A Double-Edged Sword
Having processing diversity can be a blessing and it can be a curse. The up side of offering numerous process choices is that a larger variety of work can be manufactured. On the down side, it's sometimes more difficult to get all of the efficiency from a given process that a specialized shop working exclusively with one screw machine type may be able to achieve.
Basic part checking and sophisticated measurement are responsibilities of the Enoch machinist. Gages are kept at the machine for checking parts. Measurement devices are available for use by the machinist in the quality control room. QC personnel consult with machinists to help them operate the gaging machines.
Before purchasing a CAM package, see how the software imports files from every customer you work with to determine for certain that there are no data-transferring issues.
A solution is actively being studied. The International Standards Organization (ISO) is working with American, European and Asian businesses and government agencies to implement a standard for transferring electronic data, called the International STandard for theExchange of Product Model Data (STEP). Essentially, STEP is a common structure, operating as a template, for sharing data among multiple users, across all functional areas.
"Communication among different departments and different software is a problem," says Mr. Keller. "Interaction is important for shortening the product life cycle. STEP will enable us to iterate designs based on manufacturing suggestions, then evaluate and analyze the results before manufacturing the pieces. It also offers a tremendous benefit for reusing and managing information from several engineering and manufacturing disciplines in an effective way."
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| At the NASA Ames Research Center, the design team shares CAD/CAM data with craftsmen who carry laptop computers with them on the shop floor. |
There are several sections within STEP, called Application Protocols (APs), which are built into a common data model. These APs include definitions not only of typical geometry and drafting elements, but also of data types and processes for specific industries such as automotive, aerospace, shipbuilding, electronics, plant construction and maintenance. The most common AP in current use is AP203, which is focused on geometric elements for mechanical CAD. AP203 is further subdivided into classes for defining wireframe geometry, surfaces and solid modeling. To facilitate the transfer of information, STEP is built on a data exchange language, called EXPRESS, which formally describes the structure and correct conditions of a file's engineering information.
"The specification for IGES is written so that, theoretically, several interpretations are available, producing the different CAD flavors," says Mr. Keller. "The committees involved in writing the STEP standard are working toward eliminating the differences in reading entities, as in the case of IGES." Mr. Keller hopes that pressure from government contracts and large commercial users will require vendors and suppliers to validate their STEP translators and eventually eliminate variances in the interpretations.
Until STEP issues are resolved and there is one definite standard for data transfer, individual shops must continue to work with several CAD formats, depending on their customers' software requirements. Save time, money and labor by researching your CAM software and translators before you make a purchase. Although there may be issues beyond the control of CAM translators, well-written and robust versions can read and correct for many CAD data anomalies.
