The key is to know which operations have to be done in which order with the minimum viable tool path. Year by year, STEP-NC is adding more to the process data needed to know how to mill, drill or lathe a part, how to lead in, the speed at which to run and so on. Before this, machines controls worked blindly, not knowing what was allowed. When you know the tolerances manufacturing needs to meet, you can machine parts to those tolerances. What’s more, the addition of AP242e2 tolerances allowed STEP to be useful in automated manufacturing. Last year, AP238 version 2 was added for precision assembly. In 2005, AP238 version 1 was added to the STEP standard to incorporate precision machining. Since then, STEP has replaced IGES and has been extended into a machine tool control language, known as STEP-NC (numerical control). First released in 1995, STEP is sometimes referred to as “AP203” (level 2 application protocol). consortium to oversee STEP’s development.ĭefined by the EXPRESS data modeling language, STEP was designed to be extensible so that it could accommodate new technology. In 1988, a group of aircraft manufacturers formed the PDES, Inc. In 1985, the committee contributed PDES to an ISO initiative that had also initiated a universal file format designed to handle “anything from a microchip to a battleship.” This became known as the “STandard for the Exchange of Product model data” or STEP. “PDES is envisioned to support all aspects of product description, from initial conception through product design, manufacture, support, and disposal,” said the US Department of Commerce, describing what PLM sounds like today. In response, the IGES steering committee started a new file format, PDES. The solution was a common format, “initial graphics exchange specification” – IGES, for short.Īs IGES adoption increased, though, it also became unwieldy as it adapted to support data from an increasing number of MCAD systems. By 1976, however, MCAD had become common enough that the US Air Force demanded reduced costs in using files on the design floor from contractors. MCAD was rare enough that it didn’t matter that systems were incompatible. (Photo credit: STEP Tools Inc.)In the early days of mechanical CAD, there was no need to exchange model files. A STEP-NC file instructing the roughing, finishing, drilling and gear milling of a crown wheel with 105 operations and 925 tool paths.

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