The trends of rapid manufacturing (RM) have influenced numerous developments of technologies mainly in additive processes. However, the material compatibility and accuracy problems of additive techniques have limited the ability to manufacture end-user products. More established manufacturing methods such as Computer Numerical Controlled (CNC) machining can be adapted for RM under some circumstances. The use of a 3-axis CNC milling machine with an indexing device increases tool accessibility and overcomes most of the process constraints. However, more work is required to enhance the application of CNC for RM, and this thesis focuses on the improvement of roughing and finishing operations and the integration of cutting tools in CNC machining to make it viable for RM applications. The purpose of this research is to further adapt CNC machining to rapid manufacturing, and it is believed that implementing the suggested approaches will speed up production, enhance part quality and make the process more suitable for RM. A feasible approach to improving roughing operations is investigated through the adoption of different cutting orientations. Simulation analyses are performed to manipulate the values of the orientations and to generate estimated cutting times. An orientations set with minimum machining time is selected to execute roughing processes. Further development is carried out to integrate different tool geometries; flat and ball nose end mill in the finishing processes. A surface classification method is formulated to assist the integration and to define the cutting regions. To realise a rapid machining system, the advancement of Computer Aided Manufacturing (CAM) is exploited. This allows CNC process planning to be handled through customised programming codes. The findings from simulation studies are supported by the machining experiment results. First, roughing through four independent orientations minimized the cutting time and prevents any susceptibility to tool failure. Secondly, the integration of end mill tools improves surface quality of the machined parts. Lastly, the process planning programs manage to control the simulation analyses and construct machining operations effectively.

Published Article / Long-term growth in the additive fabrication industry will come from designs that are difficult, time-consuming, costly, or impossible to produce using standard techniques. Growth will occur with advances in the current additive processes, coupled with breakthroughs in new materials, which are expected to emerge over the next five to 10 years. These advanced materials will better satisfy the design requirements of many new products. The paper considers currently available technologies and discusses recent advancements in direct metal freeform fabrication and its potential of revolutionising the medical industry.

Published Article / This article looks at the role that vacuum casting plays in the rapid prototyping and rapid manufacturing process. The accuracy to which components can be reproduced, by looking at the controllable factors in the casting process and the different types of materials that are available, were investigated and the process was also compared to other rapid prototyping and manufacturing processes in terms of cost effectiveness. Castings were made from a typical component under different operating conditions and the characteristics of the cast component, dimensions strength and surface hardness, were measured and plotted to determine the characteristics and accuracy of the process.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Published Article / RP and recently RM have been key factors in the development of the manufacturing industry in assisting in the development of new products. Fortunately, the application of these technologies has been realised in the medical industry. Surgeons all over the world use physical models created from CT or MRI data using some sort of additive manufacturing. The fabrication of these models has exploded into a popular research area combining engineering, material and medical expertise. Long-term growth in the additive fabrication industry will come from designs that are difficult, time-consuming, costly, or impossible to produce using standard techniques. Growth will occur with advances in current additive processes which are coupled with breakthroughs in new materials. The applications of RP and RM are as diverse as the medical issues that arise. RM of custom design medical prostheses proves to be economically viable solution, not only because it is faster to produce but it gives the designer freedom of creation too. The paper discusses some interesting medical case studies.

Published Article / e-Manufacturing means the fast, flexible and cost-effective production of parts directly from electronic data, which can include rapid prototyping, rapid tooling, (spare) parts on demand etc. Especially interesting is the direct manufacture of enduse parts. In this paper, recent case studies will be presented showing commercial e-Manufacturing projects including small production batches and mass customized series production from various industrial branches. The paper also discusses the relevance of several recent technological innovations in laser-sintering for e- Manufacturing, especially how increasing the productivity of machines and process chains has increased the range of applications which are cost-effective using lasersintering. <br>Case studies include: <ul> <li> small series production (up to a few thousand p.a.) of products</li> <li> production of customized (one-off) products</li> <li> mass production of customer-specific (mass customized) products</li> <li> optimized tooling concepts for production of up to millions of products</li> </ul>

Published Article / At Helsinki University of Technology rapid prototyping, rapid tooling and rapid manufacturing technologies and applications have been researched since late 1980s. The Integrated Design and Manufacturing research group has concentrated on new industrial Rapid Prototyping and Manufacturing (RP&M) applications within product development and manufacturing. This paper is based on research projects realized in 2001 - 2004 in cooperation with several industrial companies. New developments within industrial product development paradigms and processes will be discussed. The paper attempts to link current industrial management sciences research with latest developments within rapid manufacturing technologies. Product platforms, product customization and networked manufacturing have become common product development management paradigms in many industrial sectors. These paradigms have lead to an increasing number of product configurations and variations. Traditionally cost comparisons between RP&M processes and conventional manufacturing processes have been based on break even point calculations. The latest product development and manufacturing paradigms places agility in production and efficient prototyping technologies among others in an important role. Conventional cost per part comparison methods to value rapid manufacturing need to be re-engineered. In those comparisons the first break even point does not describe the overall rapid manufacturing economy. For example, effects of neccesity for product change, tool wear or tool defect have to be taken into consideration. In this paper the new cost modeling technology and some industrial case studies will be described.

