Contolling Electronic Cad Data
Contolling Electronic Cad Data
(OP)
Happy New Year Everyone!
I was wondering if there and ASME specification for controlling electronic data. Looking mostly for a generic drawing note.
Here's my dilemma:
For our complex parts we make drawings with only critical dimensions applicable to the design and have a drawing note referencing the cad model as follows:
THIS DRAWING SHALL BE MAINTAINED AND REVISED ELECTRONICALLY
THROUGH THE 3D SOLIDMODEL AND SHALL HAVE THE SAME REVISION
LETTER. THE 3D MODEL MAY BE USED FOR RAPIDPROTOTYPING OR
ANY OTHER CAD SERVICES NEEDED FOR PRODUCIBILITY OF THIS PART.
My co-workers want to use this note:
GEOMETRY OF PART PER SOLIDWORKS FILE USE FOR MANUFACTURING AND DATA VERIFICATION. MODEL: XXX-XXXX-XX.SLDPRT PART MODEL
TAKES PRECEDENCE OVER DRAWING PART IS MODELED AT NOMINAL DIMENSIONS.
A couple of things......one; I don't like the p/n in the note because it's just one more thing to edit and miss revising a drawing. two; our quality system hear requires us to buy and inspect hardware to drawings, not electronic data. I'm referencing ".....PART MODEL TAKES PRECEDENCE OVER DRAWING....." which conflicts our quality standard.
What your take on this? Also, any aerospace spec referencing controlling electronic data would be helpful.
All the Best,
I was wondering if there and ASME specification for controlling electronic data. Looking mostly for a generic drawing note.
Here's my dilemma:
For our complex parts we make drawings with only critical dimensions applicable to the design and have a drawing note referencing the cad model as follows:
THIS DRAWING SHALL BE MAINTAINED AND REVISED ELECTRONICALLY
THROUGH THE 3D SOLIDMODEL AND SHALL HAVE THE SAME REVISION
LETTER. THE 3D MODEL MAY BE USED FOR RAPIDPROTOTYPING OR
ANY OTHER CAD SERVICES NEEDED FOR PRODUCIBILITY OF THIS PART.
My co-workers want to use this note:
GEOMETRY OF PART PER SOLIDWORKS FILE USE FOR MANUFACTURING AND DATA VERIFICATION. MODEL: XXX-XXXX-XX.SLDPRT PART MODEL
TAKES PRECEDENCE OVER DRAWING PART IS MODELED AT NOMINAL DIMENSIONS.
A couple of things......one; I don't like the p/n in the note because it's just one more thing to edit and miss revising a drawing. two; our quality system hear requires us to buy and inspect hardware to drawings, not electronic data. I'm referencing ".....PART MODEL TAKES PRECEDENCE OVER DRAWING....." which conflicts our quality standard.
What your take on this? Also, any aerospace spec referencing controlling electronic data would be helpful.
All the Best,
Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2009 SP 3.0
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer





RE: Contolling Electronic Cad Data
How is your inspector going to decide which parts to accept or reject?
You need tolerances.
RE: Contolling Electronic Cad Data
Besides that, what's your take on the initial thread? Is there an aerospace spec out there you can point me too? How about the comment on ".....PART MODEL TAKES PRECEDENCE OVER DRAWING....." when our buyers buy to the print and quality dept inspects to the print.
Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2009 SP 3.0
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer
RE: Contolling Electronic Cad Data
I am not aware of such a standard. There is a standard for dimensioning and tolerancing of 3D models, but this involves you applying the tolerances, and getting the rapid prototype guys to read them.
How about a drawing note?
"UNLESS OTHERWISE SPECIFIED, ALL FACES LOCATED TO WITHIN 0.2mm WITH RESPECT TO DATUMS A, B AND C."
RE: Contolling Electronic Cad Data
x. DIGITAL PRODUCT DEFINITION PREPARED IN ACCORDANCE WITH ASME Y 14.41-2003.
y. THIS DRAWING SHALL BE USED WITH MODEL (INSERT PART NUMBER) (REVISION PER THIS DRAWING) FOR COMPLETE PRODUCT DEFINITION. MODEL GEOMETRY IS BASIC.
