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CAD For The Small, Medium, and Large

Price, breadth of features, and product lifecycle management are what mostly separate CAD systems in corporate eyes.
#Siemens #Intel #Carbon


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What makes a computer-aided design (CAD) package right for a small, medium, or large company? In a nutshell, explains David Cohn, independent CAD consultant and author in Bellingham, WA, small discrete product manufacturers need "capabilities, but they'll struggle with making a lesser tool do what they need because they can't afford a $50,000 seat of something. Medium-sized companies are also designing small, discrete parts or portions of larger assemblies. They need a tool that's going to do what they need. They probably need more seats, but they're still price sensitive." High-end CAD users, such as OEMs, are managing an entire process, from design and engineering to production and assembly, to shipping and warranty service. "It's not that [high-end CAD] software itself is stronger in a particular area," explains Cohn, "but the software can cover all the pieces. High-end software lets these companies manage the whole process, which is where product data and lifecycle management come in."


CAD for small companies

Small manufacturers—specifically third-tier suppliers—need something more than 2D CAD. Several solids modelers fill the 3D CAD niche "where everything is price sensitive," explains Cohn. There's AutoCAD from Autodesk (San Rafael, CA; autodesk.com) for about $4,000. Alibre Design from Alibre (Richardson, TX; alibre.com), starts at $197, but once other modules are added, can cost $2,000 or more. Some people are doing 2D CNC with TurboCAD from IMSI Design (Novato, CA; imsidesign.com). Ashlar-Vellum Graphite for 2D and Cobalt, Xenon, and Argon for 3D modeling from Ashlar-Vellum (Austin, TX; ashlar.com), starting at about $1,200, runs on both Windows and Mac OS. Rhino from McNeel North America (Seattle, WA; rhino3d.com), for about $1,000, is competent at body-in-white.

Let's pick one. AutoCAD used to be considered a "dumb" 2D CAD package. Over the years, says Cohn, Autodesk has migrated an "an extensive set" of shape- and surface-modeling tools into this package. Two years ago, Autodesk vastly improved AutoCAD's visualization capabilities and user interface. The improvements follow Marketing 101: Get AutoCAD users to upgrade to Autodesk solids modelers, such as Inventor. 

The latest release of AutoCAD, and its various industry-specific versions, introduces several new features. For starters, constraint-based parametric drawing. As with 3D modelers, designers can put some "native intelligence"—design intent—into AutoCAD drawings by defining dimensions, mathematical equations, and other relationships between objects. For example, a designer can specify a line remain tangent to a circle. Parametric functionality speeds drawing creation and revisions by automatically maintaining these relationships. AutoCAD's parametric constraints also work in dynamic block definitions, which save time when creating new geometries for each model variation.

Designers using new free-form design tools can create almost any kind of shape by pushing and pulling faces, edges, and vertices. They can also create simple mesh primitives, specify the tessellation value for each primitive, make the meshes smoother, and convert the meshes to solid objects. Conversely, designers can convert existing 3D solids and surfaces into mesh objects. Along the way, designers can split and extrude meshes into objects.

The vector resolution for PDF export in AutoCAD 2010 is higher. PDF text output is searchable and visually better because Truetype fonts can be embedded, and the program can output single or multi-sheet PDF files. On the import side, designers can use a PDF file to underlay a drawing. In a more substantive vein, AutoCAD can produce physical 3D models simply by connecting it to on-demand 3D printing services or personal 3D printers.

One caveat: AutoCAD 2010 has a new DWG file format. While this version can open design files from previous AutoCAD versions, users will have to remember to save files to the older AutoCAD versions when collaborating with users of those older AutoCAD programs.


CAD for medium companies

According to Cohn, mid-range CAD goes for $5,000 to $10,000 a seat, depending on what's included. Typical mid-range CAD systems include Inventor from Autodesk, Solid Edge from Siemens PLM Software (Plano, TX; plm.automation.siemens.com/en_us/products/velocity/solidedge/index.shtml), and SolidWorks from Dassault Systèmes SolidWorks Corp. (Concord, MA; solidworks.com). When cornered, Cohn explains that in mid-range modelers, "there's no clear winner between Inventor, Solid Edge, SolidWorks. Plus, you've got Alibre nipping at their heels, IronCAD from IronCAD (Atlanta, GA; ironcad.com), think3 from think3 Inc. (Cincinnati, OH)—which is strong in Europe—and a whole bunch of other mid-range CAD systems. They can't differentiate themselves on their ability to model geometry because geometry modeling has become a commodity."

That's not to gloss over the individual strengths of these CAD packages. For example, points out Cohn, "a couple of years ago, if you were into assembly lines and welded fixtures and things, you'd go with Inventor. If you were designing in rolled metal or stamped metal, you'd go with Solid Edge. And if you were working in injection molded plastic and consumer esthetics, you'd go with SolidWorks." All of these CAD systems have grown over the years.

