Issue: Volume: 22 Issue: 11 (November1999)

Reviews: Autodesks Inventor

Evan Yares

Three years ago, Autodesk decided to write the next-generation CAD program--one so powerful and well designed that it could ultimately win the business of the most demanding users: companies that make airplanes and automobiles. Though Autodesk hasn`t actually stated that this was its goal when it set out to develop Inventor, a careful look at the new Autodesk mechanical CAD program (previously code-named Rubicon), seems to confirm that intent.
Autodesk's Inventor allows users to work in very large assemblies, such as this helicopter rotary system. (IMAGE: Mathew Simmonds.)

On the surface, Inventor`s specifications are similar to those of its major competitors: Solid Works, Solid Edge, and Pro/Engineer. It runs on Windows NT, creates feature-based solid models, assemblies, and associative drawings, uses the ACIS modeling kernel from Spatial Technology, and sells for $4995. But looking past the surface, you find a program that, despite its first-release limitations, is destined to be a major player in the mechanical CAD market.

The factors that define a great CAD program are fairly simple. It must be easy to learn and use, so that the average person can become productive with little formal training. It must be powerful enough to do whatever a user wants it to. And it must be inexpensive enough that any company can afford to put it on the desk of every person who can benefit from it.

Consider ease of use. Until a few years ago, all the effort was spent on making CAD programs work in the first place, and ease of use was an afterthought. With Inventor, ease of use is a primary consideration. The program has an exceptionally well thought-out interface, offering such features as a high-inferencesketcher and gesture-based interactivity.

In the realm of power, Inventor is a mixed bag, if only because it is still in its first release. One of its strengths is that it was designed from the ground up to handle very large assemblies. In one example provided by Autodesk, Inventor was able to load an assembly with 3100 components (of which 320 were unique) in 39 seconds on a 500mhz computer. I noticed, however, that the assembly provided (a manufacturing cell) included mostly simple parts, with few curved surfaces. So I created an assembly of 300 unique parts, each of which included complicated NURBS surfaces. On my 333mhz computer, it loaded in 73 seconds. And I was able to effectively edit any of the parts in the context of the assembly without undue delay.

Another strong area for Inventor is assembly editability. Most CAD systems create an ordered dependency between mated parts in an assembly. That is, if you change Part A, Part B will reflect the change, but you can`t change Part B and have Part A follow suit. Inventor, however, incorporates a unique technology, called Adaptive Assembly Modeling, which allows just this type of flexible assembly editing. To utilize Adaptive Assembly Modeling, the user selects which part features may change when a mating part changes.

The areas of weakness in Inventor are mostly missing features. Among the notable ones are advanced surface design, advanced lofting, exploded drawing views, and IGES translation.

The discipline for which Inventor is best suited is clearly industrial machinery design. The combination of large-assembly capabilities with adaptive assembly design makes Inventor a dream for this--and it is, in my opinion, a better choice in this area than any of its competitors. (One of those competitors is Autodesk`s own Mechanical Desktop program, which, though lacking Inventor`s adaptive technology, does handle integrated surface modeling. According to Autodesk, however, Inventor and Desktop are aimed at separate markets--advanced 3D MCAD design, and integrated 2D and 3D design respectively.)

Among those areas for which Inventor is not yet suited are sheet metal design, injection mold design, and any consumer product design requiring cosmetic surfaces. Inventor is not inherently limited in these areas; it`s simply that the specific tools necessary to address these disciplines aren`t present in this release of the software.

Autodesk has put three years of work into Inventor so far, and that time has included a lot of planning and foundation work. If Autodesk has planned successfully, it will ultimately be able to compete in the top tier of the CAD market and win the business of some of the most demanding customers. If it stumbles at all, it will be relegated to the mid-range market--which, although substantial, is also populated with strong competitors. One thing is clear, however: Autodesk is serious about the mechanical CAD market.

Evan Yares is a consultant, speaker, and writer in the field of engineering software. He is also president of the CAD Society.

Price: $4995
Minimum system requirements:
Windows 98/NT
300MHz Pentium CPU
512MB of RAM
100MB hard-disk space fast SCSI disk subsystem
OpenGL graphics adapter
4MB of video RAM

San Rafael, CA