La intenció d'aquest projecte de recerca és anar més enllà de l' aconseguit pels sistemes existents de selecció i comparació de processos de Prototipat Ràpid, mitjançant la introducció d'una nova metodologia que tingui com a únic fi la 'Fabricació Final' de components. El sistema desenvolupat incorpora algunes de les eines més recents del camp de Intel·ligència Artificial, de manera que sigui possible aconseguir una metodologia concurrent que inclogui: · Sistemes experts, que s'executen durant el procés de presa de decisions amb alternatives múltiples. Els sistemes experts utilitzen típicament estructures del tipus: IF-THEN-ELSE o CASE, de manera que les opcions puguin ser 'cribrades' especialment durant les primeres etapes de la selecció. · Lògica difusa per a la presa de decisions. Normalment en l'àmbit de la fabricació, alguns termes lingüístics o paràmetres de tipus qualitatiu són utilitzats per definir estats o propietats. Per exemple és comú trobar termes qualitatius com ara: 'bones propietats mecàniques "o" alta taxa d'absorbència', en lloc de xifres i números puntuals. Per tant és necessari comptar amb un mètode per traduir i gestionar aquesta informació. La lògica difusa ha estat adoptada com a mitjà per traduir termes d'ordre qualitatiu a informació quantitativa de manera que a partir d'aquestes dades es pugui construir un sistema de classificació i rànquing de processos.· Presa de decisions Multi-criteri, agrupació (sumatòria) i classificació. Durant la investigació es van provar diferents mètodes per a la classificació d'alternatives i selecció final a partir de vectors d'ordre quantitatiu amb pesos ponderats. Per a aquesta finalitat es va adoptar la metodologia proposada per Lan et al. (2005) el qual es descriu en el capítol 5 d'aquest treball. · Xarxes Neuronals Artificials. Aquestes han estat aplicades per a la modelització i simulació d'alguns processos de Fabricació Ràpida prèviament seleccionats. Per exemple, el procés de Sinteritzat Selectiu Làser es va aconseguir modelar utilitzant Xarxes Neuronals amb un algorisme de "backpropagation", prenent com a informació base, les dades proporcionades pel software propietari de l'equip. Aquesta xarxa neuronal simula una màquina de sinteritzat làser model DTM Vanguard, disponible a la FundacioCIM-UPC a Barcelona. D'altra banda el procés de Fusió selectiva per làser ha estat modelat també mitjançant Xarxes Neuronals a partir de l'equip Concep Laser M2, disponible al laboratori d'Enginyeria mecànica de la Universitat Catòlica de Lovaina, Bèlgica. Els models extrets d'aquestes simulacions mostren una estimació del temps total de fabricació menor al 10% la qual cosa representa una millora substancial respecte a mètodes d'estimació paramètrics. · Finalment s'ha utilitzat la tècnica de bases de dades relacionals per a la gestió i emmagatzematge d'informació sobre materials. Aquestes bases de dades han estat creades en Ms Access, que proporciona la facilitat d'accés, filtrat, graficació i presentació de la informació requerida. Aquesta informació pot ser extreta automàticament mitjançant trucades ODBC, executades des de l'entorn Matlab.Per a il·lustrar el funcionament de les eines descrites en una forma integrada, s'ha optat per desenvolupar una aplicació pilot en Matlab, utilitzant alguns "Tool boxes" especialitzats com: Lògica difusa, Xarxes neuronals, Estadística, Utilitats de graficació, Creació d'interfície d'usuari (GUI), Bases de dades. El resultat d'aquesta integració és una aplicació pilot anomenada RMADS (Rapid Manufacturing Advice System), el qual compta amb una interfície gràfica d'usuari que es divideix en tres mòduls: · Requeriments generals de disseny. Aquest mòdul analitza els paràmetres usualment definits en les especificacions inicials de Producte, per exemple: tipus de material, toleràncies, acabat superficial, complexitat geomètrica, etc. · Mòdul de costos. Aquest mòdul utilitza paràmetres d'entrada prèviament introduïts com: volum de peça, mida de lot i dimensions totals, per a realitzar càlculs mitjançant mètodes paramètrics i models basats en xarxes neuronals. El resultat és una estimació del cost per peça i també el cost estès per volums grans. · Selecció de materials. Aquest mòdul mostra la natura iterativa del procés de selecció de materials, a través de criteris de "filtratge" o selecció, de manera que a cada iteració el nombre d'opcions sigui limitat a un nombre raonable d'alternatives. / The intention of this research is to go beyond currently available systems for the assessment and selection of Rapid Prototyping processes, hence introducing a new methodology devoted to 'Manufacturing' applications. Specifically the system would include a number of state of the art artificial Intelligence techniques to comprise a fully concurrent methodology, namely:· Expert systems are included to aid in the decision making process with multiple alternatives. Expert systems typically use If-Then-Else or CASE structures so that the available options can be screened specially during the first selection stages.· Fuzzy logic for decision making. Usually in manufacturing, linguistic terms or qualitative parameters are used to define states of properties. For instance it is common to find terms such as 'Good mechanical properties' or 'High absortivity rates' therefore it is necessary to have a method to translate and manage such information. Fuzzy logic has been adopted as a means to translate qualitative terms to quantitative information.· Multi-criteria decision making, aggregation and ranking. Different methods for selecting and ranking alternatives were tested which allows the integration of quantitative vectors with weighting factors that reflect the user preferences. For this purpose the method proposed by Lan et al. (2005) has been adopted as discussed in Chapter 5.· Artificial Neural Networks (ANNs) are being applied for the modelling and simulation of a number of Rapid Manufacturing Methods. Selective Laser Sintering has been modelled using a back propagation algorithm ANN taking as a basis the information provided by the machine software. The ANN simulates a DTM Vanguard SLS machine available at Fundacio CIM-UPC, Barcelona, while the Selective Laser Melting has been modelled with the parameters and settings used by the Concept Laser M2 machine available at the Mechanical Engineering Lab of the Catholic University of Leuven, Belgium. The extracted models exhibit a build-time prediction error rate lower than 10%, which is a significant improvement compared to conventional parametric methods.· Finally, relational databases have been applied for storing and handling materials information. These databases have been stored as Ms Access data which provides the ease to access, filter, screen and plot the required information. This data can be automatically called and extracted by means of an ODBC call deployed within the Matlab environment.In order to illustrate the functionality of the previous tools put together, a pilot application was designed in Matlab, making use of a number of specialized toolboxes namely: Fuzzy logic, Neural Network, Statistics, Plotting utilities, GUI builder, Database.The result is a prototype system with a graphic user interface divided in three modules: · General design requirements: which deals with those parameters usually defined in the product PDS, for instance: material type, tolerances, surface roughness, geometrical complexity, etc.· Costing module: which makes use of parametric cost estimation and ANN-based models to perform the calculation of cost per part, and for low volumes· Materials selection: Shows the iterative nature of materials selection through screening steps so that the range of suitable options is limited.