Take a look at the SolidWorks 2010 product line, a family of solids modelers that include a variety of mechanical CAD, design validation, PDM, and collaboration tools. Basic functionality includes freeform surfacing tools, the ability to create stylish curve-continuous (C2) surfaces, bills of materials (BOMs) that automatically update with design changes, and the ability to preserve design intent and make changes to imported non-SolidWorks CAD data. Frequently used parts, features, templates, sketches, and so on can be stored in a "Design Library." These are available as drag-'n'-drop items for new designs. Built-in data translators for all major (and some minor) CAD formats let designers exchange CAD data with other software systems. With SolidWorks Premium, the company's flagship, users get all the functionality of the "standard" package, plus they can work from product concept to virtual prototype within the same program.

A new dimensioning tool in the 2010 version shows alternatives for placing dimensions. When necessary, the tool automatically rearranges the placement of existing dimensions. Simple mouse movements ("mouse gestures") now execute commands, reducing keyboard use or taskbar access for frequently used functions. Designers can now create opposite-hand ("mirrored") components as derived configurations of components in the design tree, while maintaining the position of these new components relative to the "seed" components.

SolidWorks 2010 offers much for sheet-metal designing, starting with simpler ways to create complex sheet-metal designs, including weldments and other sheet-metal parts. Designers can edit sheet-metal files before export as DXF or DWG files, such as deleting bend lines, the edges of countersunk holes, and other excess items. Complex sheet metal parts can consist of multiple sheet metal parts or a combination of sheet metal and weldment parts.

All the SolidWorks 3D CAD products come with SolidWorks SimulationXpress, a design validation/simulation program that tests virtual designs against real-world conditions. This tool goes beyond time-based simulation in that they can now be based on events, such as the completion of a machine task or the output from a sensor. The Premium product includes tolerance stack-up validation and tools for simulating assemblies, mechanical parts, and welded structures.

SolidWorks Sustainability software displays information regarding the carbon footprint, energy consumption, and air/water resources in a new design's product lifecycle. The software includes an environmental impact dashboard, customizable reports, and a tool to compare multiple design iterations for environmental concerns and find alternative materials based on those concerns.

Workgroup- and enterprise-wide PDM capabilities are covered by two other versions of SolidWorks. SolidWorks Enterprise PDM, for example, can automatically convert hundreds of manufacturing drawings into neutral formats for quoting, collaboration, and batch printing. It can also revise multiple part numbers within a single file by using configurations as unique part numbers. But now that's getting into high-end CAD.


CAD for large companies

NX from Siemens PLM and Catia from Dassault Systèmes (3ds.com/products/catia/welcome/) dominate high-end CAD. Next comes Pro/Engineer from Parametric Technology (PTC; Needham, MA; ptc.com). There are others. As a pure-CAD play, NX is probably as good as it gets. As with many of the other CAD systems mentioned, NX has additional modules for computer-aided engineering (CAE), computer-aided manufacturing (CAM), simulation, and so on. This suits large companies just fine because they rarely are looking for CAD alone.

NX 7.0, the latest version, includes enhancements to synchronous technology (ST), a feature Siemens introduced in 2008. ST combines constraint-driven designing with history-free modeling. ST improves NX's ability to work with geometry data from third-party CAD applications. New synchronous pattern capabilities further help designers work on legacy CAD models without having to understand the original creation approach. Also helping is that imported B-surfaces can be converted to rolling-ball blend faces for easier editing. On native or imported models, designers can assign chamfer properties to angled faces and resize them, adding offsets and angles, regardless of the feature history. In history-free mode, designers can move multiple-component faces in assemblies, and both section and edit models and features by changing the cross-section curves. Ultimately, these enhancements and tools make it easier to adapt new designs from older product models.

NX 7.0 introduces HD3D, a "dashboard" for displaying information about product development directly on 3D models. HD3D, short for High-Definition 3D, gives designers immediate, visual access to PLM data, such as project and release status, design changes, team responsibilities, material types, costs, and delivery status—data produced in a variety of forms, formats, and places by a multitude of software products from a multitude of vendors. HD3D displays information using color-codes, on-screen tags, and legends. Designers can flip through these displays and mouse-click for more details. HD3D replaces the mostly manual task of poring through and processing lists of attribute data, BOMs, and status reports, and then correlating those data to 3D product models.

Incidentally, as of last June, NX can run natively on Mac OS X from Apple Inc. (Cupertino, CA; apple.com) on 64-bit Intel-based Mac computers. This is in addition to operating on Windows, UNIX, and Linux, and regardless of operating environment (single or heterogeneous). The Mac OS X version of NX also supports Teamcenter, Siemen's PLM system, through a thin client based on Apple's Safari web browser.


So what's a company to do?

When asked about selecting a CAD system, the first question Cohn asks companies is: What are you going to do? Says Cohn, "If you pry and dig deep enough, you find out what their biggest design issues are. Then you can usually find one program that is better than the others at the particular things they're looking for. Then it's a matter of file formats and who the company wants to work with."