Este trabalho trata da avaliação do desempenho de máquinas de usinagem cujas arquiteturas se baseiem em estruturas cinemáticas paralelas planas. Inicialmente analisa dois tipos distintos de arquiteturas paralelas, avaliando as suas mobilidades, possíveis formas de atuação, além de apresentar seus modelos teóricos cinemáticos e dinâmicos correspondentes. A seguir, descrevem-se no texto algumas simulações realizadas em oito modelos propostos, de modo a se observar os comportamentos das arquiteturas consideradas, quando da execução de possíveis trajetórias da ferramenta em movimento plano (2D). A seleção dos modelos e a discussão dos resultados são guiadas por índices de desempenho presentes na literatura e outros propostos ou adaptados. O trabalho discute ainda as melhores soluções, com foco nas trajetórias prédefinidas e em critérios importantes para os mecanismos de arquitetura paralela. / This dissertation concerns the performance evaluation of machine-tool with architectures based on planar parallel kinematic structures. The text starts analyzing two distinct types of parallel architectures, their mobility, feasible schemes of actuation and presents their kinematic and dynamic models. From this point, simulations are described to figure out some characteristics of chosen architectures, in eight different models, focused on execution of tool trajectories in plane motion (2D). The model selection and the discussion about obtained results are guided by performance indexes from the literature and others either proposed or adapted. The work also discusses the best solutions, for pre-defined tool trajectories and important points for mechanisms with parallel structures.

A obsolescência das Máquinas-Ferramentas (MFs) é um processo natural de envelhecimento neste tipo de equipamento. Esse processo compreende uma série de degradações tecnológicas, os quais se instalam e ocorrem em toda estrutura física de uma MF, independentemente da tecnologia utilizada. As degradações podem, no entanto, ser resultantes de vários fatores, como uso, aplicação, regime de trabalho, dentre outros. Os aspectos tecnológicos ficam mais evidentes quando se analisam as máquinas a Comando Numérico Computadorizado (CNC). Por sua vez, o CNC é um equipamento que apresenta uma evolução constante, mas que muitas vezes não pode ser facilmente incorporado às máquinas já existentes sem um processo de retrofitting anteriormente definido. Um processo de retrofitting pode ser considerado como um processo que permite aplicar incrementos tecnológicos em uma MF. Mais recentemente, diversos estudos têm apresentado tendências que fazem uma ligação entre MFs e sustentabilidade, sem, no entanto, definir ou propor modelos. Estudar os aspectos do comportamento das MFs existentes e poder aplicar recursos das novas tecnologias pode contribuir para melhorar os aspectos de sua produtividade e, por conseguinte, contribuir para uma produção mais sustentável. No entanto, isso deve ser feito a partir de uma metodologia que oriente um processo de tomada de decisão. Dessa forma, este trabalho propõe um método de referência aplicado a retrofitting de máquinas a partir da definição de coeficientes e de índices numéricos cujos resultados atuam como ferramenta orientativa a um processo de tomada de decisão. O método é aplicado a diversos tipos de MFs e os resultados indicam a viabilidade ou não de um retrofitting. / The obsolescence of Machine Tools (MT) may be defined is a natural process of aging in this type of equipment. This process comprises a series of technological degradation, which settles and occurs across the entire and physical structure of a MT, regardless of the technology used. The degradations may, however, be due to several factors such as usage, application, machining process and so on. The technology aspects are more evident when analyzing the machines Computerized Numerical Control (CNC). By the other hand the CNC is an equipment which naturally contributes with a constant evolution, but they often cant be easily incorporated into an existing machine without a procedure for retrofitting previously defined. A process of retrofitting can be defined and considered as a process incorporates technology resulting in increments of technology to a MT. However, the addressing of such process is usually applied without any models or tools within a process of decision making. More recently, several studies have shown trends making a connection between MT and sustainability without, however, defining templates for such process. The studies of all aspects of the behavior of an existing MT, even with its limitations, suggest the resources of new technologies can help to improve in general all aspects of their productivity and therefore contribute to a more sustainable production. However, this must be done from a methodology that guides the process of decision making. This decision process represents a process that results from a technological gain in a MT or not. Thus, this work proposes a reference method applied to retrofitting machines by defining a series coefficients and numerical indices whose results intends to be used as a tool for helping a decision-making process.

