An integrated intelligent machining system for axisymmetric parts using PC-based CAD and CAM software packages

Machining process planning involves the formation of a set of directions describing the machining operations required to transform raw stock into a finished part. Conventional process planning, performed manually, relies on the knowledge and competence of an experienced process planner and tends to be time consuming and error prone. In the past two decades, much effort has been spent on improving process planning by utilizing the power of a computer to emulate the capabilities of an experienced planner. During the same period, computer-aided design (CAD) and computer-aided manufacturing (CAM) software has been developed to enhance design productivity and to assist the NC code generation facets of the machining process. The entire planning process may be automated be integrating CAD and CAM using computer-aided process planing (CAPP). The research described in this paper outlines the design and development of an intelligent CAPP system integrating two commercial CAD and CAM software packages, Autocad and Mastercam.     

STEP-NC based high-level machining simulations integrated with CAD/CAPP/CAM

With the development of manufacturing,numerical control(NC) machining simulation has become a modern tool to obtain safe and reliable machining operations.Although some research and commercial software about NC machining simulations is available,most of them is oriented for G&M code.It is a low-level data model for computer numerical control(CNC),which has inherent drawbacks such as incomplete data and lack of accuracy.These limitations hinder the development of a real simulation system.Whereas,standard for the exchange of product data-compliant numerical control(STEP-NC) is a new and high-level data model for CNC.It provides rich information for CNC machine tools,which creates the condition for an informative and real simulation.Therefore,this paper proposes STEP-NC based high-level NC machining simulations solution integrated with computer-aided design/computeraided process planning/computer-aided manufacturing(CAD/CAPP/CAM).It turned out that the research provides a better informed simulation environment and promotes the development of modern manufacturing.     

An integrated fixture planning and analysis system for machining processes

Fixture planning is an important part of computer-aided process planning (CAPP), which is the link between design and manufacturing in a CIM environment. This paper presents a rational approach to computer-assisted fixture planning (CAFP), emphasizing integration of fixture planning with process planning, an issue that has not been adequately addressed until very recently. A systematic approach to fixture selection is outlined for planning of modular fixtures. A prototype CAPP-CAFP system has been developed at UCLA and linked to a commercial CAD system, namely, CADAM. Part design information can be extracted from the CAD model and multiple-view engineering drawings of a part stored in the CADAM system. Modular fixture elements can be selected automatically by the CAPP-CAFP system and the generated fixture layout can be displayed on the screen. Included also in the system is a fixture analysis module for verification and rationalization of a fixturing scheme. The force analysis module has a built-in local optimization routine that can determine the clamping forces of more reasonable magnitudes. The friction forces between the fixture and the workpiece can also be considered for simple cases.     

Design of the database for CAD based on group technology

An important part of integrated CAD/CAPP/CAM is represented by the database in which all the information and data relevant for the design, planning and manufacturing of a component are available to the designer. The database must thus include relevant data about the geometrical primitives, materials, surfaces, tolerances, etc.This paper reports on the design of a database to be used in CAD/CAPP/CAM with particular reference to GT principles. The data required in the CAD process are strongly structured, so that their computer representation actually yields a structural model of the component. The elements which form the component model are parameterized shape primitives generating the matrix of the primitives for forming rotational and non-rotational components. The organization of their data and the communication between the designer and the database are discussed in detail. In this context a solution is proposed which enables the designer not only to draft a component by means of a computer, but, at the same time, to classify the component into a part family using a pattern recognition method for computer-aided GT classification.     

Design of a STEP compliant system for turning operations

The changing economic climate has made global manufacturing a growing necessity over the last decade, forcing companies from East and West to collaborate beyond geographic boundaries in the design, manufacture and assembly of products. The ISO 10303 and ISO 14649 Standards (STEP and STEP-NC) have been developed to introduce interoperability into manufacturing enterprises so as to meet the challenges of responding to production on demand. This paper describes and illustrates a STEP compliant CAD/CAPP/CAM System for the manufacture of rotational parts on CNC turning centers. The information models to support the proposed system together with the data models defined in the ISO 14649 standard used to create the NC programs are also described. A structured view of a STEP compliant CAD/CAPP/CAM system framework supporting the next generation of intelligent CNC controllers for turn/mill component manufacture is provided. Finally a proposed computational environment for a STEP-NC compliant system for turning operations (SCSTO) is described. SCSTO is the experimental aspect of the research and is supported by information models that and have been constructed using a structured methodology and object-oriented methods. SCSTO was developed to generate a Part 21 file based on machining features to support the interactive generation of process plans utilizing feature extraction. A case study component has been developed to prove the concept of using the milling and turning parts of ISO 14649 to provide a turn-mill CAD/CAPP/CAM environment.     

