RE: New Current Interesting Link - Drawing on Ex

From: <Christopher>
Date: Sun Apr 25 2004 - 23:59:00 EDT

>Regarding some of the original subject matter, is the first mistake made
>when we even discriminate between the two?
I think the first mistake is assuming that tools make the artisan. Cad is a new tool and so is FEA, but the job of the engineer remains the same: Communication of instructions based on scientific and mathematical principles, so that artisans can give a specific usefulness to materials found in nature. Engineering is a communications discipline, plain and simple.

I'm very much inclined to doubt that CAD use has improved engineering productivity much. Cheaper semi-skilled CAD operators generate drawings faster, which looks like an improvement, but the design work is poorer quality and not so well organized which costs productivity. I've seen a lot of this--poor material specification, lots of time spent in analysis and alterations and fabrication issues. FEA closely tied to CAD modelling is a lot less cost effective. Models tend to be larger and more complex and often require significant effort to overcome low quality CAD modelling. CAD geometry suitable for direct meshing is usually not available early enough in the design cycle for FEA to make a big difference. A good piping design analysis doesn't need complete details to do a seismic or thermal analysis. A simple line drawing is fine. If layout data for the seismic analysis isn't available until all the valves have been incorporated in the CAD layout with the handles oriented properly, any changes needed to stiffen the system naturally cost a lot more time and effort. This decreases productivity greatly.

CAD is a tool, not an engineering discipline. It has the same relationship to engineering as a hammer has to carpentry. Very few managers really understand this. That's why they advertize for AutoCAD or Pro/E skills rather than engineering skills. The distinction is important, because you can teach an engineer use a CAD system much faster and cheaper than you can teach an AutoCAD operator to be an engineer. But your average manager sees a guy turning out things that resemble engineering drawings, and they assume they're seeing an actual design. Most of the CAD atricles in Mechanical Engineering magazine are predicated on this as well. The editors who write them aren't engineers; they rarely even talk to real engineers.

As to why anyone would learn enough engineering to be of interest to an employer, and then throw it all away to become a manager is a mystery to me.

Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=EMIIbmiASQTxFo0jUjdCwyGoAIdft8cHhswUqG5DSuG9W6kemidBhvMM2rgz8xjyg1A_JK40GW_Iv98">chrisw@skypoint.com</a> | this distance" (last words of Gen.

___________________________| John Sedgwick, Spotsylvania 1864)

<a href="http://www.skypoint.com/~chrisw">http://www.skypoint.com/~chrisw</a> Received on Sun Apr 25 23:59:00 2004