Como seguir com o crescimento da indústria, da economia e do consumo de energia de forma sustentável? No setor manufatureiro as máquinas-ferramentas são peças-chave nos processos de fabricação. Como saber se uma bomba, um motor ou outro elemento acessório é adequado para uma máquina-ferramenta específica? Normalmente, fabricantes se baseiam em sugestões dos fornecedores para selecionar tais elementos, o que resulta em um projeto ajustado pela experiência e por estimativas subjetivas, às vezes superestimando as dimensões do projeto por segurança. O objetivo deste trabalho é monitorar o consumo da energia elétrica durante a fase de uso da máquina-ferramenta, com o fim de explicar a demanda de energia em cada uma de suas tarefas, sugerindo diretrizes para o aperfeiçoamento do projeto desta nos seus componentes críticos. Esta dissertação apresenta uma cuidadosa revisão de livros e pesquisas anteriores, os quais direcionaram a etapa experimental. Assim, elegeu-se trabalhar em um centro de usinagem, o qual foi monitorado por um analisador de qualidade de energia. A metodologia experimental iniciou-se com a avaliação da eficiência energética da máquina-ferramenta em termos de fator de potência, a fim de trabalhar dentro dos parâmetros da legislação brasileira, e finalizou-se com o monitoramento do consumo de energia elétrica. Tal monitoramento foi feito em três cenários de usinagem: em vazio, a seco e com fluido, utilizando um mesmo plano de trabalho em todas as situações. Conclui-se que prognósticos de consumo de energia são possíveis se tempos e constantes do modelo apresentado são conhecidos para uma máquina-ferramenta específica, parâmetros que são influenciados pela experiência do operador. A medição do consumo de energia da máquina em vazio e com remoção permitiram conhecer o consumo de energia pela usinagem propriamente dita. Observou-se também que apenas a máquina-ferramenta consome 59% da energia total quando está usinando; as mudanças de velocidade não afetam o consumo de energia diferentemente da taxa de remoção de material; elementos auxiliares à usinagem não deterioram a eficiência energética da máquina, embora possam representar uma boa taxa percentual de gasto no consumo total; e a troca de ferramentas é mais eficiente na usinagem do que em vazio. / How to follow the growth of industry, economy and energy consumption in a sustainable way? In the manufacturing sector, the machine tools are key-parts in the processes. How can we know if a pump, an electric motor or another accessory element is adequate to a specific machine tool? Usually, the manufacturer relies on suggestions from suppliers to select those elements, resulting in a project adjusted by experience and subjective estimations, sometimes overestimating for security. The objective of the present work is to monitor the consumption of electric power during the useable phase, in order to map the energy demand in each of its tasks, thus suggesting guidelines for the improvement of the project to its critical components. This dissertation presents a thorough review of books and previous research, which has guided the experimental phase. Accordingly, it was chosen to work in a machining center, which was monitored by a power quality analyzer. The experimental methodology began with the evaluation of the energetic efficiency of the machine tool in terms of power factor, in order to work within the parameters of the Brazilian legislation, and ended up with electric energy consumption monitoring. Such monitoring was made in three machining scenarios: cutting air, cutting dry and with coolant, sing the same CNC workplan in all situations. The conclusions include that forecasting of energy consumption is possible if time and constants of the proposed model are known for a specific machine tool, parameters which are influenced by the experience gathered by the operator. The measurement of energy consumption during air cutting and removing material allowed to know the energy consumption of the machining operation itself. It was also observed that: the machine alone consumes 59% of the total energy when in operation; the energy consumption is not affected by speed changes, but by the material removal rate; auxiliary elements to the machining do not negatively affects the energy efficiency of the machine, although may represent considerable expenditure in total consumption; and, the exchange of tools is more efficient when removing material, than when air machining.

