Elaboration and validation of AND/OR graph-based non-linear process plans for shop floor control

Feature-based process planning has been popular in academia and industry owing to its ability rigorously to integrate design and manufacturing. In spite of this benefit, feature-based process planning has been difficult to implement because it is not easy to extract even simple features from the design data automatically and efficiently. Furthermore, it is even more difficult to construct the temporal precedence relationships among the extracted features with regard to plan alternatives and sequence options. The objective here is to present elaboration and validation methodologies for AND/OR graph-based non-linear process plans that help users construct, validate or modify a controller-friendly process plan easily and efficiently. An elaborated process plan created by a CAPP or an experienced process planner should be validated with respect to various validation criteria, such as the shape of a finished part, feature interaction, feature interference, feature manufacturability and flexibility for shop floor control. For each validation criterion, the invalid indicator matrix proposed here can quantify the degree of invalidity of the process plan. The invalid indicator matrix will help the process planner fix and refine rapidly the elaborated process plan. The methodologies proposed will save cost and time in the production of a controller-friendly process plan. Initial results are promising.