MCAD Modeling Methods: Mechanical CAD Today30 Sep, 2004 By: Don LaCourse Cadalyst
Software innovations accelerate the mechanical design process.
When I was asked to write about the state of the mechanical CAD industry, I was more than a little reluctant to parade the usual charts and graphs that show statistics and market growth for the well-known CAD developers. Such reporting is better left to industry analysts such as Daratech (www.daratech.com), who do it so well and so often. However, I did check in with many mechanical CAD developers, and all report double-digit percentage increases in sales from this time last year. There is a clear consensus that the economy has completed its rebound and is on the rise.
Figure 1. The Object Editor in VX Corps VX CAD/CAM (www.vx.com) provides a quick and easy way to perform many common editing tasks. Simply move the cursor over an object to highlight it and right-click to display a popup menu that contains context sensitive commands. Pick filters are provided for complex displays to filter the object type to highlight. You can also double-click on an object such as a sketch to activate it for editing. Context sensitivity extends to menus managers and options forms.
If you follow my columns, you know that I write from the perspective of those using and managing the mechanical CAD application. Don't get me wrong—charts and graphs serve a very important purpose, but you don't need them to know that mechanical CAD is alive, well, and better than ever. Just look at the applications today and remember what it was like even a few short years ago. Here are some things that clearly make mechanical CAD what it is today—I bet you're already taking them for granted.
Object-based Context SensitivityNot too long ago, you wasted a lot of time locating commands buried deep within the menu hierarchy. You needed to know and understand what menu selection to make to perform a given task, such as applying draft to a face. Today, object editing removes the guesswork by displaying only the applicable commands when you select or highlight an object such as Offset, Draft, and Extend when you select a face.
Figure 2. SolidWorks (www.solidworks.com) employs what the company refers to as Heads-Up interactions that speed user throughput. The most apparent Heads-Up component is context-sensitive Property Managers. These replace the Feature Manager Design Tree automatically when appropriate and let you change properties or options of objects in SolidWorks. Property Managers anticipate your needs and supply a common interface to make changes.
This object-based context sensitivity is now widely used in mouse-driven pop-up menus, pull-down menus, and all dialog boxes. Today's mechanical CAD applications understand what you need at any given time and even try to anticipate what you will or may need soon. In many instances, you can bypass the menu structure, saving precious design time.
Integrated Design EnvironmentsMechanical CAD is defined today by its ability to deliver integrated and highly specialized design environments that were once the sole domain of third-party applications (figure 3). Designers are fortunate to have the most common tasks almost completely automated. For mold designers, defining complex parting lines, separations for core and cavity regions, and slide, insert, and cooling designs take a fraction of the time previously required. That's not to mention complete mold base assemblies that you can create on-the-fly from built-in parametric libraries.
Roots of the Problem
For sheet-metal designers, today's mechanical CAD applications save enormous amounts of time by providing a command for virtually every common sheet-metal feature, including flanges, dimples, louvers, and corners. What previously took ten commands and 45 minutes to model now takes one command and five minutes (figure 4). Productivity is increased tenfold. Such super features aren't exclusive to sheet-metal design. You can also find them for injection-molded part design.
Other sheet-metal tasks are also automated or integrated, such as folding and unfolding for flat-pattern creation and K-factor compensation (figure 5). K-factor is a ratio based on the expansion and compression properties for a given material. It's used to define the location of the neutral axis within the thickness of the sheet metal for bending.
Figure 3. Dassault Systèmes CATIA Mold Tooling Design (www.3ds.com) works cooperatively with other CATIA applications, such as those for part design assembly design digital mockup drawing generation and manufacturing to establish an environment for creating simulating and machining tools.
Self-Analysis and Topology HealingI've written extensively on the subject of data exchange and how data loss and topology errors are commonly introduced during data translation. This thorn in the side of 3D CAD has caused the loss of immeasurable amounts of time and money. Today, mechanical CAD is further defined by its ability to meet this problem head on and in many cases overcome it.
Figure 4. Super features in Solid Edge from UGS (www.solid edge.com) can create a complete, multi-operation mounting cooling vent with a single command. That includes process operations such as rounds and draft. Vents are found in almost any consumer or office product that produces heat.
Mechanical CAD applications provide the tools needed to analyze and heal the most common topology problems that can stop design and development in its tracks. I'm talking about missing surfaces, edge mismatches, cracks, and gaps—just to name a few. Many applications even perform topology healing automatically during imports.
Figure 5. Autodesk Inventor (www.autodesk.com) provides integrated sheet-metal design tools as an extension of its part modeling feature set. Such a complete toolset, including material styles, sheet-metal specific features, and unfolding and exporting capabilities, gives sheet-metal designers the tools they need to get their job done.