Model Based Definitions

I am a recent convert to Model Based Definitions (MBD) as the best way to document a product and its specifications.  I am old enough to have learned drafting on a table with pencil and paper so I was a reluctant believer until we printed our first part on our new 3D printer.  This was the moment where the light bulb went off and I understood that MBD is the way forward.

With classical 2D drawings of 3D models, the 2D drawings is the control document with dimensions, notes, and all the details that are required to make the part.  With MBD, the part is what is controlled with all the dimensions and notes and details right on the 3D model.  The 3D model is now the control item.  Now with computer driven production like 3D printing or CNC, the 3D part is sent directly to the printer and produced.  Details like surface finish and other control items must be build directly into the model and having a great 2D drawing is basically irrelevant.

I am not suggesting that the 2D drawing has to go away.  Having a fully documented 3D model makes creating a 2D drawing a fairly straightforward operation but not a requirement.

I am finding the MBD process also makes the design more robust and takes less time to get completed.  Having fully detailed 3D models allows assemblies to be analyzed and optimized quicker and more fully than comparing a stack of 2D drawings.  Automated design optimization packages can also review tolerances and interferences automatically and report on issues at the click of a mouse button.

As budgets for new product engineering continue to be tightened, the draftsman position has all but disappeared and high cost engineering resources are being used to create 2D drawings.  As MBD becomes more widespread, this is a huge opportunity to reduce the costs of new product development.

MBD has been embraced by the aerospace, automotive and medical industries because of the risk in human life associated with mechanical design.  The ability to shorten the time to get products to market and reducing the development costs in these industries is also a huge competitive advantage.

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