I created these after reviewing the info here on this site, asking my own questions on Model Based Dimensioning, and trying to read through ASMe Y14.41. From memory I based them on something in ASME Y14.41 but I can't recall the details and don't have time to look at the standard right now.
Tolerances are placed on the drawing. For some cast or molded points this has been in the form of an overall surface profile tolerance.
14.41 is a bit dissapointing from a designers point of view, as it's almost more a list of what the software needs to do, but it's the most relevant spec I can think of.
There have been a number of threads generally relating to this topic I suggest you take a look, for instance thread1103-239768: Current state of Model Based Definition.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Contolling Electronic Cad Data
I also add one line above the title block "CAD FILE: XXXXXX, REV X".
This is updated when revs change so the machinist or assembler knows which to use. It is easy to find on the dwg face.
Chris
SolidWorks 09 SP4.1
ctopher's home
SolidWorks Legion
RE: Contolling Electronic Cad Data
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Contolling Electronic Cad Data
The point of my rant is that drawings are intended to make things completely unambiguous. I am against referring to the model for use in inspection. Part of my job as a drafter/engineer is to know when to include (for example) the dimension from the left edge of a part to a hole or the right edge. If inspection is working from a model, it's up to them where to measure from.
I have in tight situations supplied a hand drawn sketch from the field for fabrication of simple parts. This was certainly quicker than even 2d drafting or 3d modeling. However, there is a reason that everything is not produced with "napkin sketches".
-- MechEng2005
RE: Contolling Electronic Cad Data
For these types of parts MBD is a real bonus, even in the current state. Tolerances (including datum's etc.) and other non geometric data still need to be defined, that has not changed.
True MBD has a way of recording this information in the model and - importantly - communicating this to other users of the data. However, because of the inadequacies of current CAD programs, the problems of not everyone using the same file format, the need for 'rules of use' on how to interpret models and some other issues not fully addressed by 14.41 etc. hybrid model/drawing is supported by 14.41 and from what I've seen is probably the best approach for most folks at this stage.
Of course, many folks see MBD as an opportunity to half ass it without addressing things like Tolerancing, but these people probably half a$$ed their drawings to so whether it's worse is debatable.
This has been discussed in depth in the other threads I mentioned, including input from folks in automotive and aerospace that live in the MBD world.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Contolling Electronic Cad Data
We use this mostly on our Complex parts such as Die castings, lost foam and plastic parts. We dimension what is functional and or critical to the parts function. Then we let the rest of the part be controlled by the 3D model. If we meet the the critical dimensions on the drawing we have a good feeling that the rest of the part meets the profile of the 3D model. But this requires good 3D modeling practice putting in all fillets, draft and accurate 3D model geometry.
RE: Contolling Electronic Cad Data
On our drawings, one of the standard notes states that the solid model is the master definition and takes precedence. We also reference any customer files that were the basis for the part in the general notes.
In the drawing title block there ia space allocated for the actual "as filed" file names (drawing and model) to be listed. These are associative to the files used, so there is no confusion when working on preliminary files or otherwise oddly named unreleased files.
Below the title block is a note specifying what CAD system was used in the drawing creation (I think that this may be covered by a standard somewhere).
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Contolling Electronic Cad Data
"THIS DRAWING SHALL BE USED WITH MODEL 123-4567 FOR COMPLETE PRODUCT DEFINITION"
I added the "MODEL GEOMETRY IS BASIC" because we mostly use this on complex parts that have some kind of overal profile tolerances. In this case the overal profile tolerances is given as 'UNLESS OTHERWISE STATED' so that any tolerances explicitly defined on the drawing take precedence.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Contolling Electronic Cad Data
RE: Contolling Electronic Cad Data
While I'm not sure how well it's been implemented, for parts that aren't MBD but we supply the model to help with CNC programming, I've made it clear to operations that our PO's or T's & C's should state that the model is supplied for reference only and that the drawing should take precedence. This is mainly to address concerns I have over our configuration control.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Contolling Electronic Cad Data
This is the reason our drawings contain the note proclaiming that the solid model is the master definition and takes precedence. It is really more of an insurance policy, as our procedures should prevent any disconnect between the model and the drawing, but mistakes have been known to happen.
