Today’s CAD Packs a Lot

While the differences are in the details, nowadays, virtually all “small,” “medium,” and “large” computer-aided design (CAD) systems meet and exceed the basic requirements for designing new products. All can export and import design files from competitive CAD systems, as well as other engineering and business management software systems. All can run on desktop workstations, or have counterparts that do. All have add-on modules for advanced design, computer-aided manufacturing (CAM), computer-aided engineering (CAE) and finite element analysis (FEA), simulation, visualization, product data management (PDM) and product lifecycle management (PLM), and industry-specific design problems. Last, the cost of these CAD systems ranges from affordable — to affordable.

Here is an update about some basic requirements for CAD systems.

The CAD spectrum

First, an explanation. Low-end systems are typically single-user packages costing less than $5,000; mid-range systems generally cost less than $50,000 and support about 20 seats; and high-end systems cost tens of thousands of dollars, usually come with numerous add-on modules, and typically support multi-user global enterprises.

Given that universe of CAD products, here’s a sampling of what’s out there now. Note that low-end/low-price CAD does not necessarily mean elementary or functionally crippled CAD. For example, IntelliCAD is an AutoCAD clone; the two are almost the same. However, IntelliCAD comes from the not-for-profit organization IntelliCAD Technology Consortium (ITC; Portland, OR; www.intellicad.org) and AutoCAD comes from Autodesk (San Rafael, CA; www.autodesk.com). Second, AutoCAD 2009 costs about $4,000. ITC’s suggested price for IntelliCAD is $250, though some ITC members sell the software for $50 or less. Another low-priced deal in the CAD world is Rhino from Seattle-based Robert McNeel & Associates (www.mcneel.com). This full-fledged Microsoft Windows-based CAD system sells for about $1,000 ($195 for students and teachers).

At the low end of mid-market CAD is IronCAD from IronCAD, LLC (Atlanta, GA; www.ironcad.com). In the middle of mid-market systems are three CAD systems from think3 (West Chester, OH; www.think3.com). ThinkDesign Engineering is a mechanical CAD system, ThinkDesign Styling is for designing the style (shape) of parts, and ThinkDesign Tooling is for tool and die makers.

High-end CAD systems have it all. Users can mix-&-match add-on modules to meet specific company and industry needs, or the vendors will do that already through bundling. Pro/Engineer from Parametric Technology Corporation (PTC; Waltham, MA; www.ptc.com) comes in five basic flavors. The base system, Foundation XE, includes 3D solid modeling, 2D and 3D drawing documentation, surfacing (such as global modeling and warp surface modification), assembly modeling (including the ability to have a single bill of material (BOM) entry for multiple geometry states), sheet metal and weld modeling and documentation, mechanism design and design animation, design validation tools, data interoperability and import data repair, integrated web capabilities, and libraries of parts, features, and tools.

The high-end, Pro/Engineer Enterprise XE, includes all the features in Foundation XE, plus piping and cabling design, interactive surface design (complex surface creation, and G2 continuity), advanced assembly modeling capabilities (such as process planning, design for manufacturability, and 2D associative process sheets), advanced simulation capabilities (including mechanism dynamics, behavioral modeling, and structural and thermal simulation), collaborative project management, enterprise-level PDM, tolerance and sensitivity analysis, and intellectual property management. This version of Pro/Engineer has broad, associative capabilities for electrical, cabling, and piping design, as well as features to create tooling, NC tool paths, and inspection programs in parallel with product design work.

The crème de la crème in high-end CAD systems come from two vendors. Catia V6 from Dassault Systèmes (Auburn Hills, MI; www.3ds.com/V6), according to Dassault, is the company’s “next-generation platform for PLM 2.0.” Two more Dassault systems, Enovia for PLM and decision support, and Delmia for manufacturing engineering, help complete the PLM definition. The second system is NX, a CAD/CAM/CAE system from Siemens PLM Software (Plano, TX; www.plm.automation.siemens.com/en_us/). Technomatix is Siemen’s digital manufacturing system; Teamcenter, its PLM system.

