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By Matt Lombard, Apr 3, 2012
For decades CAD salesmen have been promising to do away with 2D drawings, and to remove barriers to collaboration. But with each passing year, we tend instead to see more roadblocks to communication and collaboration between users of different CAD software. It is clear that real interoperability solutions are not going to come from the big CAD vendors.
There are interchange standards in place. For instance, ASME Y14.41-2003 defines methods for sharing PMI (product manufacturing information) through a practice called model based definition (MBD). The ANSI standard helps neutral data formats, such as STEP, carry more than just geometrical representations of products; it also includes GD&T (geometric dimensioning and tolerancing) information connected directly to the 3D model, as well as materials and surface finishes, and so on.
The use of these standards was pushed by the aero and auto industries, who have the most to worry about interchangeable files, but standards also benefit any enterprise living in a multi-CAD world and needs to share information with users of different CAD software.
Several geometry comparison tools on the market can already take advantage of PMI in translated files, and that’s what I look at in this review. Comparison tools are used to find expected and unexpected engineering changes between different versions of parts, and for validating accurate geometry and PMI data transfers between CAD software programs.
This article offers a brief summary of some of the CAD comparison tools that are available from companies other than the big CAD vendors.
Kubotek Compare is a $2,500 add-on to KeyCreator which I wrote about in more detail in a previous article. (See figure 1.) It can work as an add-on for KeyCreator or as part of the Kubotek Validation Suite be independent. CAD Compare enables you to compare parts and assemblies, as well as solids, surfaces, wireframe, point cloud, and mesh data. It uses geometry recognition to classify topology (like cylinders, planar faces, tori, and so on) and offers a face count for each type in each of the compared models.
Because KeyCreator includes a wide range of file formats it imports, Compare does not need files exported from the original system; you just read the files directly. This means it can compare a native Pro/Engineer file directly against an ACIS file. Compare also finds changes to PMI as text-based dimensions or as meta data.
Kubotek’s report writing sets it apart with visualizations and quantitative analyses of the differences. Plus, I find the idea of having a comparison tool connected to a direct editor compelling, for when I need to make changes to the imported data.
CapVidia has four products to help you work in your multi-CAD world (see figure 2):
CompareVidia (CompareWorks in SolidWorks) uses a parallel translation process to validate the results of imports into SolidWorks. For example, it reads Pro/E files directly, and then compares them to the translated files. The result is a “go/no go” situation: rather than telling you where the areas of difference are, it reports whether differences exist, followed by a report.
The Compare products work on the following formats: CATIA V4 (.model, .exp / up to 4.2.4), CATIA V5 (.CATPart, .CATProduct / up to R20), CATIA V5 PMI, Unigraphics (.prt / up to 18, NX6.0), Unigraphics PMI, Pro/E (up to Wildfire 4), Pro/E PMI, Inventor (up to 12), Parasolid (up to 20), ACIS, STEP, IGES (5.x - 6.x), VDA-FS, AutoForm (.af, .afm), STL, VRML, 3DTransVidia XML.
3DTransVidia (FormatWorks in SolidWorks) offers streamlined data import tools. Functions include PMI support, automatic and manual repair tools. While these products do not help with comparison or validation directly, they will help you get better quality imported data in the first place.
Figure 3: CCE’s EnSuite.
EnSuite ($3,495 per year) comes from CCE (a.k.a. CADCAM-E), a Michigan-based company in business centered on CAD translation, visualization, and product configurators since 1989. They specialize in migrating history tree information between various CAD systems. EnSuite is their multiCAD view/markup/measure/compare toolbox which is useful for any sort of shop that receives a variety of data types. See figure 3.
EnSuite makes use of a model points comparison in addition to face-to-face comparisons. It compares assemblies, and creates BOM data. It shows interference volumes, contact areas, and clearances between parts in an assembly.