Additive manufacturing processes, which utilize selective deposition of material rather than traditional subtractive methods, are very promising due to their ability to build complex, highly specific geometries in short periods of time. Three-dimensional direct inkjet printing is a relatively new additive process that promises to be more efficient, scalable, and financially feasible than others. Due to its novelty, however, numerous technical challenges remain to be overcome before it can attain widespread use. This thesis identifies those challenges and finds that material limitations are the most critical at this point. In the case of deposition of high viscosity polymers, for example, it is found that droplet formation is a limiting factor. Acoustic resonance jetting, a technology recently developed at Georgia Institute of Technology, may have the potential to address this limitation because it generates droplets using a physical mechanism different from those currently in use. This process focuses ultrasonic waves using cavity resonances to form a standing wave with high pressure gradients near the orifice of the nozzle, thereby ejecting droplets periodically. This thesis reports initial exploratory testing of this technologys performance with various material and process parameters. In addition, analytical and numerical analyses of the physical phenomena are presented. Results show that, while the pressures generated by the system are significant, energy losses due to viscous friction within the nozzle may prove to be prohibitive. This thesis identifies and begins evaluation of many of the process variables, providing a strong basis for continued investigation of this technology.

No / This paper reports the results of an investigation into the selective laser sintering of a prealloyed high-speed steel powder. The structured development of processing conditions for single lines, single layers and multiple layers of material is reported, as are the flexural modulus and strength of the single- and multiple layer components. Infiltration with bronze was used to improve the mechanical properties of the components and it is concluded that selective laser sintering of high-speed steel allied to bronze infiltration can produce material with the mechanical properties to allow for use in load-bearing applications, but that further work is required to improve the density, mechanical properties and build rate if selective laser sintering is to develop as a general manufacturing process for hard metals.