19 research outputs found
Feature technology - an overview
Manufacture is an objective that has become more urgent within the wider context of a total
Computer Integrated Manufacturing environment. In seeking this integration it is recognised
that the diversity of activities and consequent needs for data can best be served by a single
representation for design, design analysis and manufacturing planning, and that a strong
candidate for this descriptive role is a Feature Representation. This paper briefly overviews
the primary methods of the use of features through Feature Recognition and Design by
Features, particularly in the process planning application area
Feature technology : an overview
The proper integration of the activities of computer-aided design (CAD) and computer-aided manufacture (CAM)is an objective that has become more urgent within the wider context of a total computer integrated manufacturing (CIM) environment. In seeking this integration it is recognized that the diversity of activities and consequent needs for data can best be served by a single representation for design, design analysis and manufacturing planning, and that a strong candidate for this descriptive role is a feature representation. This paper briefly overviews the primary methods of the use of features through feature recognition and design by features, particularly in the process planning application area
Process capability modelling: a review report of feature representation methodologies
Approximately 150 technical papers on the features methodology have been carefully studied and some selected
papers have been commented upon. The abstracts of the comments are documented and attached to this report. The
methodologies reviewed are mainly divided into two approaches, ie. feature recognition and design by features.
Papers which deal with some specific topics such as feature taxonomies, dimensions and tolerances, feature
concepts, etc. are also included in the document
Implementation aspects of a feature-based design system for manufacturing planning
A prototype feature-based design system for process planning is described. The system contains a design by features user interface which is developed within a Boundary Representation modeller; a feature modeller for manipulation of feature data; and an information mapper (feature processor) to transform design information into a form suitable for the planning system. In principle, the design system can be tailored for applications other than process planning by the use of alternative information mapping mechanisms. Emphasis is given to the software implementation aspects of the feature-based design system, such as the design and implementation of the user interface, the arrangement of the additional feature modelling functions together with standard solid modelling functions, the communication mechanism between different data models, and the tools used for the implementation
Feature validation in a feature-based design system
The Loughborough University of Technology Feature-Based Design System (LUTFBDS)
allows detail design to be carried out in a computer aided design (CAD)
environment by the addition of form features to stock material or part-machined
components. An iconic user interface assists in the description parts in terms of a set
of primitive features such as holes, pockets and slots or higher level compound
features such as patterns of holes and counterbored holes. This feature representation
is generated in parallel with the geometric data structure of the underlying boundary
representation solid modeller. The feature representation is useful for a range of
downstream manufacturing activities, but our research focusses on the integration of
CAD with process planning. LUT-FBDS functions allows the designer or manufacturing
engineer to progressively construct the final geometry of a part, and facilities are
provided for the designer to modify parameters which relate to feature dimensions,
location, orientation and relationships with other features. These changes may result in
changes to the feature representation and hence there is a need for feature validation
to ensure the integrity of the model
Geometric elements for tolerance definition in feature-based product models
Product modelling is an essential part of all computerised design and
manufacturing activities. A precise mathematical model of the geometry of
products is important, but must be supplemented with technological information
such as the material, mechanical properties, functional specifications and
tolerances. Modern CAD systems can model and manipulate components with
complex geometry. However, technological information is represented as text
symbols on the computer screen or drawing, and subsequent application
programs are frequently unable to use this information effectively. This paper
discusses this problem, and establishes the geometric elements required for the
representation or dimensions and tolerances in a feature-based product
modelling environment
Knowledge representation and re-use in FMEA
The research described in this paper addresses the ability rapidly and easily to create product variants through the capture and re-use of design and manufacturing knowledge. New methodologies are envisaged that enable companies to anticipate problems before they occur, thus transferring them from ‘reactive’ to ‘predictive’. The implementation of predictive design represents the crucial move from standard parts to standard knowledge constructs. Standard parts can be used in any application that requires a defined function where the shape and properties do not need to be altered. However, standard knowledge constructs can provide parts that can be used wherever the function is required. Examples of the technique are presented from recently completed research concerning FMEA applied to electronic products
A design by features approach to the building of feature data models for process planning
As research and development in Computer Aided Design and
Manufacture (CAD/CAM) progresses, the integration of activities such as
design, analysis, process planning, assembly planning, production planning
becomes ever more complex and important. It has been recognized that a
feature based representation of parts is a key to solving this problem.
Unfortunately, neither has a feature representation scheme (or standard) yet
been generally accepted, nor has a CAD system successfully represented
feature information.
Ongoing research into process capability modelling is aimed at solving
the above problems in the process planning domain. In this paper, a design
by features system, which consists of a design by features user interface and
an integrated Boundary Representation solid modeller, is introduced. A
feature representation scheme that has been implemented in the system is
also presented. Although the design by features approach still has limitations,
it overcomes some severe problems with the alternative feature recognition
approach, such as the complexity of the recognition process, the limited
number of features that can be identified from the geometric representations
of pans and the absence of the designer's intent
The implementation of a feature-based component representation for CAD/CAM integration
Recent research and development has the objective of increasing productivity and cost effectiveness by integrating many activities such as design, analysis, process planning, assembly planning and production planning which encompass the entire manufacturing planning and operational control aspects of a manufacturing enterprise. It has been recognized that a key to the integration lies in the determination of a representation scheme for products that can be interpreted for the various needs of these different applications. Geometric (solid) modellers were regarded by many researchers as the appropriate representation, but more recently a features approach has been proposed to enhance the capabilities of solid modellers.
This paper introduces ongoing research which is aimed at the development of a feature-based design system for process planning. The system is fully integrated with a conventional boundary representation (Brep) modeller which enhances its modelling capabilities in representing, editing and validating features of components. The main aspects of the feature-based design system are described in detail, such as the feature library, feature taxonomy, feature operations, feature relationships and tolerances. The generation of a detailed data model for transmission to manufacturing planning activities is also described and demonstrated by reference to an example component. A brief indication is given of our parallel research work in using such models as the basis of process planning and process capability modelling
An experimental comparison of a feature based design system and a conventional solid modeller
Computer-Aided Design (CAD) systems are currently widely used in design and
manufacturing industries. However, the integration of CAD systems with Computer-
Aided Manufacturing (CAM) systems such as process planning, graphical numerical
control (NC part programming), assembly and inspection planning requires a featurebased
representation of components which is not found in conventional geometry-based
CAD systems. To meet this requirement, feature-based CAD systems have been
developed in research centres worldwide using feature-oriented user interfaces and
feature-based representations of parts. The introduction of new technology (feature-based
design in this instance) always raises important questions. For example, are feature-based
systems easier to learn and more efficient than conventional geometric modellers?; and
does the method generate more complete and accurate models? This paper reports an
experiment which was carried out to compare a prototype feature-based design system
with a conventional solid modeller, where both systems use an iconic interface. Eight
engineering students were selected as subjects and each subject was required to generate
six features using both systems. The time taken to generate each feature was recorded and
the results were presented as a series of graphs and learning curves. The results of the
experiment show that both systems are similar in terms of learning their operation and that
the feature's approach has clear efficiency gains over the conventional geometric
approach. The conclusions drawn from this experiment may be useful for both end users
who are considering upgrading their existing systems and software vendors who are
designing next generation of products