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Contolling Electronic Cad Data
best,
Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2009 SP 3.0
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer
RE: Contolling Electronic Cad Data
In my view, the drawing should supersede the model...this is because anything you bother to put on the drawing is only there because of some criticality. When the drawing says nothing, then the model is law per the general notes and the profile FCF. Also, sometimes (even these days...though not that common anymore) particular shapes cannot be created in the CAD software and need to be described on the drawing itself.
Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion
&
RE: Contolling Electronic Cad Data
Wow, never saw one of those. I've had some very difficult shapes to create in CAD, but time, effort, imagination and a powerful CAD system always saw me through. I can't understand how it would be easier to define them on a drawing though.
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Contolling Electronic Cad Data
I agree with your comments. The drawing shall take precedence over the cad model. But.....it must follow the way your quality procedures are set up. This is getting into the nuts and bolts to my question. If your Qual procedure is set up to buy and inspect to the drawing, then obviously you must follow that. Most of the aerospace companies follow this beacause of FAA regulations. If your Qual procedure is set up to buy and inspect to cad model, you must follow that. Most of the automotive companies do this, and also no drawings are created.
Great comments by everyone, and thanks!
Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2009 SP 3.0
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer
RE: Contolling Electronic Cad Data
Of course, YMMV.
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Contolling Electronic Cad Data
"This document" refers to the drawing itself, which doesn't make sense to me as written. Should this read "This document controls all unspecified dimensions and features of the model." Here, the 2D document is used for QA acceptance.
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Contolling Electronic Cad Data
Most of the parts we use MBD on are curvy plastic or cast parts. So generally the drawings have very few if any dimensions on, at most just the mounting hole patterns. However, they have all the tolerance information, notes etc. as most of the time our vendors get sent dumb step or igs or parasolid files without any PMI information.
I don't get the hang up about needing a full drawing becuase that's what your QA procedures say is used to inspect against. If the drawing explicitly says to invoke the model, surely you can use the model as your primary product definition without violating your procedures? Don't get me wrong, I can see a drawing may be more usefull for inspection in some cases, I'm just questioning the concern with auditable procedures. Do you fully spec things like threads on drawings? I'm guessing not, you reference another document on the drawing and your QA procedures are find with that. So why can this principle not be extended to the model?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Contolling Electronic Cad Data
RE: Contolling Electronic Cad Data
Actually, while there were aspects that concerned me the concept of hybrid MBD (Model + partial Drawing) seemed appealing to me long ago.
It was the pure MBD with no drawing at all which still seems problematic in many ways.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Contolling Electronic Cad Data
"Art without engineering is dreaming; Engineering without art is calculating."
Have you read FAQ731-376: Eng-Tips.com Forum Policies to make the best use of these Forums?
RE: Contolling Electronic Cad Data
I appolgize that the rant went somewhat off-topic, and am glad that the other replies have not followed a topic that has already been debated, as Kenat pointed out.
However, the point of my first post was to share that I personnally do not think the model should take precedence over the drawing, which was part of the original topic.
-- MechEng2005
RE: Contolling Electronic Cad Data
Also, full blown MBD allows annotation of the model. I'm not convinced how easy this is/will be to work with but the idea is in existence and being used.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Contolling Electronic Cad Data
Think of any major car body panel and no they are radii. As for measuring it you use a CMM against the model using a surface profile.
RE: Contolling Electronic Cad Data
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Contolling Electronic Cad Data
Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion
&
RE: Contolling Electronic Cad Data
-- MechEng2005
RE: Contolling Electronic Cad Data
Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion
&