Submitted by admin tede (tede@pucgoias.edu.br) on 2017-08-21T12:30:58Z No. of bitstreams: 1 Celso Aurélio de Morais Lima.pdf: 2546394 bytes, checksum: 8a8908066e6f60ae202da67d1738b90d (MD5) / Made available in DSpace on 2017-08-21T12:30:58Z (GMT). No. of bitstreams: 1 Celso Aurélio de Morais Lima.pdf: 2546394 bytes, checksum: 8a8908066e6f60ae202da67d1738b90d (MD5) Previous issue date: 2017-04-27 / The main objective of this dissertation is to develop a reliability assessment applied to reparable systems in the sugar and alcohol industry. The work has a quantitative approach with a combined research method: simulation modeling with case-study. Therefore, a dynamic modeling is used to develop a case-study. For this, a Non- Homogeneous Markov Process (PNHM) model is used to represent the states transitions (operation-maintenance) of sugar centrifuges, in order to obtain reliability indicators. Integrated to the PNHM model, it will be used the Generalized Renewal Process (PRG) to describe the probabilities of failures considering imperfect repairs. The PRG is defined according to the parameters of scale, shape and rejuvenation (α, β, q), which are estimated by Bayesian Inference. In the development of the case-study, the data collection of centrifugal failures was performed and, through the simulation of the hybrid model, the case-study was conceived. The estimated availability for 5640 hours was 93.23%, whose the other 7% represents maintenances moments. For 323 hours of simulation, the reliability resulting was 50%, demonstrating high system susceptibility to failures. The results suggest the revisions of the intervals defined for preventives maintenances, which should be applied to the most observed failure mode, called malfunction of the sensing systems. / O principal objetivo desta dissertação é desenvolver uma avaliação de confiabilidade aplicada a sistemas reparáveis, na indústria sucroalcooleira. O trabalho possui abordagem quantitativa com método de pesquisa combinado: modelagem de simulação com estudo de caso. Portanto, utilizar-se-á de uma modelagem dinâmica para desenvolver um estudo de caso. Para isso, aplicar-se-á um modelo de Processos Não Homogêneos de Markov (PNHM) para representar as transições entre estados (operacional-em manutenção) das centrífugas de açúcar, visando obter indicadores de confiabilidade. Integrado ao modelo PNHM, será utilizado o Processo de Renovação Generalizado (PRG) para descrever as probabilidades de falhas considerando reparos imperfeitos. O PRG é definido em função dos parâmetros de escala, forma e rejuvenescimento ( ,!,"), que serão estimados via Inferência Bayesiana. No desenvolvimento do estudo de caso, realizou-se a coleta de dados de falhas das centrífugas e, por meio da simulação do modelo híbrido, o estudo de caso foi concebido. A disponibilidade estimada para 5640 horas foi de 93,23%, sendo os 7% complementares referentes a manutenções. A confiabilidade apresentada foi de 50% para 323 horas, demonstrando alta suscetibilidade do sistema à falhas. Os resultados sugerem revisão nos intervalos definidos para manutenção preventiva, as quais deverão ser dedicadas ao modo de falha mais observado, denominado mal funcionamento dos sistemas de sensoreamento.

The Diploma thesis is focused on possibilities of an assessment of a hydraulic switchboard and its manufacturing process. Furthermore, it analyses methods individually which are suitable for quality assurance and production reliability, which are described in details. The follow-up work focuses more on the Statistical Process Control (SPC) method which is applicable in the early warning system and the Failure mode, effects, and criticality analysis (FMECA) method, applicable in the planning system. These two methods are further applied to the newly introduced process of machining the hydraulic switchboard as an effective tool not only for assessing the reliability of production, but also for its subsequent securing and maintaining in a relevant condition.

The subject of the diploma thesis Assessment of the reliability of a selected process in a non-manufacturing company is the analysis of the reliability of processes and their risks. The partial goals were to perform a professional literature search of valid standards and a system analysis concerning the issue of assessing the reliability of the selected process. The first part of the diploma thesis deals with the approach to selected concepts and tools that are used in this work. Furthermore, the author dealt with selected requirements of the relevant standards ČSN EN ISO 9001:2016, ČSN EN ISO 14001:2016 a ČSN ISO 45001:2018, which relate to the issues addressed. The practical part introduces the company, especially the division of the company related to the process. Subsequently, the process was processed into an integrated flowchart and assessed using quality tools, namely FMEA analysis and Internal Audit. Based on the results obtained using these tools, the analysis revealed relevant risks and findings. In the last part, the author compared and summarized the results of the assessment and the identified findings, for which he proposed appropriate preventive measures to improve the selected process. Finally, the own conclusions and proposed preventive measures are discussed.

