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Computer Aided Design and Manufacturing
This book addresses the need to provide up-to-date coverage of current CAD/CAM usage and implementation. It covers, in one source, the entire design-to-manufacture process, reflecting the industry trend to further integrate CAD and CAM into a single, unified process. It also updates the computer aided design theory and methods in modern manufacturing systems and examines the most advanced computer-aided tools used in digital manufacturing. Computer Aided Design and Manufacturing consists of three parts. The first part on Computer Aided Design (CAD) offers the chapters on Geometric Modelling; Knowledge Based Engineering; Platforming Technology; Reverse Engineering; and Motion Simulation. The second part on Computer Aided Manufacturing (CAM) covers Group Technology and Cellular Manufacturing; Computer Aided Fixture Design; Computer Aided Manufacturing; Simulation of Manufacturing Processes; and Computer Aided Design of Tools, Dies and Molds (TDM). The final part includes the chapters on Digital Manufacturing; Additive Manufacturing; and Design for Sustainability. The book is also featured for being uniquely structured to classify and align engineering disciplines and computer aided technologies from the perspective of the design needs in whole product life cycles, utilizing a comprehensive Solidworks package (add-ins, toolbox, and library) to showcase the most critical functionalities of modern computer aided tools, and presenting real-world design projects and case studies so that readers can gain CAD and CAM problem-solving skills upon the CAD/CAM theory. Computer Aided Design and Manufacturing is an ideal textbook for undergraduate and graduate students in mechanical engineering, manufacturing engineering, and industrial engineering. It can also be used as a technical reference for researchers and engineers in mechanical and manufacturing engineering or computer-aided technologies.
eBook
Digital design : a critical introduction
\"Digital Design : A Critical Introduction provides a much-needed new perspective on designing with digital media. Linking ideas from media theory, generative design and creativity with examples from nature, art, architecture, industrial design, websites, animation and games, it addresses some fundamental questions about creative design with digital media. Featuring original material based on the authors' own research, the book argues that the recognition and understanding of the interplay of the two apparently opposing concepts of rules and contingency supports original thinking, creativity and innovation. Going beyond existing texts on the subject, Digital Design is an accessible primer whose innovative approach transcends the analysis of individual subfields - such as animation, games and website design - yet offers practical help within all of them\"-- Provided by publisher.
Book
STEP AP 242 Managed Model-based 3D Engineering: An Application Towards the Automation of Fixture Planning
Fixture design and planning is one of the most important manufacturing activities, playing a pivotal role in deciding the lead time for product development. Fixture design, which affects the part-quality in terms of geometric accuracy and surface finish, can be enhanced by using the product manufacturing information (PMI) stored in the neutral standard for the exchange of product model data (STEP) file, thereby integrating design and manufacturing. The present paper proposes a unique fixture design approach, to extract the geometry information from STEP application protocol (AP) 242 files of computer aided design (CAD) models, for providing automatic suggestions of locator positions and clamping surfaces. Automatic feature extraction software “FiXplan”, developed using the programming language C#, is used to extract the part feature, dimension and geometry information. The information from the STEP AP242 file is deduced using geometric reasoning techniques, which in turn is utilized for fixture planning. The developed software is observed to be adept in identifying the primary, secondary, and tertiary locating faces and locator position configurations of prismatic components. Structural analysis of the prismatic part under different locator positions was performed using commercial finite element method software, ABAQUS, and the optimized locator position was identified on the basis of minimum deformation of the workpiece. The area-ratio (base locator enclosed area (%)/work piece base area (%)) for the ideal locator configuration was observed as 33%. Experiments were conducted on a prismatic workpiece using a specially designed fixture, for different locator configurations. The surface roughness and waviness of the machined surfaces were analysed using an Alicona non-contact optical profilometer. The best surface characteristics were obtained for the surface machined under the ideal locator positions having an area-ratio of 33%, thus validating the predicted numerical results. The efficiency, capability and applicability of the developed software is demonstrated for the finishing operation of a sensor cover — a typical prismatic component having applications in the naval industry, under different locator configurations. The best results were obtained under the proposed ideal locator configuration of area-ratio 33%.
