Low-cost CAD delivers high-priced features

June 5, 2003
In previous versions, Alibre Design was a capable but still emerging CAD program. The recently released Version 6 at $695 appears more complete thanks to improvements in sketching, modeling, and drafting, and the addition of a sheet-metal design function.

Sheet-metal designs begin with a sketch. A Flat Tab tool creates base stock. Users sketch shapes turn them into cutouts, holes, and dimples, which are added through simple dialog boxes. The dimple tool, for example, uses standard terms, such as punch and die radius, yet has powerful options, such as rounding profile corners on dimples.


After applying colors, materials, patterns, environments and other properties, users can hit an Editors tab and tweak the effect each property has on the model.


Picking the VisualMill command moves the current design file into the CAM program. This is one of the easiest CAM programs available. It has a user interface similar to Alibre Design and a similar history tree, this one showing milling operations.


Users determine mesh density in DesignCheck by positioning the slider bar on a Create Mesh dialog box.

In addition, the developer has added Alibre Design Professional for $995. It builds on the previous program with a series of modules for rendering, engineering analysis, machining, and a huge parts library.

Both include Alibre Assistant, an online mentor who shows how the software works through real-time collaborative capabilities in the software. For example, if you can't figure out how to build a formula to drive a sketch, the assistant can help. This Web-based personalized training and support is unique to Alibre Design and available at no extra cost.

The Assistant is usually new users' first exposure to the program's collaboration tools, which are so seamless, online users may not realize they are "collaborating." They let users "meet" in a virtual 3D space to communicate design ideas instead of just passing models back and forth in different formats and never really having any idea what changes were discussed. Because the software is a full 3D parametric solid modeler, users can make design changes during their online sessions just like any traditional CAD system. Each session has a leader who controls the session, and team participants who pass a "baton" between each other, essentially granting permission to make changes to the extend that their access rights allow. The latest additions to both programs deserve closer looks.

One improvement to sketching includes the capability to create B-Splines by Control Points. This tool, along with the existing B-Spline by Interpolation Points, gives the software more ways to create splines than some high-cost CAD systems. The Modify B-Spline command is quite powerful. For example, a curve created by one technique, say control points, can be edited by interpolation points. The command also includes tools to add and delete unnecessary points. But the most interesting option is the ability to specify the slope of a point by entering a weight and angle. In addition, the software now imports and exports splines.

Analyze Sketch, another enhancement, checks for five frequent sketch problems: disjointed end points, open loops, overlapping geometry, self-intersections, and degenerate geometry. Click the Analyze button and the software lists problems it finds in a dialog box while also displaying the problem areas. Users may heal the problems with a single click. Healing is useful when dealing with imported drawings in DXF and DWG formats because they frequently contain the listed errors.

Other new modeling tools create helical bosses and cuts. The software also creates 3D threaded holes.

The software has improved patterning and mirroring tools on feature and part level, making it easier and quicker to build assemblies. New algorithms in V6.0 open parts and assemblies faster, thanks to "light" parts. These are just visual representations of the real parts. When it's necessary to edit the parts, the software loads detailed geometry and parametric relationships. Tests show this cuts 50% off assembly operations.

A Catalog feature saves sketches and geometry sections for reuse. This is a big plus, especially for complex sketches that take hours to create and parameterize, and will be reused.

Defining and controlling design parameters through Excel spreadsheets is another big addition. After installing a plug-in in Excel, users select the file they wish to connect to the spreadsheet. Then changing a value in Excel updates the model. Driving designs by spreadsheet lets users store design information and quickly make iterative changes to generate variations, as in a family of parts.

The Professional version of the software adds tools for sheet-metal design and add-ons for photorealistic rendering, stress analysis, milling, and a part library. The Add-on Manager lets users determine which applications to load.

Sheet-metal design features include flanges, fillets, and chamfers. They work like this: After selecting the flange tool, for example, users need only select an edge and the software creates a flange on it. Flange length can be changed by keying in a new value or "dragging" it with the mouse. Flanges can be rectangular or rounded, and users can adjust where it sits on the edge. When adding flanges, users can apply K-factors or specify an unfold length. Users can also enter any angle, so 45° flanges are possible. In fact, a single pick rotates a flange 180° to create a hem, a technique not found in other MCAD programs. In addition, common parameters such as stock thickness, bend radius, and K-factors are stored as variables so they can be modified and easily used in an equation editor.When it's time to present designs, a photorenderer based on technology from LightWork Design in the U.K. (www.lightworkdesign.com), can dress them up. This function loads the current model and renders it with the current settings. Users can drag colors, materials, and patterns from a library.

Available background and foreground scenery includes furnished rooms. Users can add lighting, such as Clear Sky or Sun to illuminate scenes without taking the time to manually set up lights. Users who want more control can add and position white and colored lights. Similar features are available in Alibre Design for an extra $100 ($795 total).

Because stress analysis in the early design phase is gaining importance in engineering, the developer provides DesignCheck from Algor Inc., Pittsburgh (www.algor.com), in the Professional version. It's an FEA program that provides simulations without requiring analysis expertise of users.

The Create Mesh tool solves one of the biggest headaches in FEA -- creating accurate meshes. A simple matter of repositioning a slider changes mesh density. Specific areas can also be remeshed. After transferring models to an FEA Editor, users apply what Algor calls an FEA object, such as a force, moment, or boundary element. Adding an element such as a force calls for specifying its magnitude and direction. Users simply run the analysis and view results. HTML-based reports are easily shared with others by e-mail.

The Professional version also includes VisualMill, a CAM program from MecSoft. A Stock command tells the program to add an appropriately sized piece, based on the dimensions of the imported part. Cutting tools are selected or created through a graphical dialog box, feeds and speeds are typed in, and the software simulates the milling.

The tree displays all parameters for the operation. Should users wish to change a tool or its speed, for example, this is easily done with a double-click. Users can also assign parallel finishing, 2D profile machining, and drilling operations. More than 50 integrated postprocessors are available to create the NC code to manufacture the part.

Alibre Design 6.0 seems to be a price-performance leader in MCAD while Alibre Design Professional delivers value in visualization, engineering, manufacturing, and standard-component selection. What's more, the professional version gets an upgrade later this year that better integrates the previously mentioned modules. And both packages will receive surfacing features.

The two CAD programs come from Alibre Inc., 1701 N. Greenville Ave., Suite 702, Richardson, TX 75081, (972) 671-8492, (www.alibre.com)
-- Joe Greco

Mr. Greco, a consultant and CAD reviewer, lives near Scottsdale, Ariz.

About the Author

Paul Dvorak

Paul Dvorak - Senior Editor
21 years of service. BS Mechanical Engineering, BS Secondary Education, Cleveland State University. Work experience: Highschool mathematics and physics teacher; design engineer, Primary editor for CAD/CAM technology. He isno longer with Machine Design.

Email: [email protected]


Paul Dvorak - Senior Editor
21 years of service. BS Mechanical Engineering, BS Secondary Education, Cleveland State University. Work experience: Highschool mathematics and physics teacher; design engineer, U.S. Air Force. Primary editor for CAD/CAM technology. He isno longer with Machine Design.


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