Most DoD programs acquiring electronic systems have depended on contractor definition of the Computer-Aided Design (CAD) systems that facilitate product design and development. Independent definition of basic requirements has allowed use or nonuse of CAD as a tool to achieve these requirements. In many cases, CAD systems are considered as a "tool " for simplifying the design task without recognizing the full benefits provided by CAD to introduce discipline throughout the plant operation. Technical discipline throughout the design process ensures success in complex development projects.
Since the use of adequate CAD technology is a significant factor in reducing the risk in development projects, particularly as those projects make the transition from development into production, the use of CAD technology should be encouraged. Therefore, it is recommended that CAD capability be recognized as a factor in source selection. Companies with a definite corporate policy with regard to CAD/CAM, and those companies that have proven capability in effective use of this technology should be ranked higher. As a general rule, the use of CAD systems should not be considered project-unique requirements and contractually funded. Although some product-peculiar CAD activities may occasionally be appropriate, CAD activities should be oriented to support all of the factory's product lines.
What constitutes a good CAD system? CAD systems vary widely and range from stand-alone "personal" terminals to complex, interactive systems that require the use of complex and expensive host computer systems for data manipulation. An optimum CAD capability would provide each design engineer with a simple stand-alone terminal and provide an interactive terminal with a more comprehensive graphics team analysis capability for every for to six design engineers
The software used with these CAD terminals has paramount importance of the effectiveness and efficiency of the design control achieved through the use of CAD. Integrate CAD/CAM software architecture for multiple access and control, coupled with a common database, greatly improves system effectiveness and facilitates the design-to-production transition. The software that should be evident in a good CAD system include special analyses such as stress, vibration, thermal, noise, and weight. In addition, the CAD system should permit simulation modeling using finite element analysis and solids modeling. Such a system can cut the design/drafting process time by factors of four or five. The scope and thoroughness of these analyses are limited only by the programs available in the computer system.
The software package should be used in conjunction with
a CAD/CAM database that includes (as a minimum):
a. design specifications including mission profile, performance limits and
requirements, and reliability requirements
b. design standards and rules that support company policies
c. verified libraries of preferred electronic parts with both performance
and physical characteristics, including tolerances
d. preferred mechanical parts
e. previously manufactured and qualified assemblies
f. materials, processes, and finishes
g. manufacturing processes, standards, and rules
h. design data including analytical results
i. manufacturing data, including:
- design release status
- test status
- test and failure analysis
- manufacturing yield and trend analysis
j. tool design
of design release and configuration
Corporate policy that defines CAD technology as an integrated part of an
overall factory modernization strategy is a low risk, effective approach to
the development and use of CAD technology. Approaches that use
computer-assisted technology (CAD, CAE, and CAM) in a piecemeal or "band aid"
approach without careful consideration to the total plant-wide picture can be
guaranteed a most difficult and costly system phase in from a lack of hardware
and software compatibility. In addition, continuous and aggressive corporate
involvement is required to enhance CAD capabilities. These enhancements are
necessary to provide new analysis tools for manufacturing processes and
updates of parts data information as high technology parts become
Once the CAD system is "on-line," it will be design engineer's effective
use of his new design tool that will determine the benefit of the CAD system.
The design engineer must, therefore, be made aware of the full capability of
his CAD system. A formal training program for all users of CAD should be
implemented. Such a training program should be integrated with other plant
operations that are introducing computer-assist capability. This training
program will ensure acceptance of the "new way of doing business," and ensure
full use of the CAD system's features that may not be apparent from system