The Proliferation of Solid Models

An overview of the benefits of solid models and why you should get on the band wagon.

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How many times have you received a 2-D drawing that was created from a 3-D model, only to then spend days recreating it in your CAD or CAM system? To me, all of the back and forth seems a little ridiculous. Engineers are designing parts or assemblies in 3-D CAD and then spending hours creating detailed 2-D drawings from the 3-D model.

The whole point of this column is to point out that we have yet to realize the true value of 3-D design data. We must encourage software developers and designers who are using the software to finish what they started. As an industry, we can always use more products that enhance our productivity

Nowadays, most of the CAD software packages let you embed Part Manufacturing Information (PMI) as part of the model. The attributes embedded in a 3-D model are tolerances, finishes, material type, notes, etc. Everything that would be on the 2-D drawing can be embedded in the 3-D model’s PMI. Just think about how much smarter and more productive your CAM system could be if it could leverage the PMI data.

The same thinking could be applied to the coordinate measuring machine. When it came time for inspection, you would eliminate print interpretation and human error. I can only imagine the productivity gains and reduced errors from having to keep up with only one file, especially when revisions came around.

When design engineers made the move from paper to CAD software in the early 1980s it was a tremendous productivity improvement on several accounts. It was just faster and easier to fix mistakes than drawing by hand and more importantly, designers could no longer just fudge the design with their pencil and slight of hand so the design looked good on paper, but kept those of us in the shop scratching our heads because the math didn’t work.

I got the best experience of my life working in an automotive tool and die shop where I got to see firsthand the next productivity enhancement CAD could offer—3-D surface modeling. One way to picture 3-D surface is as a free flowing skin—it does not have a thickness, but represents a topology. 3-D surfaces are very good for describing non-prismatic geometry, such as automotive body parts.

Prior to 3-D surfacing technology and the ability to generate CNC code to machine the surfaces, toolmakers had to use duplicator milling machines to trace a part that someone had made by hand to produce die or mold components. Needless to say, the duplicated parts were not very accurate, took tons of time to produce, and left us stoning for hours.

The next evolution in CAD was solid modeling, which is the ability to represent parts and assemblies as 3-D objects with your design software. 3-D models can combine 2-D geometry and free form 3-D surfaces for the best of all worlds. Solid modeling was very expensive and only used by a few very large innovative companies until the mid-90s when SolidWorks was founded.

The company’s vision was to put 3-D solid-based design software on every engineer’s desktop because if the company was successful, it would make the world a more efficient place—and it has. Virtually everyone who designs anything mechanical today does it in 3-D.

Who are the new innovators in CAD and CAM that are going to lead the next wave of productivity enhancements by allowing us to finally eliminate those 2-D drawings and give way to smart 3-D models?