Computer-aided process planning—State of the art and future development

Computer-aided process planning (CAPP) is regarded as the critical link between design and manufacturing. Particularly in the integration of computer-aided manufacturing, process planning plays an outstanding role in the integrated flow of information.This paper gives a broad view of today's situation in computer-aided process planning in a real industrial environment. Characteristics for the classification of CAPP systems are derived and the main trends in the future development of CAPP software are pointed out. Feature-based modelling of manufacturing processes as the basis for integration-oriented software development is briefly described.     

Application of genetic algorithm to computer-aided process planning in preliminary and detailed planning

Computer-aided process planning (CAPP) is an important interface between computer-aided design (CAD) and computer-aided manufacturing (CAM) in the computer integrated manufacturing (CIM) environment. A good process plan of a part is built up based on two elements: (1) optimized sequence of the operations of the part; and (2) optimized selection of the machine, cutting tool and tool access direction (TAD) for each operation. On the other hand, two levels of planning in the process planning is suggested: (1) preliminary and (2) secondary and detailed planning. In this paper for the preliminary stage, the feasible sequences of operations are generated based on the analysis of constraints and using a genetic algorithm (GA). Then in the detailed planning stage, using a genetic algorithm again which prunes the initial feasible sequences, the optimized operations sequence and the optimized selection of the machine, cutting tool, and TAD for each operation are obtained. By applying the proposed GA in two levels of planning, the CAPP system can generate optimal or near-optimal process plans based on a selected criterion. A number of case studies are carried out to demonstrate the feasibility and robustness of the proposed algorithm. This algorithm performs well on all the test problems, exceeding or matching the solution quality of the results reported in the literature for most problems. The main contribution of this work is to emerge the preliminary and detailed planning, implementation of compulsive and additive constraints, optimization sequence of the operations of the part, and optimization selection of machine, cutting tool and TAD for each operation using the proposed GA, simultaneously.     

Hybrid feature recognition method for setup planning from STEP AP-203

For seamless automation, computer-aided design and manufacturing activities have to be linked by computer-aided process planning (CAPP). An important subtask in CAPP is setup planning, in which a setup plan must be generated ideally from a given 3-D model of the component. In this paper, a hybrid approach that effectively uses volume subtraction and face adjacency graph is proposed to recognize manufacturing features from 3-D model data in STEP AP-203 format. The proposed feature recognition is generic in nature and is capable of recognizing intersecting features also with relative ease. The manufacturing features are clustered based on preferential base for machining and a setup sequence is obtained by alternative rating and ranking. Finally, locating and clamping for each setup are determined considering intermediate shapes of the workpiece. This setup planning method reduces the number of alternatives for evaluation and thereby the computational effort.     

An integrated web-based CAD/CAPP/CAM system for the remote design and manufacture of feature-based cylindrical parts

This work describes the implementation of an integrated web-based CAD/CAPP/CAM system for the remote design and manufacture of feature-based cylindrical parts. This system, called WebMachining (), was developed in an e-manufacturing context, and the use of features allows the integration among the activities of collaborative design (WebCADbyFeatures), generative process planning (WebCAPP) and manufacturing (WebTurning). Through the WebCADby Features agent-based collaborative design module, cylindrical parts are modeled based on the synthesis of design features, in a Concurrent Engineering context. The WebCAPP generative CAPP module maps design features into machining features (including turning, milling, and drilling), and the mapping considers the setup, geometry, and operation. It uses a data structure similar to STEP-NC, and the generated process plans are nonlinear (i.e. they have alternatives). The WebTurning module performs the remote manufacture of the part, and it is based on a client–server architecture, where: (a) the servers are represented by the programs located at a workstation (Linux platform), which are connected to the machine tool through an Ethernet network interface; (b) the client is represented by a Java Applet. Some examples are provided in this paper, illustrating the remote design, process planning and manufacture of parts in a CNC turning center.     

A survey of feature modeling methods: Historical evolution and new development

Initially developed for geometric representation, feature modeling has been applied in product design and manufacturing with great success. With the growth of computer-aided engineering (CAE), computer-aided process planning (CAPP), computer-aided manufacturing (CAM), and other applications for product engineering, the definitions of features have been mostly application-driven. This survey briefly reviews feature modeling historical evolution first. Subsequently, various approaches to resolving the interoperability issues during product lifecycle management are reviewed. In view of the recent progress of emerging technologies, such as Internet of Things (IoT), big data, social manufacturing, and additive manufacturing (AM), the focus of this survey is on the state of the art application of features in the emerging research fields. The interactions among these trending techniques constitute the socio-cyber-physical system (SCPS)-based manufacturing which demands for feature interoperability across heterogeneous domains. Future efforts required to extend feature capability in SCPS-based manufacturing system modeling are discussed at the end of this survey.     

