BARM,

I think the answer is NO.  Supposedly the Y14.5 is a set of tools to apply geometric theory to the parts.  It is left to the inspector as to how he goes about verifying that geometry.

In otherwords, he might use an open setup, special gages or a CMM for verification.  Whatever he might have available should be able to perform the task, that is with some effort on his part.

All that being said, if you know how the parts will be inspected, you can somewhat tailor the drawing to be a little more 'user friendly'.

FWIW

 

No there isn't and that is a great problem with the standard.

Y14.5M - 94 does not really get into the application of GD&T and also does not get into the confirmation methods either. That is one of the reasons one might see a drawing that is completely covered with GD&T including having default symbols such as Profile of a Surface in notes. It doesn't help anyone. GD&T should be used if there is a function and relationship between the features or its mating parts. Otherwise, it should not be used.

There are a few things to remember about measuring though .

If the feature control frame includes MMC, the best checking method would be a checking fixture or attribute gauge. If made correctly, it does supersede manual methods.

Measuring is not 100%. Make sure that your confidence level of the inspection method is over 90% and do not assume that a CMM is the best way.  

Dave D.
www.qmsi.ca

Thanks for your input.

It's been my experience that inspection methods of products are born out of relationships/conversations and agreements between the producer and the customer. But what if there is none or the customer is not able to provide direction?

 Is this statement "GD&T should be used if there is a function and relationship between the features or its mating parts. Otherwise, it should not be used." from the Y14.5M standard?

I've designed checking fixtures and attribute gauges. This is a whole new ballgame and in my opinion has some BIG weakness'. Now having just said that, I do know there exists a ASME standard but I haven't seen it or even heard of it's use in this industry of checking fixtures.

 

---SolidWorks 2008 SP3.0---

Inspection needs to inspect per the standards stated on the dwg.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated 10-07-07)

Chris:

Usually the drawings states "complies with ASME Y14.5M-94" but I have never seen standards for inspection on the drawing -ever!

Barm:

I learned GD&T so many years ago using a book by Lowell Foster and I always remember that statement "function and relationship" and it makes sense. The standard does not state this and there are some trainers in the subject who promote applying GD&T on everything. It just doesn't make sense to me.

I have been training in the subject for over 20 years with empahsis on measuring methods. I could not do this unless I had a lot of experience in measuring at one time.

There is an ASME standard for gages (checking fixtures) though and it should be used for gauge drawings. It is ASME y Y14.43-2003. Get a copy of it.

As I stated before, there is nothing in the standard on application including the statement on applying GD&T when there is a function and relationship. There should be though..

Dave D.
www.qmsi.ca

ASME Y14.5M-94 is the standard for inspection to follow.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated 10-07-07)

Most of the figures you see in the standard that have "means this" in the upper left corner are an illustration for inspection. It doesn't say "Use CMM" or "Starrett calipers only" but it tells you the theoretical condition that the limits of size and condition must not exceed. The way you get there is up to the inspector. Chris said it twice and I concur, you use specified standard to determine the inspection method. If you're asking if there is a standard that says HOW to inspect to Y14.5M-1994 then I concur with Dave...no.
The problem that you can run into using coordinate dimensioning (non-GD&T) is that there is ambiguity in inspection. GD&T will eliminate this. An example would be a square plate with a series of holes called out 1" from one edge. Is the intent that the holes be 1" from the edge or are they really supposed to be aligned perpendicular to the bottom edge. If the part is out of square, should the holes follow the edge or should they be perpendicular to the bottom edge? While an inspector would probably make sure the holes are 1" from the edge, there is still a chance that the part wouldn't actually work because the designer may have needed the perp requirement but didn't think about the fact that the OD of the part could actually be out of square by as much as the default angular tolerance per the implied 90 rule.

 

Powerhound, GDTP T-0419
Production Supervisor
Inventor 2008
Mastercam X2
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

As far as I am aware there is no standard on how you measure anything. For example take something as simple as a hole size, a go/no gauge will do this but it gives no indication of what is happening purely if it is in or out of limit. The inspector may wish to actually measure parts to use SPC, in nearly all cases holes get smaller as the cutting or forming tool wears and by doing this you can get (or very close too) zero rejects by replacing tooling as it becomes worn or blunt. As far as I am aware no standard tells you which route you have to go down.

