GA Based Feature Recognition of Step File for CAD/CAM Integration

Feature-based method has been successfully applied in several fields of manufacturing. However, most of the applications use the solid modeling method that cannot meet the requirements of a product design that needs a free-form surface or a complicated surface. This research utilizes the Genetic Algorithm (GA) technique for feature recognition of STEP file. A GA model is proposed for optimizing the coordinates which is used for feature recognition. It is proposed as an input for automatic feature recognition in Computer Aided Design and Manufacturing (CAD/CAM) application. These methods accomplish their task based on recognition of features as GA made up. This technique used standard for exchange of product information (STEP) formats for geometrical data extraction representation to matching the coordinate from STEP file to decide the correct or optimize solution. Genetic operator such as selection, crossover and mutation are performed repeatedly to acquire the optimal sequences of coordinates. Even though the result of this processes are optimal, some coordinates are not placed in the correct position

CAD/CAM integration based on machining features for prismatic parts

The development of CAD and CAM technology has significantly increased efficiency in each individual area. The independent development, however, greatly restrained the improvement of overall efficiency from design to manufacturing. The simple integration between CAD and CAM systems has been achieved. Current integrated CAD/CAM systems can share the same geometry model of a product in a neutral or proprietary format. However, the process plan information of the product from CAPP systems cannot serve as a starting point for CAM systems to generate tool paths and NC programs. The user still needs to manually create the machining operations and define geometry, cutting tool, and various parameters for each operation. Features play an important role in the recent research on CAD/CAM integration. This thesis investigated the integration of CAD/CAM systems based on machining features. The focus of the research is to connect CAPP systems and CAM systems by machining features, to reduce the unnecessary user interface and to automate the process of tool path preparation. Machining features are utilized to define machining geometries and eliminate the necessity of user interventions in UG. A prototype is developed to demonstrate the CAD/CAM integration based on machining features for prismatic parts. The prototype integration layer is implemented in conjunction with an existing CAPP system, FBMach, and a commercial CAD/CAM system, Unigraphics. Not only geometry information of the product but also the process plan information and machining feature information are directly available to the CAM system and tool paths can be automatically generated from solid models and process plans

Design for manufacture using machining features on CNC machining centers

Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM) systems have become more and more needed and useful in the machining processes environment. In order to achieve competitive advantage, companies adopted new manufacturing methods. As a consequence, and in machining processes context, the interaction of CAD and CAM has growth over the years in order to increase the production efficiency, as well as to reduce costs and time. The development of this work started with an extensive literature review. In that review, the author found that only a few articles approached the interaction or integration of CAD and CAM systems. Moreover, the authors that studied this interaction focused on systems for turning parts. Thus, there is a gap in the literature related to the integration and automation of these systems when applied to milling parts. Therefore, the purpose of this dissertation is to enable the interaction of these systems in order to provide a completely automated process since the design stage until the machining stage. Finally, the process’ implementation showed that the developed algorithm was able to satisfy the initial requirements of this work, i.e., when given a set of initial parameters, the program drew the required geometry, and then generated the required G-code, such that this code can be sent to the CAM software to machine the workpiece, thereby obtaining the final product.Os sistemas Computer-Aided Design (CAD) and Computer-Aided Manufacturing(CAM) estão, cada vez mais, a ser mais necessários e úteis no contexto da maquinagem. De modo a conseguir vantagem competitiva, as empresas têm adotado novos métodos de produção. Consequentemente, no contexto da indústria da maquinagem, a interação entre CAD e CAM tem crescido nos últimos anos, de modo a permitir uma maior eficácia na produção, assim como também redução de tempo e custo. O desenvolvimento deste trabalho começou com uma extensa revisão da literatura. Nesta revisão, o autor apercebeu-se que apenas alguns artigos se debruçaram sobre a interação ou integração dos sistemas CAD e CAM. Para além disso, os autores desses artigos focaram-se em sistemas para torneamento. Assim, constata-se que existe um espaço livre na literatura no que diz respeito à integração destes sistemas quando aplicados à fresagem. Por isso, o objetivo desta dissertação é permitir a interação dos dois sistemas referidos, de forma a promover um processo completamente automático desde o design até à maquinagem. Por fim, a implementação do processo mostrou que o algoritmo desenvolvido alcançou os objetivos iniciais do trabalho, ou seja, baseando-se apenas nos parâmetros fornecidos, o programa desenhou as geometrias necessárias, sendo depois capaz de gerar o código G respetivo, para que este possa ser transferido para o centro de maquinagem, de modo a que o material possa ser maquinado, dando origem ao produto final