O objetivo do presente trabalho de pesquisa é o desenvolvimento de uma metodologia de monitoramento e detecção de defeitos esporádicos e de difícil diagnóstico, bem como o estudo de caso de sistemas de ignição de motores de combustão interna do ciclo Otto. O estudo visa aumentar a robustez do sistema perante falhas esporádicas de difícil detecção, reduzindo drasticamente o tempo de determinação da origem da falha. Através de testes acelerados e simulados em bancadas, a metodologia indica o estado atual dos componentes do sistema de ignição no tocante ao potencial de ocorrência de falhas esporádicas que afetam a combustão e também a confiabilidade do veículo. Os componentes e sistemas objetos da pesquisa são identificados por meio de um processo de análise de risco e de fatores como: ocorrência de muitos anos de histórico de campo, indicadores de reparos repetitivos, falhas esporádicas e de difícil diagnóstico, quebras de qualidade e do comportamento do sistema de diagnóstico OBD Br-2 (On-Board Diagnostic versão 2) diante de falhas intermitentes. A metodologia também proporciona uma ferramenta de análise de interfaces de componentes, que são fontes de falhas potenciais nem sempre consideradas nos processos de análise. Por meio de testes acelerados desses componentes críticos, é proposta metodologia para análise e correção imediata do processo produtivo de tais componentes, culminando na melhoria da confiabilidade dos processos críticos. A metodologia visa a aumentar a robustez do sistema de ignição, detectando rapidamente potenciais falhas esporádicas de difícil diagnóstico oriundas dos processos de fabricação e corrigindo-as imediatamente, introduzindo, assim, um fator de confiabilidade a um componente ou a um processo crítico cuja criticidade era até então desconhecida. Tal criticidade passa a ser gerenciada com impacto positivo nas emissões de poluentes e na confiabilidade global do conjunto. / The objective of this research work is the development of a methodology to monitor and identify sporadic and difficult to detect failures as well as present a case study on the ignition system of internal combustion engines. Such study aims to increase the system reliability. It also helps to reduce dramatically the time to define the failure root cause. Using accelerated test benches, the methodology will indicate the current situation of the components related to the potential of intermittent failure occurrence which affect the combustion and vehicle reliability. The components and systems of this study are identified by a process risk analysis as well as factors like: occurrence time history, repetitive repair index, sporadic and difficult to detect failures, quality breakdown index, and the behavior of the OBD-2 diagnostic system (On-Board Diagnostic version 2) The methodology will also provide a tool to analyze the components interfaces. Such interfaces are a source of potential failures but are not considered in the analysis process. By means of accelerated tests of such critical parts it will be proposed an analysis methodology and a prompt interference at the production process, increasing the reliability of the critical processes. The methodology aims the system robustness increase of the ignition system detecting very fast the sporadic failure potential on the manufacturing process. By introducing a reliability degree of a component or process it will be managed with a benefic impact on emissions and overall reliability of the ignition system.

Effiziente und zuverlässige Prozesse sind für die Produktion und das Verpacken von Verbrauchsgütern wie Lebensmittel aufgrund enorm hoher Produktionsmengen von großer Bedeutung. Auch im Getränkebereich steigt der Kostendruck und rückt die Bedeutung effizienter Prozesse in den Vordergrund. Mit systematischer Analyse des Betriebsverhaltens der Anlagen gelingt es, die technischen und organisatorischen Potenziale besser zu nutzen und die Gesamteffektivität der Produktion zu erhöhen. / Efficient and reliable processes for production and packaging are of great importance for high production quantity of consumer goods like food. Especially in the beverage industry the cost pressure is increasing, that’s why the significance of efficient processes gets more and more important. The systematic analysis of the operating behavior of machine equipment helps to find technical and organizational potential to increase the overall effectiveness of the production.