Under greatly improvement in manufacturing quality and R¡®D capacity, Taiwanese Machine Tool Industry gradually emerging on the international and saturated domestic market in recent years. Also, domestic market is gradually saturated; machine tool manufacturer is forced to move out of Taiwan. It also caused Taiwan tool industry to internationalize and step into the phase of international market management. Most enterprise scale of Taiwan machine tool industry belong to small and medium-sized ones. Under limited resource, it is a critical issue to allocate the resource efficiently and to control the key success factors of international marketing management. This research use publicly listed machine tool industry companies in Taiwan to be the study object. First, besides collecting related literatures in domestic and overseas, this research also used questionnaire and interviewees to study the key success factors of Taiwanese Machine Tool Industry international market management, by conclude the following four factors, which were entire environment, industrial structure, business competitive advantages and international market strategy. Secondly, the AHP (Analysis Hierarchy Process) will be used as analysis method to evaluate the importance of key success factors in Taiwanese Machine Tool Industry international market management. Finally, the results showed that the most important five factors of the key success factors in Taiwanese Machine Tool Industry international market management were: 1) Enterprise's brand/Business goodwill; 2) Tax reduction policy; 3) Global marketing networks management; 4) Key components of self-control and 5) The impact of the international environment. The weight ratio of factors could provide the Taiwanese Machine Tool Industry as the index for operating in foreign markets

Selection of the right machine tools is an important decision for most manufacturing companies. The quality and efficiency of manufacture are affected by the correct adoption of machine and equipment, and it will result in reducing the cost, increasing the production, and enhancing the flexibility for the diverse type of machining parts in this competitive globalized environment. On the contrary, an incorrect selection can retard the productivity of company. This research presents the procedures of AHP method for selecting 4-axis CNC machining centers including searching the literature of selecting machines, consulting experts with abundant experience of machine tool, translating the unstructured and biased commercial specification to the objective and hierarchical evaluation criteria for selecting machines. In order to experiment the applicability of the AHP model as well as to realize the relative importance of the criteria for the mold design and manufacturing company, a company was invited as the survey objective. This method proposed in this research is general in form and can be applied to the selections of other machine tools for other manufacturing industries. Also, it is hoped that the results of this experimental study will provide a reference for the domestic machinery manufacturing company to develop 4-axis CNC machining centers.

The credit card industry is huge with over two and a half billion cards shipped annually. A local card manufacturer, with a production volume in excess of forty million cards annually, approached the University of Canterbury to design and develop advanced card manufacturing technology. The motivation behind this development was the desire of the sponsoring company to keep abreast of new technologies and to have the ability to manufacture and supply cards with this new and emerging technology into a highly competitive world market. This thesis reports the research surrounding the development of a dedicated new machine tool explicitly designed to implement the emerging technologies found in the international credit card industry. The machine tool, a dedicated milling machine, was not developed in its entirety within these pages; however, three major constituents of the machine were researched and developed to a point where they could be implemented or become the subject of further research. The three areas of interest were; • A machine table system that avoided the increased zonal wear to which linear bearings are subject, typically due to short high frequency traversals, and also the high friction and mass generally found in dovetail slides. • Design requirements demanded the use of a single commercially available carbide cutter to produce 1500 components per hour. Therefore, a purpose built high (revs per minute) rpm spindle and drive system specifically for use with polymeric materials, (R-PVC in particular) was deemed necessary. • Tracking the cutter depth in relation to an RFID aerial track embedded within the credit card core. The aerial tracking was to be dynamic and occur during the machining process with the machine “remembering” the depth of cut at contact with the aerial. Each of the three areas was researched via an in-depth literature review to determine what and if any material had been published in these fields. For the development of the machine table a novel flexure hinge idea was considered. Considerable material was discovered about flexures, but very little was found to be relevant to the application of high displacement metal flexures necessary to meet the required levels of table movement. In effect the proposed machine table system and research in this field would be novel. The high performance spindle investigation became directed into a much narrower focus as it progressed; that of determining the power consumption required to machine the integrated circuit pockets in an R-PVC work piece. This was due to the lack of information pertaining to the physical properties of polymeric materials, in particular the specific cutting pressure. The depth following sensor array was configured using capacitance detection methods to determine the distance between the cutter?s end and the aerial tracks. Capacitance sensing methods, whilst not new, were developed into a novel arrangement to meet the specific cutter tracking requirements of the proposed new machine tool. Each of the respective development areas had concept designs completed and were prototyped before being tested to determine the effectiveness of the respective designs. The outcomes from the testing are reported herein, and show each constituent part to be basically feasible, in the application. The results were sufficient to indicate that each development showed distinct potential but further development and integration into the machine tool should ensue.

