I am a Boeing trained draftsman.
At Boeing we had the ADCN (Advanced Drawing Change Notice) this was by far the most productive engineering change document ever devised.
When you are building airplanes, you are on a schedule and must keep the assembly line flowing. Due to the nature of the beast, airplanes have different customers with different configurations. This opens the door to mistakes. Any errors in design must be handled quickly and efficiently. Boeing devised the ADCN to handle this problem.
In the past Boeing would build a Mock-up. This was a full scale model
of the airplane. Where any problems were worked out prior to starting the
assembly line. With the entry of 3D CAD Boeing went to the virtual computer
airplane with the 777. No more mockups! We draftsmen chuckled when they
started making model verification assemblies. A rose is a rose by any other
In the past Boeing would build a Mock-up. This was a full scale model of the airplane. Where any problems were worked out prior to starting the assembly line. With the entry of 3D CAD Boeing went to the virtual computer airplane with the 777. No more mockups! We draftsmen chuckled when they started making model verification assemblies. A rose is a rose by any other name.
So, today we have the 787 totally driven by Catia 5 PLM/MBE/PMI. No
mockups! What did Boeing end up with? I think the first 8 did not meet the
original specs and could not be delivered to the customer. The first two are not
even flying and are donated somewhere. We had an ongoing joke in one
conversation of buying them and turning them into 787 "DreamDiners".
So, today we have the 787 totally driven by Catia 5 PLM/MBE/PMI. No mockups! What did Boeing end up with? I think the first 8 did not meet the original specs and could not be delivered to the customer. The first two are not even flying and are donated somewhere. We had an ongoing joke in one conversation of buying them and turning them into 787 "DreamDiners".
So you can add those 8 or so airplanes to the failure of PLM/MBE/PMI!
But it is still going on. This dysfunctional system is still costing Boeing
millions may billions.
So you can add those 8 or so airplanes to the failure of PLM/MBE/PMI! But it is still going on. This dysfunctional system is still costing Boeing millions may billions.
Let’s look how an error is found.
On the manufacturing floor, there are specialty engineers called liaison engineers. It is pronounced L”eye”ison in the aircraft industry (except maybe in France). They are called to a situation when something cannot be installed. Now, it is not always a problem with the engineering, it could be a problem with planning. The liaison engineers purpose is to solve the problem temporarily by writing and drawing up a rejection tag noting the change. This is part of the airplanes history. Remember, we must assume the next plane is may have the same problem. So the faster we can get this change implemented the better.
The rejection tag is delivered to the responsible engineering department, such as structures, flight deck, payloads, wing, etc. In the past, it was given to a draftsman to research. They would come up with a solution and prepare the documentation.
The ADCN was the preferred document. It was done on one or more “A” size, 8.5 x 11 vellum sheets. It would go through the complete checking and sign off process. Then be released to document control that would print and attach it to the blue print or Microfiche.
This was incredibly fast as compared to checking out and revising the drawing. The changes were expedited out to the effected parties in days. The supplier would receive the ADCN and attach it to the print. They would instantly implement the change.
When there were slow periods in the group they would assign a new draftsman to incorporate the ADCNs. It was great experience. This was called the DCN (Drawing Change Notice) and done on the original drawing that would be checked out of the vault. This would create a new revision letter.
Now many times new design requirements would demand the direct changes to the drawing. It was a bit of a pain to do this because you would be responsible to incorporate the outstanding ADCNs.
It was very smooth operation.
MBE (Model Base Enterprise)
MBE came into being at Boeing at the turn of the century with the introduction of Catia 5. This is where the 3D model becomes the design authority.
We have been using the 3D model as a pattern since the late 1980’s with the introduction of CNC. First, we supplied a 3D wireframe for 2½ axis milling then 3 Axis with the introduction of surfacing and then, of course, solid models.
Using the solid model as the design authority has huge problems.
Imagine the above scenario with the 3D model. The new 3D CAD engineer gets the rejection tag. Boeing eliminated the drafting group years ago, allowing the draftsman to disappear by attrition. You do not get an engineering job at Boeing without a BSME!