As for fixture design this will depend greatly on what you are measuring, but this site gives a good general idea of some principles.
http://www.azautomotive.com/GaugeStandard.pdf


 

I would hope this might have some relevance.  I can think of GD and T as a roadmap.  The inspection is the means of getting to the intended target, (feature).  You have several methods of getting there; land, sea, or air.  Even then you have different vehicles to utlilize.

Powerhound:

I agree that your example with 4 holes can be closely controlled using positional tolerances rather than co-ordinate tolerances as long as there is a function and relationship of the holes to the mating part or within the part. If the holes are to lighten the product or have no relationship, then co-ordinate tolerancing, in my opinion, is adequate.


Chris:

Yes the standard does reflect dotted lines showing what the symbols means but not how to measure it. On flatness, as an example, should we use a CMM and 24 points, 12 points or scan the surface. We could also use a granite table, height gauge with dial indicator and 3 point set up. We would then sweep the surface. The standard does not help here.

A great example is concentricity. The standard would shows dotted lines around the datum center line but most people cannot figure this out. They usually perform a positional tolerance inspection rather than finding the median points of diametrically opposing elements.

Dave D.
www.qmsi.ca

BARM,

   The whole point of a standard like Y14.5M-1994 is that it defines the meaning of everything you apply to your drawing.  Even if you do not use GD&T symbols, the standard explains how your +/- dimensions are to be interpreted.  

   A basic assumption about fabrication drawings is that you should not specify the process.   You should specify only the results, and let the fabricator figure out how to do it.  Is there any reason this attitude should not be applied to inspection?

                   JHG

I have never seen a standard as to "how" to do inspection. That comes with training.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated 10-07-07)

drawoh,

"Is there any reason this attitude should not be applied to inspection?" How about when one method rejects the part and another method accepts the same part?

---SolidWorks 2008 SP3.0---

BARM,

   Your drawings should define what dimensions are acceptable.  Your inspection method should determine what the as-fabricated dimensions are.  If I have one inspection method that accepts a part and another inspection method that rejects the part, I would review my methods and recalibrate my tools.  

                        JHG

Yeah, I personally would think that inspection methods do not belong on ASME Y14.100 and child standards.  There is specific instructions on how to provide information regarding interfacing if desired, but this should be the limit, imo.

How to inspect is up to the drawing itself, S.O.P.'s, the actual equipment used (and their instructions) and experience in the Quality Engineering field to a level required for such inspections.  I can imagine that it would be hard to create some sort of national/international standard for this.

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

There is no standard, but something has been initiated called "ASME Y14.45 - 20XX, MEASUREMENT DATA REPORTING PRACTICES"

http://cstools.asme.org/csconnect/PublicReviewPage.cfm?SearchType=Pins

When GD&T is properly applied to a drawing there is only one configuration in which to inspect the part. The GD&T will tell you how to configure the part. Primary datum contacts first (3 points of contact) secondary datum contacts second (2 points of contact) and tertiary datum contacts third (1 point of contact). This is the only acceptable way to check a part that is manufactured to a GD&T print. There will be no case of one method accepting the part and one method rejecting it unless one method is not appropriate such as a CMM vs. a hard gauge. A part being acceptable in one configuration and rejected in another is the fault of the drawing, not your inspection methods or equipment. This is one of the fundamental reasons GD&T came into existence. If you have a drawing that uses coordinate tolerancing only, you can use whatever method you want to come up with an acceptable part.

Powerhound, GDTP T-0419
Production Supervisor
Inventor 2008
Mastercam X2
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

Level 2:  Dimensioning and Tolerancing of Functional Gages and Fixtures and Variables Data Collection and Analysis
           [per the ASME Y14.43-2003 Standard]
    
All those persons with an interest in learning the new rules, regulations and preferred ASME and ANSI practices per the newly approved standard Y14.43-2003 on the design, dimensioning and tolerancing of GO gages, NOGO gages, Functional Gages (to verify geometric tolerances) and Fixtures (to stabilize parts for manufacturing and inspection).  Anyone interested in the collection and analysis of variables data using Coordinate Measurement Machines and other measurement tools.

•    Gage Designers        •    Fixture Designers
•    Manufacturing Engineers        •    Process Engineers
•    Quality Engineers    •    Inspectors
•    Anyone wishing to strengthen their knowledge of Geometric Dimensioning and Tolerancing  

  
Participants in this seminar will learn the rules, principles and practices of gage and fixture design, dimensioning and tolerancing per the newly approved standard, entitled Y14.43-2003 Dimensioning and Tolerancing Principles for Gages and Fixtures, from the chairman of the Y14.43 committee, James D. Meadows.  The standard on which this seminar is based extends the information contained in ASME Y14.5M-1994 (which is not a gaging standard).  It shows the physical embodiment of the theory of Geometric Tolerances as it pertains to manufacturing and inspection.  It teaches that the choices we make on how we design, dimension and tolerance gages and fixtures determines whether good parts will be rejected and/or bad parts will be accepted.  Participants will also view and discuss the collection of variables data from Coordinate Measurement Machines and a wide variety of inspection equipment, then analyze the data to determine compliance with geometric tolerances.
  