CAD system attributes

This list of basic CAD features that follows is a composite of the aforementioned CAD systems. Note that advanced CAD features are not reserved just for high- or mid-range CAD systems. Innovative comes at the “low-end” as well.

Solids and surface modeling capabilities. Working in 2D and 3D requires some basic functions. Rhino at the low end supports 2D drafting, annotation, and illustration, as well as free-form 3D modeling. Designers can create all sorts of curves and surfaces—from points and lines, to polylines on mesh, to curves created from other objects (fillets, chamfers, offsets, and blends from two views, cross-section profiles, and contours on NURBS surfaces). A variety of functions are standard for editing curves, as well as for editing variety of surfaces (such as the Booleans union, difference, and intersection).

Bidirectional 2D/3D associative modeling. Hybrid modelers—CAD systems that have integrated 2D and 3D (solids) modeling techniques—are a given today. Associativity guarantees that modifications on a design represented as a 2D drawing or as a 3D solids model are automatically and correctly reflected in all associated 2D drawings and solids models. Associativity can also extend to auxiliary views, catalogs, text notes, GD&T, and BOM. For instance, IronCAD automatically extracts designated part properties into a fully editable table on the drawing. Once created, changes made to the BOM on the drawing automatically appear in the 3D model. This bidirectional editing capability speeds up the drawing creation process, while ensuring proper synchronization.

Parametric, explicit, or both. History-based parametrics and direct (explicit) geometry manipulation are the two primary methods of 3D modeling. Both have advantages and disadvantages. Pro/Engineer is parametric based (hence the “P” in “PTC”). IronCAD combines the two methods. The synchronous technology (ST) found in NX removes the linear dependency of geometries found in parametric modeling by capturing modeling knowledge on-the-fly. ST lets designers make on-the-fly (a.k.a., ad hoc) changes to those models. According to Siemens PLM, ST makes designing up to 100 times faster, especially with large, complex models, and it improves multi-CAD reuse.

User interface. The aim is to increase ease-of-use in 2D drawing and 3D modeling, editing, viewing, animating, and everything else to do with CAx. The new user interface in AutoCAD 2009, the “ribbon” interface, is similar to that in the latest version of Microsoft Office Suite. The interface groups commands by customer tasks rather than by a command hierarchy created years ago. These groups change as the designer’s tasks change, thereby reducing the number of steps to reach a command.

Another approach is in Catia V6. The user interface is lifelike, interactive, like a video game. A traffic light (red, yellow, green) indicates whether more information is available. A turntable-like display helps users navigate to that information. Double clicking a design causes the turntable to display major subsections of that design, such as parts, subassemblies, and schematics. Additional double-clicks on a subsection drills down to additional information, which spins off into separate turntables.

Design automation. Global Shape Modeling (GSM3) in think3 CAD systems makes design modifications easy while it maintains the original design concept. As a designer morphs, warps, or otherwise modifies a design, GSM captures the initial targets for the design (points, curves, or specific part highlights) and then automatically calculates the detailed solid and surface design math, including all technical and engineering requirements. From that it creates the modified design while preserving the original design intent. GSM works in real time so designers can modify their designs without having to constantly rebuild those designs. GSM operates on specific areas in a design or to the entire design.

Smart design automation. Several CAD packages use “smart objects” to capture, reuse, and share model designs and design steps. Designers merely drag-&-drop these objects from pre-built or in-house created parts catalogs and libraries, such as Inventor’s iPart, to a new or existing part design or scene. The smart object’s properties are then automatically added to that design or scene. Smart objects ensure design consistency and compliance to a company’s design standards, fewer errors, and faster design cycles.

Analysis. Basic CAE and FEA tools are often included in CAD systems. More advanced FEA comes in additional modules. The design analysis tools in Rhino range from determining the simple—length, angle, radius, area centroid and moments, volume (centroid and moments), and so on—on up to the more complex—hydrostatics, geometric continuity, deviation, and working surface analysis viewport modes (draft angle, zebra stripe, color-coded feedback, Gaussian and mean, curvatures, and minimum or maximum radius of curvature).