Journal Article
Advanced customization in architectural design and construction
This book presents the state of the art in advanced customization within the sector of architectural design and construction, explaining important new technologies that are boosting design, product and process innovation and identifying the challenges to be confronted as we move toward a mass customization construction industry. Advanced machinery and software integration are discussed, as well as an overview of the manufacturing techniques offered through digital methods that are acquiring particular significance within the field of digital architecture. CNC machining, Robotic Fabrication, and Additive Manufacturing processes are all clearly explained, highlighting their ability to produce personalized architectural forms and unique construction components. Cutting-edge case studies in digitally fabricated architectural realizations are described and, looking towards the future, a new model of 100% customized architecture for design and construction is presented. The book is an excellent guide to the profound revolution taking place within the fields of architectural design and construction, characterized by computational tools, advanced fabrication means and custom-made high-performance architecture.
Book
Development of STEP AP224 Extractor for Interfacing Feature Based CAPP to STEP-NC (AP238)
Manufacturing features represent area of interest on the machinable surface of a part, which can provide a unique set of removable volumes from part. Feature description in standard for exchange of product (STEP) AP224 is an efficient neutral format for the development of feature based process planning. Process planning information of features can be converted to numerical control (NC) code to have complete manufacturing information of part. STEP-NC code provides an efficient manufacturing information model compared to G-M codes. In this work, an interface is developed for extraction of feature information available in AP224 (AIM) format and the ruled-based approach is used to select different process planning parameters. A graphical user interface (GUI) is developed for the interface for displaying features information as represented in AP224 file. Furthermore, the interface generates STEP-NC code in AP238 format. The developed interface has three modules. 1) Module I: Reading interface for STEP AP224 file and development of GUI. 2) Module II: Selection of feature based process planning parameters. 3) Module III: Writing interface for STEP-NC (AP238). The developed interface has been implemented in Java through Java standard data access interface (JSDAI™). The generated STEP-NC AP238 code for the test part has been successfully simulated on STEP-NC Machine™, an AP238 simulator. This article also provides an in-depth view of application interpreted model (AIM) representation format of STEP for AP224 and AP238.
Journal Article
Evaluation of fit and efficiency of CAD/CAM fabricated all-ceramic restorations based on direct and indirect digitalization: a double-blinded, randomized clinical trial
Objectives
The aim of this clinical trial was to evaluate the marginal and internal fit of CAD/CAM fabricated zirconia crowns and three-unit fixed dental prostheses (FDPs) resulting from direct versus indirect digitalization. The efficiency of both methods was analyzed.
Materials and methods
In 25 patients, 17 single crowns and eight three-unit FDPs were fabricated with all-ceramic zirconia using CAD/CAM technology. Each patient underwent two different impression methods; a computer-aided impression with Lava C.O.S. (CAI) and a conventional polyether impression with Impregum pent soft (CI). The working time for each group was recorded. Before insertion, the marginal and internal fit was recorded using silicone replicas of the frameworks. Each sample was cut into four sections and evaluated at four sites (marginal gap, mid-axial wall, axio-occlusal transition, centro-occlusal site) under ×64 magnification. The Mann–Whitney
U
test was used to detect significant differences between the two groups in terms of marginal and internal fit (α = 0.05).
Results
The mean for the marginal gap was 61.08 μm (±24.77 μm) for CAI compared with 70.40 μm (±28.87 μm) for CI, which was a statistically significant difference. The other mean values for CAI and CI, respectively, were as follows in micrometers (± standard deviation): 88.27 (±41.49) and 92.13 (±49.87) at the mid-axial wall; 144.78 (±46.23) and 155.60 (±55.77) at the axio-occlusal transition; and 155.57 (49.85) and 171.51 (±60.98) at the centro-occlusal site. The CAI group showed significantly lower values of internal fit at the centro-occlusal site.
A quadrant scan with a computer-aided impression was 5 min 6 s more time efficient when compared with a conventional impression, and a full-arch scan was 1 min 34 s more efficient.
Conclusions
Although both direct and indirect digitalization facilitate the fabrication of single crowns and three-unit FDPs with clinically acceptable marginal fit, a significantly better marginal fit was noted with direct digitalization. Digital impressions are also less time-consuming for the dental practitioner and the patient.
Clinical relevance
The results show that a direct, intraoral, digitalized impression technique is more accurate and efficient when compared with conventional impressions in fabricating single crowns and three-unit FDPs.
