this part fail the profile of surface? No, it is allowed to be that far off at that point. I continue and when I get to point C3 my dial indicator reads -.0005. At this point does the part fail the profile of a surface? No, it is allowed to be that far off at that point. When I get to B3 my dial indicator pegs out low and there is space below the indicator point on the dial indicator so the “surface deviation” the indicator is trying to measure is much larger than the .002 allowance we have per drawing. At this point does the part fail the profile of a surface? No, the drawing indicates there is not supposed to be a surface at that location so the dial indicator is supposed to read more than .002. The part still passes at this point.
Now look at the next drawing. I have kept the original figure 1 and added a figure 2. In this case figure 1 is the blueprint and figure 2 is the actual part we are inspecting. Let’s see how we do this time.
We set it up as before on the surface table and adjust the dial indicator as before. We start at E5 and begin our zig zag pattern. When I get to point D3 my dial indicator reads -.001. At this point does this part fail the profile of surface? No, it is allowed to be that far off at that point. I continue and when I get to point C3 my dial indicator pegs out low and there is space below the indicator point on the dial indicator so the “surface deviation” the indicator is trying to measure is much larger than the .002 allowance we have per drawing. At this point does the part fail the profile of a surface? Yes! This part fails at this location because the drawing indicates I should have a surface within .002 and I do not. Let’s keep going. When I get to B3 my dial indicator reads -.0005. At this point does the part fail the profile of a surface? Yes. This part fails at this location because the drawing indicates I should not have a surface at this location and I have one.
What have I just done? I failed a part for profile of a surface, but also demonstrated how profiles do in fact locate features.
As far as the inspector citing section 8.2, what section do you think he should cite??? Section 8.2 deals with (you guessed it) profile of a surface.
As far as it being mentioned only once. Does it become more valid if it is mentioned twice? Will it be even more valid if it is put as a footer at the bottom of each page? NO. It is valid being mentioned only once.
It is interesting that at the top of the forum page on this site there is a banner with a link to Tec-Ease. These people are certified to train people in GD&T and yet not one person so far that has responded has indicated they checked this site out. I checked them out and here is only part of what they have to say on the matter:”. . . There are several geometric tolerances that can be used to locate features. There is only one geometric tolerance that may be used to locate every feature on a part. The geometric tolerance is profile of a surface. Profile of a surface is the only geometric tolerance that controls the location of surfaces. Since every feature on a part has a surface, profile may be used to locate every feature. . . .”.
To find out what else they say, I suggest you go to the site and read it for yourselves. Better yet, ask other qualified, certified schools and see what they say.
In the end, I think you are wrong, and profile of a surface in reality does locate features. You owe the inspector an apology and a cold drink.

 

[powerhound]

nwrichard,

Profile of a surface is used to locate features. I don't think anyone here has argued that it doesn't. I now understand your thought process based on your explanation but it is not accurate. There is not one single thing about the slot that the profile of a surface callout controls. It is only controlling the angled surface and that's it. Your inspection setup is perfect but if there is no material where the print says there should be, it would be failure of another specification, not the profile of a surface spec. If your scenario were real, then the part would fail because the slot is in the wrong place. The profile of a surface callout is not what locates the slot.

You are the inspector in question aren't you?

John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[nwrichard]

Powerhound, I am in fact the inspector. It is interesting that every school I have contacted that is qualified to teach the subject matter agrees with my statement, in fact it is not my statement, it is what they are teaching and I am repeating. Do you know of any qualified, certified school that will put another view in writing?

 

[Belanger]

nwrichard, I have to politely disagree with you: PowerHound is correct.
This profile of a surface idea does not measure whether a surface exists or not at a given point in space. It measures a surface that is there, and sees whether its form meets a given specification. If someone decides to drill a hole where it doesn't belong (or a slot, etc.), that is an error in location for the hole, not an error in the surface that gets drilled through.

Furthermore, even if your explanation were to have some merit, the profile tolerance would have to have datum references in order to even know where that slot is on the part. The sketch in question has no datums, so you can't really impose the grid system anyway because you've artificially introduced datums to establish where the slot should be from the sides.

But again, that point about datums is irrelevant. You are attempting to locate the slot, and that simply isn't part of the surface in question.

And yes, I run a GD&T training company, and have 20 years of full-time experience in GD&T training. I find it really hard to believe that every one of my competitors agrees with you (assuming that the case was properly presented to them).

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[powerhound]

The burden of proof is on you. Not a single person on this thread agrees with you at this point.

Do you have something in writing from any of these schools to corroborate what you say?

You mentioned Tec-Ease. I hate to break it to you but everyone here knows that site and Don's tips are frequently used to illustrate certain concepts and ideas. We don't go plugging his site every time we post though, so just because no one mentioned it doesn't mean we don't know about it. Don even posts here from time to time.

There is only one geometric tolerance that may be used to locate every feature on a part. The geometric tolerance is profile of a surface. Profile of a surface is the only geometric tolerance that controls the location of surfaces. Since every feature on a part has a surface, profile may be used to locate every feature. . . .”.

I'm actually okay with this statement but Profile of a surface locates SURFACES. The surface of the slot is not what is being controlled in the OP drawing, it's the angled surface that is being controlled. If there was a PoaS callout pointing to the slot surfaces then we would all be in agreement here.

Using your inspection method--which, upon further reflection, is actually NOT perfect--how would you verify the slot location?



John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[3DDave]

Does a profile feature control frame point to the nominal 2D projected profile of the slot? No?
Then no profile tolerance applies to the slot.

"every school I have contacted that is qualified to teach the subject matter agrees with my statement"

What statement is that?

Examples:
1) Profile supplies a tolerance on acceptable variations to surfaces and features from ideal nominals.
2) Profile should apply to features it is not applied to.

"it is what they are teaching"

What are they teaching, exactly?