El sector textil y confecciones es uno de los sectores con mayores expectativas de crecimiento sostenible de la industria y uno de los que mayor competencia acumula con otros países del sector internacional. Este sector abarca diferentes tipos de procesos, que van desde tratamiento de fibras, hilatura, tejido y confección. El presente análisis recae sobre la baja disponibilidad que presenta los equipos en el proceso de teñido. Este proceso se mide a partir de los reprocesos que existen debido a que se ejecuta mantenimientos correctivos, el cual afecta la producción en el teñido de telas. Asimismo, se logra evaluar el tiempo promedio entre fallas (MTBF) y el tiempo promedio de reparación (MTTR), lo que indica la variabilidad por debajo del objetivo esperado por la organización. Por otro lado, en el tercer capítulo se desarrolla le propuesta de mejora a partir del desarrollo del estado del arte del primer capítulo. Para ello se propone la metodología da seguir de acuerdo con una combinación de RCM y TPM. Bajo esta metodología se desarrolla diferentes actividades y estrategias que permitirán detectar equipos críticos e implementar planes de mantenimiento preventivo mecánico y eléctrico. Además, se incluye como parte de este sistema la implementación de un mantenimiento basado en condición (predictivo) y autónomo. Finalmente, el tercer capítulo finaliza con el soporte de la metodología 5 ‘’S’’ y la evaluación económica a partir de la estructura de costos que tiene prevista el proyecto. Finalmente, en el capítulo cuatro se presenta la validación de la propuesta de mejora a partir de la validación de los resultados en el software Arena. Ello permite concluir que los indicadores MTTR y MTBF ha logrado alcanzar los objetivos presentados en la propuesta. / The textile and garment sector is one of the sectors with the highest expectations of sustainable growth in the industry and one of the sectors with the highest competition with other countries in the international sector. This sector covers different types of processes, ranging from fiber treatment, spinning, weaving and confection. The present analysis falls on the low availability that presents the equipment in the process of dyeing. This process is measured from the reprocesses that exist due to the execution of corrective maintenance, which affects the production of fabric dyeing. Likewise, it is possible to evaluate the average time between failures (MTBF) and the average repair time (MTTR), which indicates the variability below the target expected by the organization. On the other hand, in the third chapter the improvement proposal is developed from the development of the state of art of the first chapter. For this, the methodology to be followed is proposed according to a combination of RCM and TPM. Under this methodology, different activities and strategies are developed to detect critical equipment and implement mechanical and electrical preventive maintenance plans. In addition, the implementation of a maintenance based on (predictive) and autonomous condition is included as part of this system. Finally, the third chapter ends with the support of the 5 '' S '' methodology and the economic evaluation based on the cost structure planned by the project. Finally, chapter four presents the validation of the improvement proposal based on the validation of the results in the Arena software. This allows concluding that the MTTR and MTBF indicators have achieved the objectives presented in the proposal. / Tesis

Submitted by Patrícia Valim Labres de Freitas (patricial) on 2016-03-18T15:56:04Z No. of bitstreams: 1 Diego Damasio de Lima_.pdf: 5804550 bytes, checksum: da0c9850e6394427315ec0b6f28097c5 (MD5) / Made available in DSpace on 2016-03-18T15:56:04Z (GMT). No. of bitstreams: 1 Diego Damasio de Lima_.pdf: 5804550 bytes, checksum: da0c9850e6394427315ec0b6f28097c5 (MD5) Previous issue date: 2016-01-21 / Nenhuma / A atividade de manutenção, seja de equipamentos ou de instalações, é uma função rotineira na maioria das grandes empresas. Entretanto, com o crescimento da automação e da mecanização, aspectos como a confiabilidade e a disponibilidade tornaram-se pontos–chave em termos de competitividade. Isso se dá pelo fato da eventual paralisação das operações ter um impacto nos custos, na qualidade e na confiabilidade dos produtos e serviços. Além de que, o advento da cobrança cada vez maior por qualidade na execução dos serviços, em geral, e do transporte público, em particular. Da mesma forma, essa busca por competitividade precede uma busca incessante por melhores índices de eficiência, seja na empresa pública ou na privada. Este estudo, em particular, tem como objetivo propor um modelo de identificação dos Fatores Críticos de Sucesso (FCS) do sistema de gestão da manutenção da empresa de Trens Urbanos de Porto Alegre S.A. (Trensurb), a fim de reduzir o impacto da atuação da atividade de manutenção no desempenho do negócio da empresa. Ainda na esfera dos objetivos, essa pesquisa construí a estrutura Sistêmica que reflete o modelo do sistema de Gestão da