Part design comes together on the Net

Part design comes together on the Net

by John Martin

McDonnell Douglas and Northrop Grumman linked their design and manufacturing teams in California and Texas through the Internet to develop a more affordable nacelle for the U.S. Air Force's C-17 airlifter

Among the pioneers in forming "virtual companies"--enterprises created by two or more businesses to bring a product to market that use the Internet as an information backbone so engineers and other personnel can function as if they were part of a single team--are McDonnell Douglas in St. Louis and Northrop Grumman in Dallas, which have joined forces to redesign the nacelle on the C-17 Globemaster III airlifter.

The C-17 Globemaster III’s four engines are encapsulated in the nacelles and attached to the wings by cantilevered pylons. The main focus of the redesign is affordability. The C-17 nacelle is unique, and the current version is relatively expensive.

Engineers use the same Unigraphics CAD/CAM system and database to perform design and manufacturing planning concurrently for the C-17 N/EAT nacelle, rendered here with Unigraphics

For the project, the two companies standardized on a common software platform, Unigraphics CAD/CAM software from EDS Unigraphics in Maryland Heights, Mo., along with that company's IMAN information-management software. The product design work is performed by McDonnell Douglas in Long Beach, Calif., and transmitted using Internet addresses to Northrop Grumman for tool design, numerical-control (NC) programming, and subsequent manufacture, fabrication, and assembly. McDonnell Douglas sends its progressive releases as full 3-D solid models to Dallas. The target is fully digital operation.

The team needs to maintain the connectivity between all the parts, so that changes are reflected throughout the entire assembly. IMAN software helps the virtual team keep track of all revisions made during the concurrent product-development process, with access made available to product design, tool design, release control, illustrations, manufacturing engineering, planning, tool handling, and NC programming. The two companies send Cercast in Canada the 3-D Unigraphics model, and Cercast develops the tools to build the casting in Unigraphics directly from that digital information.

The companies report they are getting shorter lead times, and they expect that the parts produced will go together better the first time, with less interference and reduced engineering changes, rework, and repair after the fact.

The above was adapted from an article by John Martin, a consultant in Endicott, N.Y., who focuses on computer-aided design, manufacturing, engineering, and product development. The full text may be found in the June 1997 issue of Mechanical Engineering magazine. © 1997 ASME International.© To obtain a copy of this issue, click here.