EnSuite also allows you to induldge in multiCAD functionality that you may have never considered with a viewer for. For example, it allows you to insert a SolidWorks part into a Pro/Engineer assembly, position it, and then check for interferences.
Figure 4: ITI TranscenData’s CADIQ.
CADIQ automatically checks models for manufacturability or reuse problems, as well as unplanned changes in the model geometry arising from translation errors, misunderstood parametric relations, undocumented changes, and unanticipated assembly product structure changes. It also compares 3D PMI, including GD&T.
CADIQ can also be used in batch mode for processing large numbers of files, and use distributed computing for greater processing power. To enable the data originator to validate models being sent out, the front end installs as a plug-in with Catia V4/V5, Pro/E, NX, CADDS5, or SolidWorks. This assures that the translated geometry and PMI data is the same as the native geometry was.
In addition, CADIQ can be used as a component in DEXcenter, which automates data exchange through a Web interface. (See figure 5.) The support/specs area of the company’s Web site indicates that a standalone interface is available for customers who don’t have native systems. Standalone interfaces are available for the above systems, as well as for JT, STEP, IGES, Parasolid, and ACIS file formats.
Prices for CADIQ start at around $10 thousand, increasing substantially depending on configuration and implementation details.
Figure 6: Core Technologie’s 3D_Evolution Advanced Compare
In addition to straight comparisons of geometry, Advanced Compare also performs thickness analyses to find areas under or over a user-specified thinness/thickness value. When thin areas are isolated, a color scale indicates values. Sections are as easy to cut as dragging the cursor across a part.
Advanced Compare compares assemblies, including the individual part geometry and the overall assembly structure. It also detect interferences between parts in assemblies. The software creates HTML report files of the results.
It includes a compare utility that shows additions in one color, and subtractions in another. It performs certain manipulations with 3D CAD data, such as exploding views and sectioning views.
Licenses for AutoVue range from $300 for a single user license, to $1,000 for the SolidModel Professional edition.
In addition to geometry comparison, WorkNC compares the contents of layers within XDW files. This is intended for two purposes: comparing new files against existing ones while checking for changes to CAD data, and to check scans of machined parts against the original CAD model to ensure the machining was correct.
The Compare Geometry function within WorkNC shows the differences between parts as “Material To Add” and “Material To Remove;” the order of the original and modified part files can be switched. You can adjust the tolerance between surfaces, and selectively deactivate layers.
TurboCAD Drawing Compare is a $130 stand-alone application that compares 2D and 3D CAD data as well as PDF, vector, and raster image files. After a little investigation, the “3D” appears to mean a wireframe comparison done from a predetermined view. It supports DWG, DXF, SketchUp, TurboCAD, DoubleCAD, PDF, JPG, PNG and BMP formats. (See figure 9.)
OverCAD is a CAD software development house specializing in AutoCAD related software. The domain name is registered to a company in China, and is likely a single person writing some utilities. The website has very little information about the company, but they do have four products for sale, ranging from the $30 DWG DXF Converter for AutoCAD to the $280 DWG Compare for AutoCAD. In a bit of Chinese software piracy irony, OverCAD tools are readily downloadable from many sharing sites across the web.
ZWCAD is a Chinese 2D drafting package that includes a 2D compare utility. ZWCAD is the same company that purchased the former VX product and renamed it ZW3D.
Matt Lombard has written several books on SolidWorks, including the SolidWorks Bible series, a SolidWorks surfacing book, and a SolidWorks administration book. He has also written printed and video training materials for SolidWorks Corp., Solid Professor and Infinite Skills.
Most of Matt's design work has been in the plastics or "swoopy" shape medical and consumer products areas. He often develops products with inventors or acts as CAD overflow for larger organizations.
Matt's background is in manufacturing engineering, and product design for small electronic gadgets. He obtained a BSME from RIT in Rochester, NY, and prior to becoming an engineer was a musician in the US Navy.
Matt can be reached through his Dezignstuff blog.
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