Inventor includes tools that help verify that products can in fact be assembled by letting designers insert and position new components in an assembly and add constraints that define fixed and moving components. Inventor can graphically display mechanical interferences and overlapping material, as well as test for potential collisions between moving parts. Color feedback tells designers when critical design parameters are exceeded, such as length, distance, angle, area, volume, and mass.

Simulation and visualization. Most CAD packages, even at the low end, offer real-time photorendering, animation, videos, flythroughs, and the like. IronCAD, for example, includes ray tracing, shadows, texture/bump/decal mapping, and anti-aliasing for creating photorealistic images. Any number of directional spotlights can also be created. Special visual effects include fog, glow, reflections, transparency, gels, and a range of lighting from direct sunlight to deep shadow.

Manufacturing capability. Autodesk Inventor can generate production-ready drawings for manufacturing and outside suppliers. Designers can pick specific views for a drawing, including front, side, ISO, detail, section, and auxiliary views, as well as overlay drawing views to illustrate various stages of assembly. Inventor also lets designers hide lines at the component level. Inventor will automatically dimension drawings, including isometric view dimensions. For BOMs, Inventor will automatically number items and define materials for virtual components (such as glue and paint). Other documentation produced by Inventor include technical illustrations, process sheets, training materials, parts manuals, assembly instruction sheets, and training videos.

Industry-specific CAD. Many CAD vendors offer various “flavors” of their products. AutoCAD, for example, is the centerpiece to an array of vertical applications from Autodesk. AutoCAD Civil 3D generates surveying, design, analysis, and construction documentation for civil engineers. AutoCAD Electrical includes symbol libraries and workflows suited to electrical engineering and control systems. AutoCAD Mechanical includes standards-based symbol libraries, engineering calculators, and workflows for mechanical engineering. AutoCAD Architecture is for, natch, architects, AutoCAD MEP is for mechanical, electrical, and plumbing businesses, while AutoCAD P&ID is for creating, modifying, and  managing piping and instrumentation diagrams. AutoCAD Map 3D combines CAD and geospatial information systems.

Both Dassault’s Catia and Siemens PLM’s NX have dozens of modules to address specific design tasks and industry design problems—enough to fill a hefty catalog (dead-tree version). Catia modules, to name just a few, cover mechanical part and composite design all the way to manufacturing analysis, electrical harness design to documentation and printed circuit board design, automatic drafting for cast and forged parts to functional tolerancing and annotation review, and shape design and styling to NC machining. Likewise, NX is available for mechanical, package, and electromechanical systems design, and for industrial design and styling. All the modules and products are integrated with the base CAD system and the other product lines of the respective companies.

Data exchange and file healing. Most CAD systems “play nice” with other systems by supporting most, if not all, major CAD file formats, such as DXF, DRAWING, IGES, JT, STEP, and VRML; STL for supporting 3D digitizing arms, scanners, and printers; and various other industry-standard formats such as PDF and XML. Most CAD systems, through converters, gateways, or simply import/export features directly support third-party CAD systems based on different modeling kernels (such as PTC’s Granite, Siemens PLM Software’s Parasolid, and Dassault Systèmes ACIS).

The data conversion and import is hardly perfect. Many CAD systems include functions to “heal” such files before a designer works on them.

Speed. Several aspects of a CAD system make it “speedy.” According to PTC, these aspects include modeling capabilities, depth of functionality, the allocation of computer memory (especially when displaying designs and building assemblies), the accuracy and breadth of features contained in the modeling kernel, the user interface, and the native data file (size and storage). IronCAD version 10, for example, takes advantage of the latest OpenGL and Direct3D graphics drivers to speed the graphical rendering, 3D rotation, and camera selection of large assemblies. The software can create 2D views from 3D models up to 10 times faster than previous releases.

PDM/PLM. Often, PDM comes as a proprietary add-on to the base system. However, Autodesk Vault, a PDM system, comes with Inventor. Extensive PDM is usually bundled in with the high-end (read expensive) systems, namely PLM, such as Teamcenter from Siemens and Enovia from Dassault.