The Space Between Engineering and Manufacturing
The Purpose is to Make Things
I wrote the article below a while ago. As I pondered on this problem I thought I will show how the engineering documentation gets to manufacturing.
Engineering has to get the released documentation to manufacturing, if it is done in house there is a specific procedure that allows manufacturing more access to engineering. Which makes any problems with the design easier to handle.
But most manufacturing companies use outside suppliers. It is more cost effective to go out
and purchase the expertise than to manage the expensive equipment and the added
employees. But this created a space between engineering and manufacturing.
But most manufacturing companies use outside suppliers. It is more cost effective to go out and purchase the expertise than to manage the expensive equipment and the added employees. But this created a space between engineering and manufacturing.
Many large and small suppliers were established locally to support
Industries like Automotive and Aircraft manufactures. My personal experience
started with selling Boeing and their suppliers CAD/CAM software in Seattle.
Many large and small suppliers were established locally to support Industries like Automotive and Aircraft manufactures. My personal experience started with selling Boeing and their suppliers CAD/CAM software in Seattle.
So what did Engineering deliver to Manufacturing.
Pre-CAD we delivered drawings. A drawing included everything manufacturing needed to make the part. There were no other documents except references to the relevant industry standards. They were checked and signed off by engineering (designer, draftsman, checker, specialty engineers, lead engineer and supervisor).
The drawing package would be released to Document Control, which would blue print them and deliver them to the appropriate departments and blueprint counters where they were easily available to all.
Purchasing would receive their copies and proceed to get quotes from the relevant supplier. They would mail the quote package or have the supplier stop by. Rarely did the supplier meet with engineering. The parts were quoted and scheduled for delivery. Like I said everything they needed was on the drawing. If they had to come back for clarity, the process was not designed for it and the lead engineer would face some serious questions.
The engineer was "not" involved in the release of the engineering drawing package. That was totally in the realm of the drafting group. The drafting group was responsible for the sign off, release and maintenance of all of the drawings.
Enter 3D CAD
Enter 3D CAD
I had been a contract engineer for well over a decade when I was introduced to 3D CAD.
It was Computervision CADDS 4 (Computer Automated Design and Drafting System). There was no CNC at the time. These CAD systems were 3D wireframe and included a drafting module. This was their selling point, that they could make drawings faster by just dimensioning instances of the 3D wireframe model. If you changed the part all the views would change. This was a bit time consuming since you had to actually blank, change line attributes and trim the object lines.
This was the end of drawings as we knew them. We created what I have coined the AID (Associated Information Document). But they were still plotted and treated like a drawing. The 3D wireframe model was more or less useless for anything else. I think it was around 1987 that I noticed that they were using the model by IGES for what was called 2 and a half axis CNC.
I was introduced to PC Based 3D CADKEY in 1986 while on contract at Boeing. We were working with Catia 3 exchanging the 3D wireframe models by IGES. The engineering documentation was plotted on large plotters and delivered as prints. They were storing the files in a HP plot format. In the late 1980’s surfacing and solids showed up along with 3 axis CNC. By the mid 1990’s we were delivering the 3D model and the prints.
It wasn’t until the late 1990’s the PDF showed up and we could deliver the 3D model and a PDF as an email.
Many purchased Acrobat or a Acrobat clone and were instantly creating the PDF documentation. The mid-range 3D system started including direct PDF creation in their systems. The high end systems always seemed so far behind them, and they still are. By 2000 all of the major 3D CAD systems were on the PC.
But at the same time the PDF was made available Boeing was moving to Catia 5 and were incorporating the MBD (Model Based Definition) PMI (Product Manufacturing Information) format. I am not sure this decision was because they were still delivering the prints and the PDF technology was just becoming widely available and they were not aware of it. But the prints were costly and they thought PMI would solve the problem.
In the beginning the PMI included most of the dimensions, but it was soon realized that it was just to cluttered and time consuming to use it.
The decision was made to only put the basic
dimensions and cover the other dimension with profile feature control. This
was even too cluttered and it became more minimized where only the limited dimensions are now included
with complete GD&T. Look at the simple sheet metal part below.
Imagine what a complex part would look like? Yes, a mess! It is very
confusing to the designer and short cuts are taken and assumptions abound!
Look at the simple sheet metal part below. Imagine what a complex part would look like? Yes, a mess! It is very confusing to the designer and short cuts are taken and assumptions abound!
I had sold virtually every Boeing supplier a seat of CADKEY to interface with Catia 3 and 4. When they moved to Catia 5 an implemented this MBD PMI solution they were delivering native files forcing the suppliers to purchase a seat of Catia 5 or a current compatible seat of Enovia to view these PMI. This threw the suppliers into a tizzy. They didn’t know what to do.
