Investments in Computer Integrated Manufacturing Systems are driven by the desire for high‐quality components, small batch sixes, agility, and short lead times. In the early stages of part specification, the creation of an integrated CAD/CAM environment is the key to rapid off‐line simulation and verification of new part designs. Design, process planning, and manufacturing integration occurs at several levels depending upon the objective of the exercise and the degree of “flexibility” (that is to say the degree to which the design or process are fixed). The level of integration attainable between design, manufacturing, and finishing is dependent upon several factors (Stein and Dornfeld 1996):
- Nature of the design, manufacturing, or finishing task
- Environment in which the task is performed
- Tools available to assist the designer with the task
Four distinct levels of integration between the tasks of design, manufacturing, and finishing have been identified in present day and future production environment (Stein and Dornfeld 1997). Levels of integration can be described in terms of ability at each level to predict, influence, and optimize part production objectives at various stages of the total part production process. The objectives encompass a variety of process metrics which influence the goals of maintaining the tolerance of shape, tolerance of form, desired surface characteristics, and subsurface damage/residual stress. These four levels of integration from a process planning point of view are illustrated in Table 8.2, using feature quality as a process metric.
Table 8.2 Four levels of integration in the design to fabrication cycle.
Source: From Stein and Dornfeld (1997).
| Integration level | Process planning software expert and agent tasks | Degree of freedom for adjustment |
| Level I | Feature prediction, control, and optimization in an iterative design and process planning environment | Design: High Manufacturing: High Finishing: High |
| Level II | Feature prediction, control, and optimization through the selection of a manufacturing plan in an “over‐the‐wall” design‐to‐manufacturing environment | Design: Low Manufacturing: High Finishing: High > Low |
| Level III | Feature prediction and control through limited adjustments to a preestablished manufacturing process | Design: Low Manufacturing: Limited Finishing: High |
| Level IV | Feature prediction for finishing process planning, finishing tool trajectories, and sensor‐feedback strategies | Design: Low Manufacturing: Low Finishing: High |
At Level I, the highest level of integration, the designer is contemplating the design of the component. At this level, any information that correlates the design, the process plan, and manufacturing can be utilized to improve the overall “manufacturability” of the component. At a slightly lower level of integration, Level II, the design may be fixed, but it is still possible to develop a process plan and a manufacturing configuration to insure that the part specifications are met. At a still lower level, Level III, the design and process plan, as well as the machinery for manufacture, may be fixed. Even at this level, however, it is still possible and useful to consider optimization and fine‐tuning of the manufacturing process to accommodate unexpected problems through changes in total geometry or level of integration, and it may be of interest only to assist in insuring that subsequent manufacturing processes, such as finishing, for example, are efficiently and accurately carried out. As the level of integration between design, manufacturing, and finishing increases from Level IV to Level I, the ability of the software tools (and the designer) to influence and optimize the process metric of feature size, shape, or quality increases. The result of allowing the designer to work within the higher level of integration is to increase the sensitivity of design decisions for one process metric, such as burr formation, and to enable the designer to optimize and balance opposing process metric through analysis, simulation, and decision evaluation.
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