Integration of sketch-based ideation and 3D modeling with CAD systems

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis is concerned with the study of how sketch-based systems can be improved to enhance idea generation process in conceptual design stage. It is also concerned with achieving a kind of integration between sketch-based systems and CAD systems to complete the digitization of the design process as sketching phase is still not integrated with other phases due to the different nature of it and the incomplete digitization of sketching phase itself. Previous studies identified three main related issues: sketching process, sketch-based modeling, and the integration between the digitized design phases. Here, the thesis is motivated from the desire to improve sketch-based modeling to support idea generation process but unlike previous studies that only focused on the technical or drawing part of sketching, this thesis attempts to concentrate more on the mental part of the sketching process which play a key role in developing ideas in design. Another motivation of this thesis is to produce a kind of integration between sketch-based systems and CAD systems to enable 3D models produced by sketching to be edited in detailed design stage. As such, there are two main contributions have been addressed in this thesis. The first contribution is the presenting of a new approach in designing sketch-based systems that enable more support for idea generation by separating thinking and developing ideas from the 3D modeling process. This kind of separation allows designers to think freely and concentrate more on their ideas rather than 3D modeling. the second contribution is achieving a kind of integration between gesture-based systems and CAD systems by using an IGES file in exchanging data between systems and a new method to organize data within the file in an order that make it more understood by feature recognition embedded in commercial CAD systems.This study is funded by the Ministry of Higher Education of Egypt

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

Manufacturing Feature Recognition With 2D Convolutional Neural Networks

Feature recognition is a critical sub-discipline of CAD/CAM that focuses on the design and implementation of algorithms for automated identification of manufacturing features. The development of feature recognition methods has been active for more than two decades for academic research. However, in this domain, there are still many drawbacks that hinder its practical applications, such as lack of robustness, inability to learn, limited domain of features, and computational complexity. The most critical one is the difficulty of recognizing interacting features, which arises from the fact that feature interactions change the boundaries that are indispensable for characterizing a feature. This research presents a feature recognition method based on 2D convolutional neural networks (CNNs). First, a novel feature representation scheme based on heat kernel signature is developed. Heat Kernel Signature (HKS) is a concise and efficient pointwise shape descriptor. It can present both the topology and geometry characteristics of a 3D model. Besides informative and unambiguity, it also has advantages like robustness of topology and geometry variations, translation, rotation and scale invariance. To be inputted into CNNs, CAD models are discretized by tessellation. Then, its heat persistence map is transformed into 2D histograms by the percentage similarity clustering and node embedding techniques. A large dataset of CAD models is built by randomly sampling for training the CNN models and validating the idea. The dataset includes ten different types of isolated v features and fifteen pairs of interacting features. The results of recognizing isolated features have shown that our method has better performance than any existing ANN based approaches. Our feature recognition framework offers the advantages of learning and generalization. It is independent of feature selection and could be extended to various features without any need to redesign the algorithm. The results of recognizing interacting features indicate that the HKS feature representation scheme is effective in handling the boundary loss caused by feature interactions. The state-of-the-art performance of interacting features recognition has been improved

Intelligent techniques for automatic feature recognition in CAD models

The solutions suggested in this research are implemented in a prototype AFR system and its performance verified on commonly used benchmarking parts that are composed of machining features.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Intelligent techniques for automatic feature recognition in CAD models

The solutions suggested in this research are implemented in a prototype AFR system and its performance verified on commonly used benchmarking parts that are composed of machining feature

Integrated process planning and scheduling for common prismatic parts in a 5-axis CNC environment

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Automated feature recognition system for supporting engineering activities downstream of conceptual design.

Transfer of information between CAD models and downstream manufacturing process planning software typically involves redundant user interaction. Many existing tools are process-centric and unsuited for selection of a "best process" in the context of existing concurrent engineering design tools. A computer based Feature-Recognition (FR) process is developed to extract critical manufacturing features from engineering product CAD models. FR technology is used for automating the extraction of data from CAD product models and uses wire-frame geometry extracted from an IGES neutral file format. Existing hint-based feature recognition techniques have been extended to encompass a broader range of manufacturing domains than typical in the literature, by utilizing a combination of algorithms, each successful at a limited range of features. Use of wire-frame models simplifies product geometry and has the potential to support rapid manufacturing shape evaluation at the conceptual design stage. Native CAD files are converted to IGES neutral files to provide geometry data marshalling to remove variations in user modelling practice, and to provide a consistent starting point for FR operations. Wire-frame models are investigated to reduce computer resources compared to surface and solid models, and provide a means to recover intellectual property in terms of manufacturing design intent from legacy and contemporary product models. Geometric ambiguity in regard to what is ?solid? and what is not has plagued wire-frame FR development in the past. A new application of crossing number theory (CNT) has been developed to solve the wire-frame ambiguity problem for a range of test parts. The CNT approach works satisfactorily for products where all faces of the product can be recovered and is tested using a variety of mechanical engineering parts. Platform independent tools like Extensible Mark-up Language are used to capture data from the FR application and provide a means to separate FR and decision support applications. Separate applications are composed of reusable software modules that may be combined as required. Combining rule-based and case-based reasoning provides decision support to the manufacturing application as a means of rejecting unsuitable processes on functional and economic grounds while retaining verifiable decision pathways to satisfy industry regulators