Is Our CAD Use All Wrong?

The question of whether the "D" in CAD is more about enabling good drafting or good design is the subject of a heated debate in the Desktop Engineering LinkedIn Group. Cydesign's Derek Cheng posited the idea that drafting is not the same as design. He says companies can run into trouble if they leverage CAD too early in the cycle to create beautifully meshed and rendered 3D models prior to do the mathematical work that is foundational to good design.

"Design means understanding what the requirements are, the goals of the project, and ensuring that what you do will work," Cheng maintained." Comparatively, he said drafting is spatial, answering the questions of will something fit and how will it look when it fits. "Design is much, much bigger," he contended. "It requires an understanding of physics, motion dynamics, cyber-electromechanical engineering, and the user experience. Sadly, we often skip the math and go right to drafting it, prototyping it, and testing it."

Matthew Ian Loew, an independent consultant and a former engineering professor, was equally passionate that CAD is oftentimes misused, particularly when the workflow involves doing detailed CAD designs (specifically, solid models of production intent geometry) too early in the cycle. Loew argues that the industry needs to get back to the process of having disciplined engineers and machine/system architects drive the conceptual development right from the start and only add detailed CAD when appropriate. "My teams use 3D CAD early, but we are not creating 'product geometry' and certainly not committing to a product structure before it is time," he explained.

Loew is also concerned about the CAD industry's push for greater of ease-of-use, making it even simpler for engineering teams to get to elaborate geometry faster and earlier in the process. "My gripe is that in many organizations, the product development process STARTS with the creation of solid models that can very quickly appear to be production quality," he said.  "If the basic engineering at the product and system levels are not performed up-front, what business does anyone have generating solid models? Engineering belongs up-front -- detailed CAD generation belongs at the end of the product development process."

Premature solid model generation is replacing sound engineering practices. — Matthew Ian Loew

Others in the discussion took exception to this premise, sounding the argument that engineers, not just CAD jockeys, are now taking advantage of the easier-to-use, more accessible, and functionally-rich CAD tools to do  design and drafting as part of an integrated process. "Increasingly CAD users are engineers first, who happen to know how to draft as a skill," said Steven Weinberg, a mechanical engineer. "The design is embedded in the drafting in a way far more direct than it used to be.

Weinberg and several other commentators made the case for starting designs with a solid modeling approach, using that functionality of CAD to prove out the concept along with FEA, CFD, and a variety of other simulation tools. "CAD allows drafting and design to happen simultaneously, which is how things should be," Weinberg said. "There might be growing pains along the way, with both design and drafting suffering until we get it right, but I see the end result as both desirable."

What do you think about where CAD fits into the design process? Do you worry that detailed solid models are created too early in the process, causing teams to skip over critical engineering and mathematical work? Feel free to wade in on the discussion here and read Derek Cheng's post, which started the conversation.