Many of the programs could import the native Catia 5 file but there was no way to view the PMI. PMI is not a standard, it is a native format used inside the CAD system. It is delivered as a native CAD file. This is very problematic. You have to have to each of the CAD systems, a specific CAD supplied viewer or a 3rd party importer. As you can see this is a can of worms trying to keep 3 or 4 systems native PMI files current. This is a big problem for those suppliers that work with large companies that have implemented this system.
The MBD and PMI is incredibly costly and convoluted. It takes a complete PLM system to manage. That includes a staff of InfoTech folks and expensive module in the native CAD system or expensive 3rd party PLM solutions. All complicated and requiring expert training.
The small companies do not have the resources use these high-end CAD system.
They use the more cost effective mid ranged systems. The create fully detailed documents as PDF and deliver it with the 3D model. There is very little complication. The CAD/CAM systems the suppliers use can read most of the native files of the popular systems plus all of the neutral formats and with the free adobe reader they can view the documentation. No special equipment or software required. Can you imagine the additional costs the large companies that have incurred by basing their complete operation on the PLM included in a high end CAD package? It is truly shocking.
When a designer creates a completely detailed AID it serves as a second check on the design for errors or a better design. It is a format that is easily reviewed and checked. As compared to the PMI, that today just requires the minimum limited dimensions and GD&T plus a seat of the native software. If you look above, you can see how the PMI looks.
This PMI information with the other required information is adequate for manufacturing to create the parts. But this is where engineering documentation seems to becoming inadequately defined. Manufacturing is now having to go back to the companies to get clarity as described in this statistic. Sadly, this is becoming a normal process. Never was this a common practice in the past.
So what has eliminating complete detailed AIDs (drawings) accomplished?
It has not streamlined engineering, it has made the documentation less defined, the document control much more convolution, access to the information requires special software, demanding a complicated application of dimensions and annotation in a non-user friendly 3D environment and making review and checking of the documentation virtually impossible.
The PLM folks are now trying to bring their complicated process to manufacturing.
Here is the space that they are trying fill in a nutshell
The problem with engineering to manufacturing is the InfoTech industry of which the high end CAD companies have now put in charge with their complex PLM systems. The funny thing is they "think" they actually know something.
Dassault more than likely told Boeing they could do the engineering, PDM and document control.
Can you imagine a company that has been building airplanes without CAD for 70 years listening to a company with unproven technology to make such promises? Then actually put them in charge.
They could automate everything. All parts would be associated to the assemblies. Everything could be easily accessed with PDM and PLM. Nothing was farther from the truth.
I have worked with Boeing and Catia for over 30 years. Dassault is responsible for
keeping Boeing, and I suppose Airbus, a couple of the most ignorant and isolated manufacturing
companies. Their lack of interoperability is beyond belief.
I have worked with Boeing and Catia for over 30 years. Dassault is responsible for keeping Boeing, and I suppose Airbus, a couple of the most ignorant and isolated manufacturing companies. Their lack of interoperability is beyond belief.
Engineering is very simple. It is not a living body of data. The truth is, the faster the data dies (moved to archive) the better. Once manufacturing uses the engineering documentation for CNC, tooling or other planning the engineering is never accessed again. When the product is delivered all parts and assemblies should be put into one file. Like a refrigerator, once built the engineering is put away. Yes, it may be used for the basis of new products, but that product is done.
It doesn’t have to be associated except maybe in the beginning of the design, even if it matters then. The documentation should have the used on information and the assemblies still have a parts list. All parts have part numbers. Simple search program should be all that is necessary to find a part. Hell, we could go to the blue print counter or microfiche to find them. Assemblies are all in one part number.
But this concept completely escapes the data only focused IntoTech professional. The new engineers seem to have no idea. This was a fact that was well known by only the draftsman and board engineers. Sadly, with the introduction of 3D CAD, soon the draftsman was not needed anymore and their responsibilities were given without any transitional preparation to the 3D CAD engineer.
Can you image a process that was standardized and totally controlled by one profession slowly disappearing? All applicable knowledge has also disappeared and now engineering is trying reinvent the wheel, even though the wheel is sitting right in front of them with the drawing archives of the past.
So will engineering get its ducks in a row enough to realize how simple the process is?
I truly think that engineering has become overly computerized to the point it is costing more than the manual process it has attempted to replace. We used to have drafting, engineering and document control all working in an industry based standard process.
Today, just the myriad of 3D CAD systems virtually making standardization impossible. Then add the incredibly unworkable PLM and MBD document management efforts. I have said this before, there is just not enough applicable knowledge and too much vested interests to bring a cost effective standard back to engineering.
Manufacturing has escaped this onslaught of amateurs. They basically work around any of the requirements that are coming out of engineering today. WHY? They are not based on academic management. There are no "know it all" PHDs, MSMEs and InfoTechs getting in the way. Most are hands-on professionals that have to get the parts delivered or they don’t get paid. Very A to B.
This is where the rubber meets the road.
Engineering needs to take charge of the process and put the 3D CAD companies and InfoTechs back in a subservient role where they belong.
The Purpose is to Make Things that Work!
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