Engineering Drawings are Dead
CAD has largely replaced the engineering drawing – embrace the change.
The era of hand-drawn engineering illustrations has come and gone. Yet so much of the engineering community both far and wide seem to hopelessly cling to the past. Of course, we're talking about engineering drawings. And yes, it's time for the drawing to die. But just like those pesky zombies on AMC’s hit TV show about failed team dynamics, it seems engineering drawings keep coming back to life. If we're not careful they'll eat our brains. Someone get me a shotgun.
Engineering documentation is at the heart of the long, storied history of technical draftsmanship. The objective back then is no different from today's challenge: represent an engineering design in the most accurate and concise way possible. Distilling the 3D reality we live in onto sheets of paper involved a carefully considered system of dimensioning and orthographic projections. These days, they might be referred to as 2D Drawings (which is a redundant term if you think about it). The system worked then and it works now. Those who are well-trained in these classical methodologies have difficulty understanding why there should be anything else. Why fix what ain't broke?
Enter the Product Manufacturing Information (PMI) revolution, otherwise known by the more grandiose engineering initiative of Model Based Engineering (MBE). No longer does product definition need to be limited by the communication medium. In other words, 3D objects can now be defined and controlled in 3D. We all think and understand 3D, because that's how we perceive the universe. But the intended value behind PMI is beyond just adding a dimension, but rather taking what was once a picture and evolving the process. Not a mere snapshot with annotations, PMI brings a persistent overlay of metadata that is queried and utilized with the model. That persistence can power automation not just in defining the product, but also manufacturing and inspecting it.
In contrast, the classic engineering drawing is fraught with limitations:
- Interpretation Issues: A properly executed drawing shouldn't be subject to misinterpretation, but that skill is starting to become something of a lost art. Unclear depictions can be problematic (i.e. which surface did that leader line touch?). More disturbingly, errors can easily escape detection. Sure, most of that can be mitigated with carefully defined GD&T, but that too seems to be a fading skill. PMI improves upon these limitations by clearly associating surfaces and endpoints, and providing validation that such dimensions do indeed make logical sense.
- Manual Inspection: Drawings necessitate reinterpretation by humans on the other side of the manufacturing lifecycle. It's another way to introduce error: the botched inspection. PMI sets the stage for automated inspection, accelerating manufacturing processes while simultaneously improving quality.
- Time is Money: This is where drawings go for the BRAINS... Simply put, in today's constantly accelerating demand to crank out the engineering in less time, drawings just take too long. Increased market pace demands more efficient processes. An engineer who's spent considerable time defining a model, shouldn't have to spend much longer documenting it. The days of modeling something then throwing it over a fence to lay it out are over. These two aspects of design must occur simultaneously, and this ultimately is only possible with model-based definition.
Yet drawings live, and at any mention of PMI or MBE, a few seasoned draftsmen will start to snicker a bit. And not wholly without cause. What drives the drawing hoard along is one simple fact. A lowest common denominator, if you will. Traditional drawings are universally accessible. And thanks to the dearth of equally accessible 3D visualization and inspection tools on most manufacturing floors, the future seems momentarily bleak. The largely proprietary 3D PMI storage formats aren't helping things either. And so these drawings just refuse to die.
Shotgun's empty. Time to reload. Drawings, your day is coming.
Interested in a post-drawing survival guide? Click here.
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About the author: (Ed Lopategui)
Technology evangelist, entrepreneur, and aerospace engineer specialized in the software tools and technology which enable engineering, design, and product development - PDM, PLM, CAD, CAE, CAM. Any views, opinions, prophecies, and sarcastic remarks are my own and are in no way associated with any current or past employers.
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