A feasible approach to the integration of CAD and CAPP

Although current CAD systems are declared to be feature-based, in fact, the so-called feature is just a modeling macro or menu name such as Protrusion, Revolution, Cutout, Block, etc., instead of a design feature or manufacturing feature in accordance with engineering practice. Consequently, product model data insufficiency and incompatibility between varieties of application systems are still the major barriers to system integration, especially the integration of design and process planning. This paper proposes a practical solution for a bi-directional integration of CAD and CAPP on the platform of commercial CAD systems. The key techniques such as feature recognition and conversion, feature parameter and constraint extraction, feature tree reconstruction, technical information processing, process planning, automatic process drawing marking and 3D material stock CAD model generating are discussed. And the extracted features and their related technical information and knowledge are encapsulated together with the geometry-oriented CAD model to form an integrated product information model to facilitate effective integration with the downstream activities. The integrated CAD/CAPP system is implemented on a commercial CAD package, UGS/SolidEdge. A case study and industry implementation illustrate the feasibility of the approach proposed.     

A PDES/STEP-based model and system for concurrent integrated design and assembly planning

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.     

PWA_Planner - A rule based system for printed wiring assemblies process planning

Using rule based approach, printed wiring assemblies (PWA) process planning can be automated. In this paper a prototype computer-aided process planning (CAPP) system for PWA, PWA_Planner, is presented. The system takes a PWA design as input and generates process plan and part programs for the production on automatic component mounting machines. The modelling of the problem and the final results are discussed in the paper.     

An architecture for the vertical integration of tooling considerations from design to process planning

To meet the competitive demands of modern manufacturing, it is necessary to reduce design times and enrich decision making by integrating process planning into the design activity using Concurrent Engineering principles. Although this is traditionally done through the interaction between designers and process planners, it is perhaps more desirable for a CAD system to have the functionality necessary to automatically advise the designer of the shop floor implications of design decisions. Cutting tool selection is an essential thread linking feature-based design of machined parts to process planning. Thus, the implementation of tooling considerations into design is an important requirement for an integrated CAD/CAPP system. This paper defines an architecture to enable the vertical integration of tooling considerations from early design to process planning and scheduling. The architecture is based on a five-level tool selection procedure which is mapped to a time-phased aggregate, management and detailed process planning framework. This paper draws on literature and the results of an industrial survey to identify the tooling methods suitable for integration within a CAD system and categorises them into the five levels of tool selection. The functions are then placed on a time-dependent framework that covers the progression of a product from design to process planning. The new functionality is being implemented as an object-oriented application called VITool, which is being developed so that it can be fully integrated within an existing CAD system.     

Cable harness design, assembly and installation planning using immersive virtual reality

Earlier research work using immersive virtual reality (VR) in the domain of cable harness design has shown conclusively that this technology had provided substantial productivity gains over traditional computer-aided design (CAD) systems. The follow-on work in this paper was aimed at understanding the degree to which various aspects of the immersive VR system were contributing to these benefits and how engineering design and planning processes could be analysed in detail as they are being carried out; the nature of this technology being such that the user’s activities can be non-intrusively monitored and logged without interrupting a creative design process or a manufacturing planning task. This current research involved the creation of a more robust CAD-equivalent VR system for cable harness routing design, harness assembly and installation planning which could be functionally evaluated using a set of creative design-task experiments to provide detail about the system and users’ performance. A design task categorisation scheme was developed which allowed both a general and detailed breakdown of the design engineer’s cable harness design process and associated activities. This showed that substantial amounts of time were spend by the designer in navigation (41%), sequence breaks (28%) and carrying out design-related activities (27%). The subsequent statistical analysis of the data also allowed cause and effect relationships between categories to be examined and showed statistically significant results in harness design, harness design modification and menu/model interaction. This insight demonstrated that poorly designed interfaces can have adverse affects on the productivity of the designer and that 3D direct manipulation interfaces have advantages. Indeed, the categorisation scheme provided a valuable tool for understanding design behaviour and could be used for comparing different design platforms as well as examining other aspects of the design function, such as the acquisition of design decision intent. The system also demonstrated the successful automatic generation of cable harness assembly and cable harness installation plans from non-intrusive user-system interaction logging, which further demonstrates the potential for concurrent design and manufacturing planning to be carried out.     

