Journal of Manufacturing Systems Vol. 18/No. 2 1999 Efficient Sculptured Pocket Machining Using Feature Extraction and Conversion Jaekoo Joo, Dept. of Industrial and Systems Engineering, Inje University, Kimhae, South Korea Hyunbo Cho, Dept. of Industrial Engineering, Pohang University of Science and Technology (POSTECH), Pohang, South Korea Abstract A methodology is presented for finding a feature that can be used from design to manufacturing for sculptured pock- ets. A feature is the core concept necessary to realize a fully integrated CAD/CAM system; the information contents embedded in the feature can be easily conveyed from one application to another. However, the feature generated in one application may not be directly suitable for another without being modified with more information. This paper presents a methodology for decomposing a bulky feature of a sculptured pocket into compact features to be efficiently machined. In particular, the paper focuses on two tasks: (1) to horizontally segment a bulky feature into intermediate features and to generate their temporal precedence graph, and (2) to further decompose each intermediate feature vertically into smaller manufacturing features and to apply the variable feed rate to each small feature. The proposed method will provide better efficiency in machining time and cost than the classical method, which uses a long string of NC code. Keywords: CAD/CAM, Sculptured Pocket, Feature Extraction and Conversion, Feature-Based Process Planning Introduction The process planning system that links CAD and CAM generates a large amount of processing infor- mation related to different aspects of controlling a shop floor) A process plan is the "information set" that contains the instructions necessary to convert raw materials into finished products. Recent research has focused on how to smoothly integrate design, process planning, and manufacturing. A promising approach to the integration is feature- based process planning, which considers the machined part to be a collection of independent machinable features and fills up machining informa- tion on how to machine the features. The advantages of the approach are summarized as follows: First, it is easy and efficient to prepare a process plan that consists of a set of features and their removal sequence, because a feature contains machining information in a convenient way. Second, a feature can play a communication role in exchanging required data between applications. Recently, the feature-based approach has driven the research for the generative planning technique that can "auto- matically" determine the processing instructions for these independent features. As a direct result of intensive research, various new computer-based process planning tools have emerged recently that enable the process engineer to generate manufacturing instructions automatically for a large number of manufacturing features. Since the use of a feature is application-specific, however, a feature in a particular application can be interpret- ed differently in other applications. Each application has its own view of the feature. A feature of one view should convert into a feature of another view so the information contents used and/or generated in one application can be conveyed to another applica- tion, where they could be modified or appended with more information. For example, features used in the design stage should be converted into features for a process planner's view. Each manufacturing feature contains processes, primary machine resources, auxiliary resources, cutting parameters, and machine-level instructions needed to remove the complete shape of the feature identified in the process planning activities3 Each feature may have alternative resources, parameters, and instructions. This paper presents the life cycle of a feature used from design to manufacturing for sculptured pock- ets. In particular, the paper addresses the methodol- ogy necessary to decompose a bulky feature into compact features to be efficiently machined. The efficiency in machining the bulky feature is largely dependent on the cutter specification and cutting parameters. Consequently, the factors affecting machining efficiency should be considered in extracting manufacturing features. The detailed objectives of the paper are the two tasks: First, a bulky removal feature of the sculptured pocket is segmented into several thin layers called intermedi- 100