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Since the 1980s, manufacturers have sought to close the gap between CAD/CAM and the processes used to create a part, to make seamless the transfer of data from the designer's desk to the CNC.
Conventional NC (RS 274D) codes and the post-processor they require are geared around the machine—not the part. Many would like to reverse this, to use a language that's part-, not machine-specific. This would not only make machine language more portable, it would solve incompatibility problems. According to the National Institute of Standards and Technology, data incompatibility creates a $90-billion loss annually for U.S. manufacturing.
Enter STEP, or the Standard for the Exchange of Product Model Data. The movement calls for a standard engineering language that can ease the flow of information from the designer's desk all the way through metal cutting and inspection, eliminating machine-specific G- and M-codes in the process. All operations, say STEP supporters, should instead be driven from the same root file.
"Basically, engineers want to define once and use everywhere," says Martin Hardwick, president of STEP Tools Inc. (www.steptools.com), the Troy, N.Y., company leading the U.S. push toward the new machining language.
STEP's Story
For the past three decades, engineers have tried to standardize computerized engineering data in all its forms. In the early 1980s, they had to deal with multiple CAD systems with various file formats. So experts from Boeing, GE and elsewhere helped develop IGES, or the Initial Graphics Exchange Specification. Around that time, French engineers developed their own standard file format—SET—while Germany used its VDAFS. All focused on geometric data exchange.
But to take the exchange to the next level, companies found they needed "one integrated format that can grow to all engineering functions over time," says Hardwick.
Enter the International Standards Organization and the move toward STEP. Efforts were begun in all strains of engineering computer data, in CAD/CAM as well as computer-aided engineering and others.
Within the CAD/CAM arena, ISO gave its final blessings in 1995 to Application Protocol 203 (AP 203), an internationally standardized data file that captures all the geometric data from CAD needed for manufacturing.
Developing the format was a bit easier than what came next: Standardizing data from CAM. Thousands of attributes attach to each geometry feature for different manufacturing parameters of parts, from machine speed to toolpaths to tolerances to the units used for those tolerances. "There's a seemingly endless stream of qualifications that engineers need, not all of the time, but some of the time," Hardwick says. And "some of the time" means those functions must be written into the software.
The final draft of this format—AP 238—was finally approved by ISO last June, and a final software platform is projected to be released this summer.
