Why moving to solids makes sense

The automated, ultrasonic railroad-wheel testing station was built by Fraunhofer TEG in Germany using SolidWorks. The packaging study includes colorful models and line drawings, making it easy to recognize pneumatic and electric components, along with actuators and extruded structural beams.

Solid-modeling software has been commercially available for almost 30 years, yet only about 25% of the engineering community uses it. That's puzzling because solid modeling is the best way to automate the creation of 2D production drawings and it allows an unprecedented degree of PC-based design visualization, trouble-shooting, and modification. New-product-development time frames can be dramatically compressed, costs and scrap reduced, and to boot, designers have more fun. So why has the migration taken so long?

Early on, it was fair to question the move from 2D to 3D because the degree to which design departments actually saw benefits varied from system to system. And in the early days, the primary benefit of 3D was improved visualization, which is why many engineers believed early systems were merely for making "pretty pictures." Hence, few made the transition.

This is now
If a picture is worth a thousand words, then a 3D model must be worth a thousand drawings. Seeing a colorful 3D image of a product certainly conveys more information and understanding than a flat drawing. But better visualization is just one in a long list of advantages gained from embracing 3D CAD.

Today's 3D systems are more capable, affordable, and easier to use, thanks to technologies like powerful low-cost computers and Windows. Those who use it today see it as nothing less than mission critical. What's more, the return on investment for 3D CAD technology is more tangible than it was 15 years ago.

Three-dimensional CAD systems successfully address challenges encountered every day when working solely in 2D. Take communicating design intent, for example, a CAD system's key function. Working only in 2D, engineers and manufacturing personnel have to interpret or visualize flat drawings as 3D parts or assemblies. Try imagining the lead image in this article as a 2D drawing. That could give you a headache. It's not hard to see how misinterpreting 2D drawings can lead to rework and delays. Three-dimensional CAD, however, eliminates most drawing misinterpretations. Working in 3D also lets users see and fix tolerance problems. They can check their work by assembling components on screen. When parts interfere, visual cues (such as color changes) can identify the intersecting volumes. With 2D assemblies, on the other hand, judging how well parts fit and operate, borders on guesswork. Fit and tolerance problems can go undetected until late in a design cycle -- often after cutting metal.

The simple planetary gear train can be put in motion to check for correct rotations and then moved to larger more complex assemblies. The feature provides only kinematic studies, but is impossible in a 2D package.

Other pluses include:

Handling large, complex assemblies of moving parts. It is more instructive in 3D. Most solid-modeling systems work with motion-analysis programs so users can see proposed designs in action. When the motion study shows that a particular movement, such as an arm extension, is insufficient, the digital assembly can be modified to correct the shortcoming. Performing similar studies working solely in 2D can be tedious, labor-intensive, and slow. Drawing checkers alone can spend countless hours pouring over drawings testing fit and tolerance dimensions. And this is compounded as multiple related drawings often need to be checked concurrently.

Simply put, designing in 3D is the best way to generate drawings quickly. Most 3D systems produce drawings in seconds once a design is complete. Users identify top, front, and side views, and cross sections, and the CAD system automatically generates the views and applies the dimensions. Leveraging 3D technology, documentation, publication, and marketing support improves significantly. Graphics, drawings, and exploded assembly illustrations can be generated easily from the original solid model.Contrast this with manually creating the same drawings in 2D. This inevitably requires mental gymnastics to correctly envision each view. And drawing multiple views, such as isometric, exploded assemblies, details, and sections, is additional work because redrawings are made line by line.

A single menu pick transfers SolidWorks models into CosmosXpress, an analysis tool that comes with the solid modeler. It lets designers see whether or not a part taking shape is sized to handle anticipated loads.

Design changes are now quick and easy. This is where 3D systems really pay off. For example, change a dimension in a 3D assembly and it propagates throughout all other components and related drawings. What once took several hours in manual 2D operations now takes seconds in the 3D world.

It's easier to configure derivative products and product families. Solid-modeling systems often include spreadsheets to hold the driving equations and key dimensions that let users generate larger or smaller versions of the original part or assembly. It is more difficult in 2D to efficiently develop variations of complex products and assemblies. Product variants of different sizes, dimensions, weights, or capacities must be redrawn separately.

