The roots of DFM date as far back as World War II [5]. Scarcity of resources, and constant social and political pressure to build better weapons in the shortest possible turnaround time were the main motivating factors behind the tight integration of design and manufacturing activities. Many of the successful weapons of that period were designed by small, integrated, multi-disciplinary teams [5]. However, with the the post-World War II era of prosperity and the resultant rapid growth of industry size came the segregation of design and manufacturing departments, which resulted in a sequential product development environment with little attention to DFM. Increasing global competition and desire to reduce lead time led to the rediscovery of DFM in the late 1970s. Some of the earliest attempts involved building inter-departmental design teams that consisted of representatives from the design and manufacturing departments. In these design projects, manufacturing engineers participated in the design process from the beginning and made suggestions about possible ways of improving manufacturability [6,7]. Such inter-departmental design teams did not always work harmoniously and many management-related problems existed when building and coordinating such teams [8].
In an attempt to increase the awareness among designers of manufacturing considerations, leading professional societies have published a number of manufacturability guidelines for a variety of manufacturing processes [4,9,10,11,12]. Some companies produced and used their own guidebooks for designers---one of the pioneers was General Electric [13]. These guidelines mainly enumerate the design configurations that pose manufacturability problems and were intended as training tools in DFM. To practice DFM, the designer had to carefully study these guidelines and try to avoid those configurations that result in poor manufacturability.
The availability of low-cost computational power is providing designers with a variety of CAD tools to help increase productivity and reduce time-consuming build-test-redesign iterations. Examples include tools for finite element analysis, mechanism analysis, simulation, and rapid prototyping. The availability of such tools has become a driving force for research in concurrent engineering where various product life-cycle considerations are addressed at the design stage. As the advantages of concurrent engineering are being realized, more and more downstream activities associated with the various manufacturing aspects are being considered during the design phase, and DFM has become an important part of concurrent engineering [3,4].
One of the primary goals of concurrent engineering is to build an intelligent CAD system by embedding manufacturing related information into the CAD systems. In intelligent CAD systems, DFM is achieved by performing automated manufacturability analysis---a process which involves analyzing the design for potential manufacturability problems and assessing its manufacturing cost. It is expected that these systems will alleviate the need to memorize and study the manufacturability checklists, therefore allowing the designers to focus on creative aspects of the design process. Moreover, as the manufacturing resources or practices change in an organization, the knowledge bases of these intelligent CAD systems could be updated automatically with least interference with the design activities of the organization.
It has become evident that the task of manufacturability analysis requires extensive geometric reasoning. As the field of solid modeling has matured, functional and architectural improvements in modelers have facilitated increasingly sophisticated types of geometric reasoning. The closed architecture solid modeling systems of the late 1980's did not allow easy access and manipulation of geometric and topological entities, most of the computer-aided DFM tools developed in that period did not rely on extensive geometric reasoning. This, in turn, limited their capacity for handling complex design shapes. In recent years, the functional capabilities of commercial systems has been vastly improved. These new enhancements, coupled with the advent of open architecture solid modeling systems [14], facilitate implementation of the complex geometric reasoning techniques required for realistic manufacturability analysis.
Manufacturability analysis is becoming an important component of CAD/CAM systems. Inadvertent designer errors, such as missing a corner radius or excessively tight requirements for surface finish, that go undetected during the design stage may prove costly to handle in a fully automated CAD/CAM system (i.e. the system might select an expensive manufacturing operation to achieve that erroneous design attribute). It is anticipated that a systematic methodology for manufacturability analysis will help in building systems to identify these types of problems at the design stage, and provide the designer with the opportunity to correct them.