With technology changing at a dramatic pace, entrepreneurs may assume that acquiring the newest production equipment available is the best option. But that is not always the case. It is important to first assess the needs in order to decide whether new or remanufactured production equipment is the best alternative. Investment on production equipment can be initiated due to existing equipment cannot handle capacity; products evolve and changes needed to meet market requirement; to continuously improve production system; or the general requirements for quality, environment, economy and safety. However, the study reveals that it has received only limited attention from academics and practitioners regarding to whether decide to remanufacture or new acquire production equipment. Further, the framework visualizes the complexity of managing decision-making between production equipment remanufacturing and new acquisition. The study employs qualitative method by conducting literature review, interviews, brainstorming sessions, benchmarking, and observation to build the theoretical framework and collect empirical data. The thesis identifies the differences between production equipment remanufacturing and new acquisition; distinguishes the different levels of production equipment, proposes a new definition of production equipment remanufacturing; and analyses factors should be considered for the decision-making process. Altogether, the findings provide strong evidence to propose a decision-making checklist in decisions between production equipment remanufacturing and new acquisition.

In this study, a three-axes PC numerical control system for industrial applications has been developed. With this system, fast and cheap prototyping of designed objects can be realized. The system consists of software and a hardware which includes an XYZ positioning table and three step motors controlling this table. A proper drive circuit for the stepper motors is utilized. The software digitizes two dimensional drawings of three dimensional objects and generates the control signals for the XYZ positioning table. The software is developed under Microsoft Studio Visual Basic 6.0 environment regardless of the OS of the PC. The parallel port of the PC has been utilized for generating the necessary control signals for the stepper motors.

In this study, the new predictive model for the micro-grinding process was developed by consolidating mechanical and thermal effects within the single grit interaction model at microscale material removal. The size effect of micro-machining was also included in the proposed model. In order to assess thermal effects, the heat partition ratio was experimentally calibrated and compared with the prediction of the Hahn model. Then, on the basis of this predictive model, a comparison between experimental data and analytical predictions was conducted in view of the overall micro-grinding forces in the x and y directions. Although there are deviations in the predicted micro-grinding forces at low depths of cut, these differences are reduced as the depth of cut increases. On the other hand, the optimization of micro machine tools was performed on the basis of the proposed design strategy. Individual mathematical modeling of key parameters such as volumetric error, machine working space, and static, thermal, and dynamic stiffness were conducted and supplemented with experimental analysis using a hammer impact test. These computations yield the optimal size of miniaturized machine tools with the technical information of other parameters.

Condition monitoring of critical machine tool components and machining processes is a key factor to increase the availability of the machine tool and achieving a more robust machining process. Failures in the machining process and machine tool components may also have negative effects on the final produced part. Instabilities in machining processes also shortens the life time of the cutting edges and machine tool. The condition monitoring system may utilise information from several sources to facilitate the detection of instabilities in the machining process. To avoid additional complexity to the machining system the use of internal sensors is considered. The focus in this thesis has been to investigate if information related to the machining process can be extracted directly from the internal sensors of the machine tool. The main contibutions of this work is a further understanding of the direct response from both linear and angular position encoders due the variations in the machining process. The analysis of the response from unbalance testing of turn tables and two types of milling processes, i.e. disc-milling and slot-milling, is presented. It is shown that operational frequencies, such as cutter frequency and tooth-passing frequency, can be extracted from both active and inactive machine axes, but the response from an active machine axis involves a more complex analysis. Various methods for the analysis of the responses in time domain, frequency domain and phase space are presented. / QC 20100518