Now, of course, since we have no drawings!!! WHAT? NO DRAWINGS?
Yes, Boeing moved to MBE which has eliminated the drawing even as a supporting document.
I am sure the PLM (Product Lifecycle Management) folks quickly found that trying to keep track of two synchronized files daunting. So, they decided to eliminate the drawing all together and replace it with what? Sadly, all PLM geniuses and Infotech gurus think all CAD systems are the same and they must design a PLM system around the CAD system. OMG, that is insanity!
Let me introduce the PMI (Product Manufacturing Information).
This has to be the biggest joke on engineering since, UH, I don’t think there has been a joke on engineering. Engineering documentation was in the hands of the draftsman. They have created, maintained and supported this ancient art since the very beginnings of the documentation of engineering. I am sure they never consulted Drafting, the only ones that truly understood this process when implementing MBE. If fact, they said:
Wow NO DRAWINGS = NO DRAFTSMEN!!
The engineers can do it all!
The engineers can do it all!
I have no idea in what form the liaison engineer
gets the information to the responsible group. He can’t pull out a drawing
to review. Doe he have to have access to a seat of Catia 5 or Enovia? Hmmm,
I just don’t know. But it can't be easy.
But it can't be easy.
I did ask a Boeing representative this question at a seminar. He said “Yes that is a problem we have to work on”.
Okay, the rejection tag is now delivered to the responsible group. Now the new 3D CAD engineer must research the problem. Hmmm, again no drawings. I suppose the engineer just brings up the native assemblies and works through all the 3D models and PMI's.
Easy to view prints? Nope!! He has to view the native CAD file. Hmm How do you compare 3D models as PMIs? Time consuming beyond compare?
The engineer finally comes up with a solution and starts changing the 3D model.
CHANGING THE 3D model??
Boeing uses the overly complex history only Catia 5 system. Now, the engineer must review how the model was create. We all know the problems an engineer faces with a history based system even if he is the original designer away from the 3D model for a month. But the problem with working with a history based at Boeing is the constant turnover of engineers. Now, we all know it is a mixture of intelligence and experience that makes the CAD user. Some CAD users are more equal that others!
Here is an article that shows the heavy costs associated by depending on the CAD system to manage your engineering.
The engineer makes the changes. Now, we hope there has not been some overlooked missed feature. Hmm, do they have to do a comparison of the original and the new 3D model? How do they document the changes?
So instead of a fast ADCN, we now must directly change the 3D model. There is no drawing to mark up. In the past, we could trust the supplier to modify the drawing but the model is now sacrosanct? How ridiculous is that? Oh, I forgot, the only way you could change the model is with the native software. Oops!!
Nobody thought this through?
I have worked with many Boeing suppliers that used IronCAD or ZW3D and would modify the 3D models for CNC programming. Did Boeing know this?
Boeing even demands that the supplier runs the native Catia 5 file through a 3rd party validation program to assure that the 3D model is the same as it goes into the CNC program. This process creates an 8.5 x 11 report that has to be kept as a record. Funny, no Boeing audit has ever been done. Yet, they demand that the supplier spend around $5,000.00 for the privilege of creating parts for Boeing.
Now add the requirement to read the PMI?? PMI? how do we read the PMI? A seat of Catia 5 with the same release as the PMI, Enovia, Dassault’s expensive viewer, a third-party viewer, costly and you have to keep up to date with the latest Catia version. What if you have different customer using different software, like NX, Creo or Solidworks? We can only hope that they all release their new versions at the same time. OMG! What am I some comedian?
More about the PMI
The PMI is what these PLM geniuses and InfoTech gurus came up with to lessen the documentation data management problem. Have you seen these things? They have minimized the information to a point of silliness. Anyone that would consider the PMI and MBE as a serious engineering documentation solution:
An example of a PMI.
An example of a PMI.
So, the idea of the PMI was that data management would only have to maintain one document.
WOW, JUST LIKE THE DRAWING!!