CATC — A Computer Aided Tolerance Control system

Computer utilization in manufacturing systems is increasing at a rapid rate. Developments thus far have been disjointed. Much work needs to be done in the area of integrating computer aided design and computer aided manufacturing (CAD/CAM). Tolerance control is an important component in the integration of CAD and CAM. Selection of design tolerances affects the build-ability of a product. The selection of manufacturing processes and sequence of processes affects process tolerance stacking. Unexamined process tolerance stacking leads to scrap and rework. A computer aided tolerance control (CATC) system is presented in this paper. This system is based on the tolerance chart technique. The CATC system is interactive and uses computer graphics for information display. The system can be used for computer aided process planning (CAPP) and for CAD/CAM integration.     

IKOOPPS: an intelligent knowledge-based object-oriented process planning system for the manufacture of progressive dies

Abstract: This article describes an intelligent knowledge-based object-oriented process planning (IKOOPP) system for the manufacture of progressive die plates. A die assembly is designed using a variety of standardised components based on a computer-aided design (CAD) system. A feature recognition module extracts all the pertinent geometrical properties and functional attributes of each machining feature from the CAD representation models. These properties and attributes are converted into an object-oriented representation. Knowledge of the functions of the machining feature allows process planning information to be automatically deduced. Specialised tool engineering knowledge are formulated as production rules or procedures to establish the required set of cutting tools, together with the machining allowances and sequence of operations.     

A knowledge intensive multi-agent framework for cooperative/collaborative design modeling and decision support of assemblies

Multi-agent modeling has emerged as a promising discipline for dealing with decision making process in distributed information system applications. One of such applications is the modeling of distributed design or manufacturing processes which can link up various designs or manufacturing processes to form a virtual consortium on a global basis. This paper proposes a novel knowledge intensive multi-agent cooperative/collaborative framework for concurrent intelligent design and assembly planning, which integrates product design, design for assembly, assembly planning, assembly system design, and assembly simulation subjected to econo-technical evaluations. An AI protocol based method is proposed to facilitate the integration of intelligent agents for assembly design, planning, evaluation and simulation process. A unified class of knowledge intensive Petri nets is defined using the O-O knowledge-based Petri net approach and used as an AI protocol for handling both the integration and the negotiation problems among multi-agents. The detailed cooperative/collaborative mechanism and algorithms are given based on the knowledge objects cooperation formalisms. As such, the assembly-oriented design system can easily be implemented under the multi-agent-based knowledge-intensive Petri net framework with concurrent integration of multiple cooperative knowledge sources and software. Thus, product design and assembly planning can be carried out simultaneously and intelligently in an entirely computer-aided concurrent design and assembly planning system.     

Automatic generation of variants depending on changes of product properties in a flexible manufacturing environment

Competition forces manufacturing systems to be flexible and to increase product variety and process complexity. These tasks depend on the flexible design of a bill of materials (BOM), one of the most important inputs in manufacturing planning and control systems. Product variety forces systems to generate BOMs with regard to product properties through a BOM pattern. A variant bill of materials provides a structure to manage product variability. In this study, an algorithm is designed to build a BOM pattern using computer-aided design and computer-aided manufacturing (CAD/CAM) data, and another algorithm is designed to generate variants with regard to product specifications. Genetic algorithm is used to generate new products to provide high product variability for testing algorithms. After the test, both algorithms are applied to a real industry problem. The BOM pattern is built automatically using CAD/CAM data, and variants are generated with regard to the pattern, and the results are discussed.     

Design of object-oriented database for the definition of machining operation sequences of 3D workpieces

This paper describes the activities of Object-Oriented (OO) analysis that were implemented in order to obtain a high part representation level and to give sets of structured and hierarchical data to the Computer Aided Process Planning (CAPP) system. The OO modeling activities were carried out by using the Object-Oriented System Analysis (OOSA) method which allows careful specification of all the information contained inside the system. All the models used by this method have been described in detail to show how the OO database is defined and how it can be used by a generative CAPP system. The feature model proposed is defined by taking all the part information that can be recognized and extracted from the Computer Aided Design (CAD) model into account. The result is the design of an OO database which allows the CAPP system to use manufacturing features to define machining operation sequences of 3D workpieces. The approach proposed is generic enough to integrate any geometrical forms which can be recognized and identified from the CAD system. Hole geometry is taken as an example to show the link between the step of OO analysis and the step of knowledge representation in the Expert System which has been used to generate machining cycles. The OO database presented makes up a real solution of CAD/CAPP/CAM integration by using feature modeling.