The various approaches proposed to provide communication between CAD systems and process planning systems share the major problem that, due to geometric interactions among features, there may be several equally valid sets of manufacturable features describing the same part, and different sets of features may differ in their manufacturability. Thus, to produce a good process plan-or, in some cases, any plan at ll-it may be necessary to interpret the part as a different set of features than the one initially obtained from the CAD model. This is addressed using an algebra of features. Given a set of features describing a machinable part, other equally valid interpretations of the part can be produced by performing operations in the algebra. This will enable automated process planning systems to examine these interpretations in order to see which one is most appropriate for use in manufacturing. The feature algebra has been implemented for a restricted domain and integrated with the Protosolid solid modeling system and the EFHA process planning system. >

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An algebraic approach to feature interactions

Rule-based automatic part feature extraction and recognition from CAD data

Prismatic parts usually comprise basic features, such as slots, steps, holes, bosses, which may intersect with one another. In general, automatic recognition of intersecting features is difficult and may present bottlenecks when automating the design procedures which make use of features for downstream operations. This paper presents a novel approach to recognising intersecting features and auxiliary features due to tool movements and cutter radii. Since no cutting edges can be perfectly sharp, corner fillets on machined features are invariably created by end mills and other cutters. Fillets, on the other hand, could very well be features which have been designed to increase strength and reduce stress concentration of certain features. A feature recognition system is proposed to recognise features having fillets which may be either design or manufacturing features. This information will be useful to the product designer as it would be possible to distinguish between the intended and unintended features of a part. The developed system has been implemented on an HP-ME30 Solid Modeler.

Automatic recognition of design and machining features from prismatic parts

Reverse Analysis Method of Unknown Protocol Syntax in Mobile Multimedia Communications

Feature modelling is a dynamic engineering domain. Many investigations have been introduced in this field in order to satisfy the automatic connection between design and manufacturing. The most ambiguous problem is feature definition; every one tries to suit particular or individual requirements. In this paper, a state of the art of feature is proposed, a feature taxonomy related to an autocad package is described and future work is mentioned.

Feature in CIM: what are problems?

An intelligent feature extraction methodology has been developed for use with a flexible manufacturing protocol. A wireframe input scheme based on the standard Initial Graphics Exchange Specifications format is used. The methodology has nine tasks. The first task involves the processing of a wireframe CAD file in the IGES format. The last task generates a feature file represented in another standard format. The intermediate tasks are concerned with locating the planes, the contours, the cylindrical surfaces and the boundary faces present within the part drawing. This methodology has been implemented on a Sun microcomputer within the Franz Lizp environment. The feature extractor runs in both automated and interactive modes. It accepts CAD files generated by any commercial CAD tool with an IGES interface. It has been tested with two such tools.

B. Kumar

Papers

Feature extraction and validation within a flexible manufacturing protocol