Participants Will Learn to Apply the Principles of:
•    Gage and Fixture Design, Dimensioning and Tolerancing per the newly approved Y14.43-2003 standard.
•    Variables data collection methods and datum establishment by Coordinate Measurement Machines and other inspection tools common to Daimler/Chrysler.
•    Techniques to Analyze Collected Variables Data
   
  
            General Course Outline
    
-    Collecting Variables Data Using Coordinate Measurement Machines, Optical Comparators, Gear Analyzers and other Inspection Equipment Common to Daimler/Chrysler
-    View Inspection Procedures Filmed at Daimler/Chrysler
-    Boundary Verification versus Tolerance Zone Verification
-    Assess Part Compliance with Given Geometric Tolerances
-    Analyze Variables Data
-    The Function and Use of Gages
-    The Gage Tolerancing Policies
-    Statistics
-    How to Make Gage Geometric Tolerances Reflect Part Geometric Tolerances
-    Tolerance Stack-Up on Gages
-    Gage Definition Requirements
-    Principles of gage Size and Full Engagement of Features
-    The Effect of a Gage on a Part Being Measured
-    Free State and Restrained State Inspection Rules on Flexible Parts
-    GO and NOGO gage Design Rules and Principles
-    Functional gage Design to Verify Assemblability and Orientation in 3D Space
-    Gaging Temperatures
-    Economics of Gage Design
-    Gages vs. Other Inspection Methods
-    Plug Gages
-    Spherical Ended Rod Gages
-    Full Form Cylindrical Ring Gages
-    Snap Gages
-    Setting Master Disc; Setting Master Ring
-    Differentiation
-    Datum Feature Simulator Design, Dimensioning and Tolerancing
-    Gage Element Configuration Design, Dimensioning and Tolerancing
-    Datum Target Simulator Design, Dimensioning and Tolerancing
-    Material Condition Modifiers on Gage Elements
-    Material Condition Modifiers on Datum Feature Simulators
-    Design Constraints
-    Coefficient of Expansion
-    Repeatability
-    Tolerance Calculation for Gages and Fixtures
-    Tolerance Distribution for Gages and Fixtures
-    Usage:  Environmental Condition; Certification and Calibration; Referee Gaging; Principle Alignment; Measurement Force; Handling
-    Similarities and Differences between Gages and Fixtures
-   Gaging Parts that Use the Regardless of Feature Size Modifiers


 

          Y14.43-2003 GEOMETRIC DIMENSIONING
                 AND TOLERANCING
          Principles for Gages and Fixtures
  

Y14.43-2003 Dimensioning and Tolerancing
Principles for Gages and Fixtures
Committee Chairman: James D. Meadows
  
Published 2003
108 pages / $85.00
ISBN: 0-7918-2808-5
  
This standard extends the information contained in ASME Y14.5M-1994 (which is NOT a gaging standard). This is for all those persons with an interest in learning the new rules, regulations and preferred ASME and ANSI practices on the design, dimensioning and tolerancing of GO gages, NOGO gages, Functional Gages (to verify geometric tolerances) and Fixtures (to stabilize parts for manufacturing and inspection).

This Standard presents the design practices for dimensioning and tolerancing of gages and fixtures used for the verification of maximum material condition (MMC) size envelopes and virtual condition boundaries generated by geometric tolerances controlled at maximum material condition. Examples of gages used to inspect workpieces using regardless of feature size (RFS) are shown in Appendix C. These practices focus on the design of receiver-type gages, which collect attribute data when used or the verification of workpieces dimensioned and toleranced in accordance with ASME Y14.5M-1994.


 

Will Y14.43-2003 become effectively obsolete with the new Y14.5?

Believe it if you need it or leave it if you dare. - Robert Hunter
 

No, actually they are very much the same except for a few changes that will not affect the Gaging Standard, verification of maximum material condition (MMC) size envelopes and virtual condition boundaries generated by geometric tolerances controlled at maximum material condition are still the same. These practices focus on the design of receiver-type gages.