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Product data exchange and interfacing between different CAD/CAM systems are of great importance to the development of concurrent integrated design environments and computer integrated manufacturing systems. This paper presents a STEP-based method and system for concurrent integrated design and assembly planning. An integrated object model for mechanical systems and assemblies is first defined by a hierarchy of structure, geometry and feature. The structure is represented as a component-connector or joint multi-level graph with both hierarchical functional and assembly relations. These hierarchical relation models are then used for uniformly describing their causal relations both for assembly level and feature based single part level. The generic product assembly model is organized according to STEP, using mostly the entities of integrated resources and partly self-defined entities, which are necessary for design and assembly planning. Based on the generic product assembly model, STEP-based strategies and agent concepts are used for agent-based concurrent integration of design and assembly planning. A prototype system, consisting of a CAD system, a product modeling system, an assembly planning system, and an assembly evaluation system is developed, in which product data can be exchanged between these subsystems. Details about the implementation of the system are addressed. The integrated design and assembly planning system can support the introduction of a new product. The results of assembly planning are feedback to the stage of assembly design to improve on the design. A case study is carried out for assembly-oriented design of a gearbox, to illustrate the proposed approach and to validate the developed system. [Copyright &y& Elsevier]

Product data exchange and sharing is an important issue for miscellaneous information systems. STEP-based product data exchange and sharing provides a useful mechanism for implementing concurrent engineering and promoting the realization of CALS' en vironment. This paper implements a pilot system for STEP-based PDE (Product Data Exchange) system based on the requirement of product data exchange between and within enterprises. The system incorporates engineering information in the design and manufactur ing stages and guarantees the consistency of the product data exchange and sharing. Complete development processes of systems, in cluding AAM (Application Activity Model), ARM (Application Reference Model), and AIM (Application Interpretation Model), are illustrated herein. AAM utilizing BPR (Business Process Reengineering) approach is employed to develop ARM, which is then mapped to AIM mod els from part 41, part 42, part 44, AP 203, AP 214 in STEP The system's database is based on the integrated AIM models in STEP to as sure the capability for product data exchange and sharing. The kernel data structure is a combination of engineering information and product-oriented definitions. The data from miscellaneous information systems, such as CAD/CAM, MRP/MRPII, ERP, and PDM, in the de sign and manufacturing phase of a product's life cycle can be exchanged using this system. This paper also employs STEP to present an integrated product-oriented data structure to manage engineering information from different information systems. [ABSTRACT FROM PUBLISHER]

A fundamental issue in concurrent engineering is sharing data among a vanety of commercially available computer-aided de sign, analysis, and manufacturing software tools. Geometry flaws often occur in the exchange of design data between dissimilar CAD systems and have multiplied with the ever-increasing complexity of product geometry. in recent years the international standard ISO 10303, STEP (Standard for the Exchange of Product model data), has achieved a success rate of 95-98% in the exchange of design data. This paper demonstrates that a significant portion of these errors are the result of the different degrees of precision used by com mercial CAD systems and are often apparent as minute gaps ranging from 0.00001-0.1 mm. The consequences are micro geometry gaps that are not visible to the designer but influence the creation of the final geometry at the receiver's end. Research has found that these gaps can be directly linked to the incompatibility in the degrees of precision used by individual CAD systems to associate vertices and curves with related faces. [ABSTRACT FROM PUBLISHER]