Opps… This format is so obscure and inadequate that Boeing has 2 or more other documents that must travel with it. Sadly, these important other documents are referenced on the PMI, but usually not available to the outside supplier.
From an almost instant
document, the ADCN, to a convoluted change that probably takes weeks, maybe
months. Then send it to the supplier that has to reprogram the 3D model. What
has Boeing saved?? I have never seen any PMI for inseparable assemblies
like weldments, sheet metal with fasteners, riveted or bonded assemblies. Do
they even exist?
I have never seen any PMI for inseparable assemblies like weldments, sheet metal with fasteners, riveted or bonded assemblies. Do they even exist?
The Future of MBE?
The model based enterprise with crumble on itself as the 3D CAD systems disappear. Nothing last forever. There may be a much more productive system show up. Why in the world would we tie our engineering documentation to a CAD system. Don't ask the CAD vendor. They are not experts in how your company should be run! Their interest are in keeping you in the dark. Sadly, most CEO do not have the experience to challenge them. It all has to do with knowledgable questions.
You cannot base your engineering deliverable
Just think this through for once.
The drawing or PMI is not for the engineer!
It is for a multitude of other departments to use, such as manufacturing, purchasing, tech pubs, sales, marketing, product planning and yes engineering itself. Wait a minute, Joe, engineering has access to the original CAD files. Yes, but you want to access the "released" engineering documentation? It should be in a much easier accessible and usable format. Hopefully a drawing and a model.
We do not need access to the 3D assemblies. We just need a complete presentation how the parts go together. Any access to the native assembly should only be for change.
Here is a comment from a MSME PE forced to used MBE:
"The big problem is, any failure will be blamed on the responsible engineers and not an unworkable system. MBE is already being backstopped by drawings in many organizations that are forced to use MBE, but the drawings are frequently not in the release control process because they are not the "primary" data driving fabrication. A fine mess.."
Could we implement something like the ADCN today?
Of course, we could, we just use the drawing as the
authority again. Using the 3D model, as we did in the beginning of the
entry of the 3D model, as a basis for our documentation and a duplication
check on the correctness.
Using the 3D model, as we did in the beginning of the entry of the 3D model, as a basis for our documentation and a duplication check on the correctness.
A drawing and the 3D model are nothing more than an
inspection device. Engineering doesn't care how manufacturing makes the
part as long as it meets the specs defined in the documentation. This is why
it is so important to create unambiguous documentation.
Engineering doesn't care how manufacturing makes the part as long as it meets the specs defined in the documentation. This is why it is so important to create unambiguous documentation.
As we try and short cut engineering we open the door to Mr. Murphy to raise havoc.
The drawing, now nothing more than an associated information document generate from the 3D model, is very, very easy to create. But it offers much, much more than the 3D model.
Yes the 3D CAD engineer may have to take a
drafting class or two. I feel since they are going to replace the draftsman
they should have 3D CAD and drafting as part of their engineering
Yes the 3D CAD engineer may have to take a drafting class or two. I feel since they are going to replace the draftsman they should have 3D CAD and drafting as part of their engineering curriculum.
So, there you go!
I figure the large engineering companies will start waking up and reevaluate this convoluted PLM/MBE system. I just hope all the old draftsmen are not gone by that time.
Again, You cannot short cut engineering. That is the problem with those that have not done any engineering and have not been involved in the release of complete engineering documentation. They do not know the ramifications.
I believe 3D CAD is less cost effective than using the drawings in the past using the PLM/MBE system. There has been too much dependence on the 3D model, which really is nothing more than a pattern, yes, yes, I know a very useful pattern. But engineering documentation is much more than some feature control frames in a 3D space.
Boeing started out on the wrong 3D CAD foot in the late 1980's. Today, there is not enough applicable knowledge to pull them out of this huge costly hole they have dug with the help of Dassault's PLM and Boeing Computer Services. I have worked with Boeing and Catia for over 30 years. Dassault is responsible for keeping Boeing one of the most ignorant and isolated manufacturing companies. Their lack of interoperability is beyond belief.
Again I will reference these two articles to prove my point!