The characteristics of the CAT to CAD to rapid prototyping system

ThesisComputer Aided Design (CAD), Rapid Prototyping (RP) and Computer Aided Tomography (CAT) technologies were researched. The project entails a unique combination of the abovementioned technologies, which had to be mastered by the author, on local and international terms. Nine software packages were evaluated to determine the modus operandi, required input and final output results. Fifty Rapid Prototyping systems were investigated to determine the strong and weak areas of the various systems, which showed that prototype materials, machine cost and growing time play an essential role. Thirty Reverse Engineering systems were also researched. Six different RE methods were recorded with several commercial systems available. Nineteen case studies were completed by using several different Computer Aided Tomography (CAT) and Magnetic Resonance Imaging (MRI) centers. Each scanning centre has different apparatus and is discussed in detail in the various case studies. The focus of this project is the data transfer of two dimensional CAT scanning data to threedimensional prototypes by using Reverse Engineering (RE) and Rapid Prototyping (RP). It is therefore of cardinal importance that one is familiar and understands the various fields of interest namely Reverse Engineering, Computer Aided Tomography and Rapid Prototyping. Each of these fields will be discussed in detail, with the latest developments in these fields covered as well. Case studies and research performed in the medical field should gain the medical industry's confidence. Constant marketing and publications will ensure that the technology is applied and transferred to the industry. Commercialisation of the technology is of utmost importanc

Using feature-based product modelling to integrate design and rapid prototyping

Rapid prototyping (RP) provides a means of producing physical models directly from computer aided design (CAD) data. The aim of this research was to determine the most effective method of integrating RP into the design process. A review of the links between design and RP was undertaken. This revealed that RP is a technology which can benefit several key areas of engineering design. Many computer tools were identified which supported the designer's use of RP but most of these relied on using CAD geometry alone. Using this incomplete set of design information hindered the integration of RP into the design process. A hypothesis was formulated which stated that a feature-based product modelling methodology was needed to enable RP to become an integrated part of the design process. To demonstrate the validity of the methodology, it was embodied in a design support system (DSS) for rapid prototyping. The DSS requirements were determined through a survey of designers using RP, and a full specification for the system was defined. A demonstration version was implemented using a relational database coupled with a CAD system. The demonstration DSS enabled feature-based geometry and non-geometric information to be integrated within a single product model. An application program was developed which used the product model data to optimise the orientation of an RP model in order to meet the differing surface finish requirements for each feature in a component. This example use of the system illustrated the benefit of using a feature-based product model to optimise the designer's use of RP. Future work needed to improve the DSS to a state where it would be ready for development into a commercial package was identified. Finally, conclusions were drawn as to how all the objectives were met and summarising the original contribution to knowledge made by the research

Design And Modeling of Axial Micro Gas Turbine

Micro turbines are becoming widely used for combined power generation and heat applications. Their size varies from small scale units like models crafts to heavy supply like power supply to hundreds of households. Micro turbines have many advantages over piston generators such as low emissions less moving parts, accepts commercial fuels. Gas turbine cycle and operation of micro turbine was studied and reported. Brief description on CAD software and CATIA studied and reported. Different parts (Inlet. Storage, Nozzle, Rotor , coupling ,outlet ,clip ,housing) of turbine are designed with the help of CATIA (Computer Aided Three Dimensional Interactive Analysis) software. Then they were assembled to a single unit and coupled to a generator to produce power. The turbine is of Axial input and axial output type. Finally rapid prototyping machine features and parts were discussed and presented

Qualification of rapid prototyping tools: proposition of a procedure and a test part

Rapid prototyping machines are becoming faster at manufacturing machine tools. The processes of quality assurance impose the qualification of the production devices. A procedure and a test part are proposed for that purpose; intended for the family of processes of point-by-point layer manufacturing. Existing test parts only permit benchmarking and comparisons between machines: their capacity can be evaluated, but the test part analysis does not make it possible to establish the link between noted defects and their causes. The proposed process and test part permit the identification of the defects and whether their origins are machine or material linked. This paper describes the approach used to design the test part. Some preliminary measures were made on a test part, in order to discuss procedure and measurements

Using feature-based product modelling to integrate design and rapid prototyping

Rapid prototyping (RP) provides a means of producing physical models directly from computer aided design (CAD) data. The aim of this research was to determine the most effective method of integrating RP into the design process. A review of the links between design and RP was undertaken. This revealed that RP is a technology which can benefit several key areas of engineering design. Many computer tools were identified which supported the designer's use of RP but most of these relied on using CAD geometry alone. Using this incomplete set of design information hindered the integration of RP into the design process. A hypothesis was formulated which stated that a feature-based product modelling methodology was needed to enable RP to become an integrated part of the design process. To demonstrate the validity of the methodology, it was embodied in a design support system (DSS) for rapid prototyping. The DSS requirements were determined through a survey of designers using RP, and a full specification for the system was defined. A demonstration version was implemented using a relational database coupled with a CAD system. The demonstration DSS enabled feature-based geometry and non-geometric information to be integrated within a single product model. An application program was developed which used the product model data to optimise the orientation of an RP model in order to meet the differing surface finish requirements for each feature in a component. This example use of the system illustrated the benefit of using a feature-based product model to optimise the designer's use of RP. Future work needed to improve the DSS to a state where it would be ready for development into a commercial package was identified. Finally, conclusions were drawn as to how all the objectives were met and summarising the original contribution to knowledge made by the research