More CAD data gets used downstream. Almost every company operation that uses information from the design department functions more efficiently with 3D data. Analysts perform simulations on 3D models, manufacturers generate toolpaths on them, and the marketing department can use photorealistic images in brochures and on the company Web site. Doing this in 2D means massaging information into usable forms for each operation.

Models allow more thorough simulations. A 3D model lets analysts check a part for many loads and physical conditions. And fluid-flow simulations reveal more about what goes on inside products than physical testing ever could. In 2D workflows, analysts may limit stress studies to looking at estimates from hand calculations and one or two load conditions.

Manufacturing cycles shorten. These operations work well with complete 3D solid models because manufacturers expect to produce every detail in the design. A 3D model eliminates the need to recreate or manipulate design data. Two-dimensional design data, on the other hand, must be recreated and manipulated several times to support operations, such as prototyping, stereolithography, manufacturing, fabrication, and assembly. This adds time to manufacturing cycles and each data recreation is likely to introduce errors. Clearly, 3D technology is now mainstream. Over a hundreds thousands manufacturers have adopted it worldwide, and others are soon to follow. In the past several years we have seen solid-modeling tools become easy to use, powerful, and affordable. The overwhelming majority of engineering curricula worldwide has made solids-based design a core course. And a broad range of tightly integrated complementary software solutions, such as mold design, optical design, and tolerance analysis, are now available to let today's engineers develop better products faster.

While most 3D systems resolve 2D-specific design challenges, not all solid-modeling systems are created equal, nor are all migration paths simple and straightforward. Capabilities, utility, ease of migration, and ROI vary from system to system. All this makes selecting the right package to meet a company's needs a daunting task.

But it need not be. By asking a few questions, CAD shoppers can more readily compare systems. For example:

Is it important to design stylish products? Will users create complex models, surfaces, and shapes? If so, the 3D package should handle curves, blends, fillets, and unique shapes better than the existing 2D system does. Some 3D systems do this better than others.

Do you find initiating one change kicks off several others? If so, ask about bidirectional associativity and parametric design capability. These ensure that elements of a design, such as assembly and component models, drawings, and bills-of-materials, are linked and changes flow from wherever they are made. Likewise, parametric design can maximize the benefits of 3D. A 3D package should store all features and dimensions as design parameters, so designers can rapidly change the design simply by typing in different dimensions.

Does the design involve large assemblies? Design departments should evaluate their large-assembly needs against the capabilities and limitations of different 3D systems. Can the candidate handle thousands of parts? How are assemblies managed? Does the system have tools for design evaluation, such as interference checking and collision detection?

What's the availability of add-on programs, such as analysis, product-data management, and computer-aided manufacturing? Are specialty applications available, such as sheet-metal tools, optical-design applications, and tolerance-analysis software? One indicator of a program's usefulness is the number of partners the CAD system attracts, their reputations, and the degree of integration provided. This latter point suggests little integration means users will have to manually export and import models from one system to another, which may involve model repairs. Well-integrated systems move CAD models with a single menu selection.

How does the system access and use legacy data? Does it provide data-translation formats and tools for converting 2D data into 3D models? Ideally, managing legacy data should be almost as easy as managing drawings and models created in the 3D CAD system.

Does the package include sufficient capabilities for visualization, design evaluation, and animation? Eye-catching models are useful to marketing departments, as well as pitching design ideas to higher ups. Animations show how assemblies work and possibly show production people how products assemble. The latter feature also reduces prototyping costs.

What tutorials are available? Believe it or not, a 3D system should be easier to use and require less training than a 2D package. Consider whether it is intuitive, requires few steps or menu picks, automates repetitive tasks, and provides an open API for customizing functions. Designers should be able to use a solid modeler after a few days of training and become proficient in weeks, not months.

Does the package work with desktop office tools such as Microsoft Word, Excel, and PowerPoint? Can the package export design data directly into documents, presentations, and spreadsheets?

Does the CAD vendor provide a reliable means for calculating an ROI?

Is the company financially secure and its technology considered a design leader? A company's financial health, user base, and vision indicate its commitment and customer support.

Does the package support import and export of common data formats, such as DWG, DXF, IGES, STL, and STEP? This is important for interacting with customers and vendors who use different systems.

How does the package create similar parts with different dimensions? This is critical for manufacturers that produce families of parts in varying sizes.

Does the package provide Web-based communication tools for sharing data with vendors and customers, and for collaborating with colleagues and partners?