Until recently, it took an excruciatingly long time for the Navy to obtain certain parts for its equipment, especially where the parts were designed many years ago. An average lead time of 300 days created frequent delays in getting military equipment back in service. Then, the Navy streamlined the process with a new system, called Rapid Acquisition of Manufactured Parts (RAMP), which is described later.

Reasons for the former turtle-like pace can be summed up in three words: paper, complexity, and age. First, the information required to design and manufacture a part (or assembly) typically consists of drawings, specifications, and instructions to shop personnel, all on paper.

Where the assembly is a complex weapons system, the package of paper information grows to huge proportions. Typically, several subcontractors prepare this information, each interpreting differently the contractor’s drawing requirements. As a result, the package often contains inconsistencies, incomplete or inaccurate information, or extraneous information.

Old designs complicate the situation further. Where the parts were designed many years ago, the information degrades over time — drawings are lost, aperture cards (microfilm) deteriorate, and details become fuzzy as copies are copied. Moreover, the original materials and manufacturing processes may become obsolete.

Years later when replacement parts are needed, engineers must reassemble all of the data before the parts can be manufactured. This often requires reverse engineering, a process in which the engineer measures an original part to recreate some or all of the design information (see box). It may also be necessary to revise the design to accommodate new requirements. This takes time, which means higher cost and later delivery.

Further, as time passes, the original parts vendors may go out of business, while others either have no interest in manufacturing small quantities of parts or they charge a high price for doing so.

Obviously, a more efficient way of handling product data would avoid these problems and benefit both the Navy and its many suppliers, including, for example, manufacturers of drivetrain components and control electronics for mobile equipment.

RAMP to the rescue

To cut excessive lead time, the Naval Supply Systems Command initiated the RAMP program in 1986. Its primary objective: shorten the 300-day average lead time for delivery of small quantities of parts to a mere 30 days. Another objective was to obtain quality parts the first time they are made, and at reasonable cost. The Navy selected the South Carolina Research Authority (SCRA), North Charleston, S.C., as prime contractor for the program.

The SCRA formed a team to come up with a more efficient way to handle product data and support flexible computerintegrated manufacturing (FCIM). The SCRA FCIM Team — including Arthur D. Little, Battelle, Grumman Data Systems, and SEACOR (Systems Engineeering As sociates Co.) — developed a product data translation system (PDTrans), that rapidly converts paper data into a computerized digital format for use by designers and manufacturers.

Mechanical and electrical parts

PDTrans exists in two configurations: one for machined mechanical parts and one for printed wiring assemblies, as typified by Figures 1 and 2. Both of these versions create digital product data either for new designs — generated on a CAD system — or for existing designs — usually by scanning paper drawings and specifications or aperture cards. In a physical sense, the two configurations, Figure 3, are the same: a commercial CAD/CAM workstation with CAD/CAE and database management software, plus translation software developed by the SCRA FCIM Team. But the similarity ends there.

Mechanical. The first configuration, for mechanical parts, converts paper data into a digital format that is consistent with an evolving international standard for exchanging product data, called STEP (See box). Using an SCRA system that includes feature-based CAD software and an SCRA translator, a user can convert a moderately complex mechanical part from paper to STEP format in about an hour.

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