The feasibility of using virtual prototyping technologies for product evaluation

With the continuous development in computer and communications technology the use of computer aided design in design processes is becoming more commonplace. A wide range of virtual prototyping technologies are currently in development, some of which are commercially viable for use within a product design process. These virtual prototyping technologies range from graphics tablets to haptic devices. With the compression of design cycles the feasibility of using these technologies for product evaluation is becoming an ever more important consideration. This thesis begins by presenting the findings of a comprehensive literature review defining product design with a focus on product evaluation and a discussion of current virtual prototyping technologies. From the literature review it was clear that user involvement in the product evaluation process is critical. The literature review was followed by a series of interconnected studies starting with an investigation into design consultancies' access and use of prototyping technologies and their evaluation methods. Although design consultancies are already using photo-realistic renderings, animations and sometimes 3600 view CAD models for their virtual product evaluations, current virtual prototyping hardware and software is often unsatisfactory for their needs. Some emergent technologies such as haptic interfaces are currently not commonly used in industry. This study was followed by an investigation into users' psychological acceptance and physiological discomfort when using a variety of virtual prototyping tools for product evaluation compared with using physical prototypes, ranging from on-screen photo-realistic renderings to 3D 3600 view models developed using a range of design software. The third study then went on to explore the feasibility of using these virtual prototyping tools and the effect on product preference when compared to using physical prototypes. The forth study looked at the designer's requirements for current and future virtual prototyping tools, design tools and evaluation methods. In the final chapters of the thesis the relative strengths and weaknesses of these technologies were re-evaluated and a definitive set of user requirements based on the documentary evidence of the previous studies was produced. This was followed by the development of a speculative series of scenarios for the next generation of virtual prototyping technologies ranging from improvements to existing technologies through to blue sky concepts. These scenarios were then evaluated by designers and consumers to produce documentary evidence and recommendations for preferred and suitable combinations of virtual prototyping technologies. Such hardware and software will require a user interface that is intuitive, simple, easy to use and suitable for both the designers who create the virtual prototypes and the consumers who evaluate them

A comparison of processing techniques for producing prototype injection moulding inserts.

This project involves the investigation of processing techniques for producing low-cost moulding inserts used in the particulate injection moulding (PIM) process. Prototype moulds were made from both additive and subtractive processes as well as a combination of the two. The general motivation for this was to reduce the entry cost of users when considering PIM. PIM cavity inserts were first made by conventional machining from a polymer block using the pocket NC desktop mill. PIM cavity inserts were also made by fused filament deposition modelling using the Tiertime UP plus 3D printer. The injection moulding trials manifested in surface finish and part removal defects. The feedstock was a titanium metal blend which is brittle in comparison to commodity polymers. That in combination with the mesoscale features, small cross-sections and complex geometries were considered the main problems. For both processing methods, fixes were identified and made to test the theory. These consisted of a blended approach that saw a combination of both the additive and subtractive processes being used. The parts produced from the three processing methods are investigated and their respective merits and issues are discussed

Optimising additive manufacturing for fine art sculpture and digital restoration of archaeological artefacts

Additive manufacturing (AM) has shown itself to be beneficial in many application areas, including product design and manufacture, medical models and prosthetics, architectural modelling and artistic endeavours. For some of these applications, coupling AM with reverse engineering (RE) enables the utilisation of data from existing 3D shapes. This thesis describes the application of AM and RE within sculpture manufacture, in order to optimise the process chains for sculpture reproduction and relic conservation and restoration. This area poses particular problems since the original artefacts can often be fragile and inaccessible, and the finishing required on the AM replicas is both complex and varied. Several case studies within both literature and practical projects are presented, which cover essential knowledge of producing large scale sculptures from an original models as well as a wide range of artefact shapes and downstream finishing techniques. The combination of digital technologies and traditional art requires interdisciplinary knowledge across engineering and fine art. Also, definitions and requirements (e.g. ‘accuracy’), can be applied as both engineering and artistic terms when specifications and trade-offs are being considered. The thesis discusses the feasibility for using these technologies across domains, and explores the potential for developing new market opportunities for AM. It presents and analyses a number of case study projects undertaken by the author with a view to developing cost and time models for various processes used. These models have then been used to develop a series of "process maps", which enable users of AM in this area to decide upon the optimum process route to follow, under various circumstances. The maps were validated and user feedback obtained through the execution of two further sculpture manufacturing projects. The thesis finishes with conclusions about the feasibility of the approach, its constraints, the pros and cons of adopting AM in this area and recommendations for future research