Journal Article
Trueness of four different milling procedures used in dental CAD/CAM systems
Objectives
Milling is a crucial step in producing restorations using computer-aided design and computer-aided manufacturing (CAD/CAM) systems. In this study the trueness of currently available milling devices was evaluated.
Materials and methods
Thirty clinical cases (ten inlays, ten crowns, ten onlays) were milled from ceramic blocks using four different milling approaches: five axis with IMES CORiTEC 450i, four axis with CEREC MCXL, four axis with CEREC MCXL-EF and five axis with inLab MCX5. The milled restorations were scanned and the occlusal and inner surfaces compared to the originally calculated 3D surface using difference analysis software. The (90–10 %) / 2 percentile of the distances were calculated and analysed using one-way ANOVA with the post hoc Scheffé test (
α
= 0.05). Chipping of marginal areas were visually examined and analysed using one-way ANOVA with a post hoc Tamhane test (
α
= 0.05).
Results
At inner surfaces, the milling trueness of IMES (33.9 ± 16.3 μm), X5 (32.3 ± 9.7 μm) and MCXL-EF (34.4 ± 7.5 μm) was significantly better (
p
< 0.001) than that of MCXL (62.1 ± 17.1 μm). At occlusal surfaces, MCXL-EF (25.7 ± 9.3 μm) showed significant higher accuracy (
p
< 0.001) than MCXL (48.7 ± 23.3 μm) and X5 (40.9 ± 20.4 μm). IMES produced the most chipping (
p
< 0.001).
Conclusions
Five-axis milling devices yield high trueness. MCXL-EF is competitive and may allow chairside fabrication with good milling results.
Clinical relevance
Accurate milling is required for well-fitting restorations and thereby requires fewer manual finishing steps, yields smaller marginal gaps, resistance to secondary caries and longevity of restorations.
Journal Article
Machining robot with vibrational motion and 3D printer-like data interface
In this paper, a vibration motion control is proposed and implemented on a foamed polystyrene machining robot to suppress the generation of undesirable cusp marks, and the basic performance of the controller is verified through machining experiments of foamed polystyrene. Then, a 3 dimensional (3D) printer-like data interface is proposed for the machining robot. The 3D data interface enables to control the machining robot directly using stereolithography (STL) data without conducting any computer-aided manufacturing (CAM) process. This is done by developing a robotic preprocessor that helps to remove the need for the conventional CAM process by directly converting the STL data into cutter location source data called cutter location (CL) or cutter location source (CLS) data. The STL is a file format proposed by 3D systems, and recently is supported by many computer aided design (CAD)/CAM softwares. The STL is widely used for rapid prototyping with a 3D printer which is a typical additive manufacturing system. The STL deals with a triangular representation of a curved surface geometry. The developed 3D printer-like data interface allows to directly control the machining robot through a zigzag path, rectangular spiral path and circular spiral path generated according to the information included in STL data. The effectiveness and usefulness of the developed system are demonstrated through actual machining experiments.
Journal Article
On BIM Interoperability via the IFC Standard: An Assessment from the Structural Engineering and Design Viewpoint
Building information modelling (BIM) plays a prominent role in a good deal of architecture, engineering and construction (AEC) works, envisaging a full transition to digitalization for the construction industry. This is also due to a number of national and international regulations regarding the design, erection, and management of civil engineering constructions. For this reason, full interoperability of software environments such as computer-aided design (CAD) and computer-aided engineering (CAE) is a necessary requirement, particularly when the exchange of information comes from different disciplines. Users, throughout the years, have faced CAD–CAE interoperability issues despite following the IFC neutral open file format. This inability to share data (CAD to CAD, CAD to CAE) often generates model-interpretation problems as well as a lack of parametric information and a disconnection of elements. This paper addresses issues and mapping mechanisms in the exchange of data for the purpose of defining a baseline for the current status of bidirectional data exchange between AEC CAD/CAE software via the IFC format. A benchmark study, covering three years of software releases is illustrated; the assessment of the software performance was made with reference to criteria associated with the software’s level of suitability for use of the structural models. Four classes of performance, depending on the accuracy of the data transfer and on the associated corrective actions to be taken, were adopted. This confirmed that at the moment, the implementation of the IFC standard by software manufacturers is geared towards an expert class of users. Further efforts are needed in order to ensure its application is adopted by a wider class, thus extending and regulating its use by national, regional, and local authorities.
Journal Article