Feature technology and its applications in computer integrated manufacturing

A Thesis submitted for the degree of Doctor of Philosophy of University of LutonComputer aided design and manufacturing (CAD/CAM) has been a focal research area for the manufacturing industry. Genuine CAD/CAM integration is necessary to make products of higher quality with lower cost and shorter lead times. Although CAD and CAM have been extensively used in industry, effective CAD/CAM integration has not been implemented. The major obstacles of CAD/CAM integration are the representation of design and process knowledge and the adaptive ability of computer aided process planning (CAPP). This research is aimed to develop a feature-based CAD/CAM integration methodology. Artificial intelligent techniques such as neural networks, heuristic algorithms, genetic algorithms and fuzzy logics are used to tackle problems. The activities considered include: 1) Component design based on a number of standard feature classes with validity check. A feature classification for machining application is defined adopting ISO 10303-STEP AP224 from a multi-viewpoint of design and manufacture. 2) Search of interacting features and identification of features relationships. A heuristic algorithm has been proposed in order to resolve interacting features. The algorithm analyses the interacting entity between each feature pair, making the process simpler and more efficient. 3) Recognition of new features formed by interacting features. A novel neural network-based technique for feature recognition has been designed, which solves the problems of ambiguity and overlaps. 4) Production of a feature based model for the component. 5) Generation of a suitable process plan covering selection of machining operations, grouping of machining operations and process sequencing. A hybrid feature-based CAPP has been developed using neural network, genetic algorithm and fuzzy evaluating techniques

Computer-Aided Manufacturing Planning (CAMP)of Mass Customization for Non-rotational Part Production

This research is aimed at studying the key technologies of Computer-Aided Manufacturing Planning (CAMP) of mass customization for non-rotational part production. The main goal of the CAMP is to rapidly generate manufacturing plans by using of the best-of-practice (BOP) provided by specific companies. A systematic information modeling hierarchy is proposed to facilitate changes in manufacturing plans according to changes in part design. The Object-oriented Systems Analysis (OSA) approach is used to represent information relationships and associativities in the CAMP. A feature-based part information model, a process model, a setup planning model, and manufacturing resource capability models are established. A three-level decision-making mechanism is proposed for the CAMP. At the feature- level, combined features are defined based on part families, and a process model is proposed to describe the information associativities between features and their manufacturing strategies, which include customized cutters and toolpaths. At the part level, graph-based setup planning is carried out by tolerance analysis and manufacturing resource capability analysis. At the machine level, multi-part fixtures are utilized to pursue high productivity. Cycle time is used to evaluate manufacturing plans. Computer software for the CAMP has been developed and integrated with CAD package Unigraphs. The BOP of part families is stored in XML format, which has good extendibility and can be read and edited by standard browsers

Process planning for small batch manufacturing of sheet metal parts

The paper describes process planning for order-based small batch sheet metal part manufacturing. In this domain, general purpose CNC machinery and standard tools are being used. An example of a process planning system is given and some areas of special interest are discussed in more detail. Process planning for sheet bending and tolerance reasoning are important and intricate tasks within process planning, whereas abstractions in design and nesting are important due to their relations with other manufacturing functions. In general, manufacturing functions tend to become increasingly intertwined and traditional boundaries become blurred. Sheet metal industries, customers and suppliers alike, can benefit from this

Reason Maintenance in Product Modelling via Open Source CAD System

The present and future challenges of a new product design, forecasting and risk management launch strategy for a new product modelling decision process. This paper intends to propose and to look towards the development of a low-cost integrated CAD-CAPP-CAD/CAM product modelling system for the design and manufacture of a proposed product. It is a mapping between several design phases like functional design, technical design and physical design. The modelling data generation process begins with the drafting of a product to be maintained using the drafting software package. From the CAD drawing, the data are transferred to be used as the product models and a CAPP software package will then prepare the operational parameters for the manufacturing of the product. These process data are relayed to a CAM software package, which will then generate the automating information-processing functions. The final stage of the function is to support design and manufacturing operations that may have reaped many benefits in terms of its initial equipment and software costs

Heuristic classification for automated CAPP

In order to create a process plan from a workpiece description, a human expert thinks in a special terminology with respect to the given workpiece. The steps of human thinking during the generation process of a process plan are following the principles of heuristic classification: First using feature recognition an abstraction process isrealized yielding a high level (qualitative) description of the current workpiece in terms of features. To these features certain (more or less) abstract (partial) process plans--the so-called skeletal plans--are associated. In the refinement step these skeletal plans are merged together to one complete process plan. In this paper we present a set of domain-oriented higher level representation formalisms for features and skeletal plans suitable for the modeling of this approach. When an expert\u27s (process planner\u27s) knowledge has been represented using these formalisms, the generation of a process plan can be achieved by heuristic classification. This is demonstrated in the CAPP-system PIM, which is currently implemented as a prototype