The Occasional CAD


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No one likes a cad. They can be offensive, boorish, and troublesome. Many mechanical engineers in particular have no time for an ill-mannered cad – especially when the “cad” in question is a complex CAD system for 3-D modeling.

But in mechanical design as in life, the direct approach is often best. A growing wave of computer-aided design (CAD) products is putting direct 3-D design within reach of even the most CAD-averse mechanical engineers.

Direct modeling, also called history-free modeling, allows users to manipulate a 3-D model directly with a mouse or other input device using push–pull, drag-and-drop–style editing. It is a relatively new development compared with traditional parametric, or history-based, modeling, which builds geometry-based features one upon another to create an assembly—and which comes with steep learning curves and complex change procedures.

“Traditionally in the design workflow, mechanical engineers have been the decision-makers, and drafters have been the ones to document what the engineer specifies. It’s not uncommon in the world of parametric design for mechanical engineers not to touch CAD at all,” said Nancy Spurling Johnson, editor-in-chief of the top CAD industry magazine Cadalyst.  

Many of those engineers came through the ranks during the heyday of the traditional “CAD jockey,” the drafter-turned-technician who toiled the day away in the trenches of parametric-based mechanical design. Just as a symphonic percussionist’s job of keeping the beat is timed to the flick of the conductor’s baton, the CAD operator in many firms serves at the whim of engineers who have big ideas but limited understanding of CAD’s full complexity. Johnson said that attitude is beginning to change as engineering schools incorporate more CAD-related instruction in their curricula. “But that doesn’t affect all the people in the workforce now,” he says.

Post-meltdown economic circumstances may accelerate the pace of that change, as efficiency-minded companies look to reduce the cost and time of product development. With new direct-modeling software, these companies see the value in consolidating part of the CAD operator’s job into the duties of engineers, designers, and managers who need to create and edit 3-D models but aren’t CAD specialists.

Here are a few examples of the latest options on the market meant to appeal to the occasional CAD user looking for a direct modeler or an easier-to-use version of a parametric-based solution.

Direct Modelers

Creo Elements/Direct (formerly known as CoCreate, PTC, Needham, MA) cuts the time of design cycles by bringing more people into the 3-D design process. The system gives analysts the ability edit 3-D design data before analysis and to propose their design changes directly on the model. It allows tooling designers to create manufacturing jigs and fixtures and edit model data for NC and tooling design. The company touts the system’s interoperability among different CAD platforms.

KeyCreator (KubotekUSA, Marlborough, MA). The 2012 edition of this early direct modeler is said to provide better control and enhanced visualization, accuracy, and CAD file interoperability. The system includes three integrated add-on modules including a 2-3 axis NC milling function, CAD validation, and comparison capabilities and multiphysics simulation software.

SpaceClaim Engineer 2012+ (SpaceClaim, Concord, MA) was released in October 2012 for applications in manufacturing, simulation, concept development, and mesh remodeling. Enhancements to this version of SpaceClaim are intended to help “all engineers work more effectively in 3-D, without the high cost and complexity of traditional CAD,” the company states.

Hybrid Approaches

Inventor Fusion Technology (Autodesk, San Francisco, CA) The makers of AutoCAD are rolling out what they tout as a “best of both worlds” hybrid of direct and parametric workflows in a single digital model created in Autodesk Inventor. Inventor Fusion permits direct design changes and manipulation of complex shapes without altering the underlying parametric history

SolidEdge (Siemens PLM, Plano, TX), a core component of the Siemens’ Velocity Series portfolio, uses synchronous technology for accelerated design, faster changes, and improved imported reuse. Stated strengths include superior part and assembly modeling, drafting, transparent data management, and built-in finite element analysis.

Michael MacRae is an independent writer.

It’s not uncommon in the world of parametric design for mechanical engineers not to touch CAD at all.

Nancy Spurling Johnson, editor-in-chief, Cadalyst

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December 2012

by 12/17/2012 13:15:25