Manutenção da Trensurb, possibilitando a compreensão de que forma as variáveis envolvidas nesse contexto se interelacionam a partir do Pensamento Sistêmico. Ainda construir arquétipos que reflitam a realidade do modus operandi do sistema de gestão da manutenção da Trensurb. E por fim, analisa a estrutura construída de modo a identificar os FCS - Fatores Críticos de Sucesso (FCS) do sistema de gestão da manutenção por meio do Pensamento Sistêmico. Identificamos como por meio do Pensamento Sistêmico (PS) que esse modelo serve como uma alternativa aos modelos usuais de análise da gestão da manutenção. Com a utilização de métodos qualitativos, levanta-se uma série de relações entre as inúmeras variáveis existentes na atuação do sistema de gestão da manutenção. Como resultados foi possível identificar que a área de atuação da equipe de manutenção terceirizada, o modelo de mix de contratação da manutenção própria x terceirizada, a disponibilidade Operacional, e o MKBF - Mean Kilometer Between Failures, correspondem aos Fatores Críticos de Sucesso do sistema de gestão da manutenção da Trensurb. Além disso, foi possível a contrução da tríade da sustentabilidade da manutenção. Sendo conduzido seguindo os preceitos de um Estudo de Caso, a pesquisa evolui no campo de estudo dos fatores críticos de sucesso, não se limitando a apresentar somente uma abordagem pontual, mas evolui através proposição de uma metodologia de levantamento dos Fatores Críticos De Sucesso com o uso do Pensamento Sistêmico. / The maintenance activity is equipment and facilities, is a routine function in most large companies. However, with the growth of automation and mechanization, aspects such as reliability and availability have become key points in terms of competitiveness. This is partly because of the possible shutdown of operations have an impact on costs, the quality and reliability of products and services. Apart from that, the advent of increasingly charging for quality in the execution of services in general and public transport in particular. Similarly, this search for competitiveness precedes a constant search for better levels of efficiency, whether in public or private company. This study, in particular, aims to propose an identification model of the Critical Success Factors (CSF) of the company's maintenance management system Urban Train of Porto Alegre SA (Trensurb) in order to reduce the impact of the performance of maintenance activity on the company's business performance. Even in the sphere of goals, this research built the systemic structure that reflects the model management system Maintenance of Trensurb, allowing us to understand how the variables involved in this context interrelate from Systems Thinking. Still build archetypes that reflect the reality of the modus operandi of the maintenance management of Trensurb system. Finally, it analyzes the structure constructed to identify the FCS - Critical Success Factors (CSF) maintenance management system through Systems Thinking. As identified through the Systems Thinking (PS) that this model serves as an alternative to the usual models of analysis of maintenance management. With the use of qualitative methods, raises a series of relationships between the numerous variables in the performance of maintenance management system. As a result it was possible to identify the area of operation of outsourced maintenance staff, the hiring mix model's own x outsourced maintenance, operational availability, and MKBF - Mean Kilometer Between Failures, correspond to system Success Factors Critical maintenance management of Trensurb. Furthermore, the construction of sustainable maintenance Triad was possible. Being conducted following the precepts of a case study, the research progresses on the critical success factors field of study, not limited to display only a specific approach, but evolves through proposal of a survey methodology for Critical Success Factors with use of Systems Thinking

Maintenance is one area of business that recently has been considered as an activity contributing efficiently to the companies' strategic goals. Understanding the way maintenance could utilise modern technology such as computerised tools or digital data processing is one way to make maintenance profitable. Current research lack appropriate methods for determining data and IT requirements, as well as understanding the way IT could be utilised for enhancing maintenance profitability. This thesis studies and develops tools, methods and theories of how information technology can be utilised for maintenance management in order to reach profitable maintenance. The main research problem is therefore: What are the demands on information technology systems to achieve profitable maintenance? The main problem has been divided into three research questions: RQ1) What are the demands on data and information technology systems for strategic management of maintenance?, RQ2) How can we identify relevant data and information technology systems required to achieve cost-effective maintenance decisions? and RQ3) How can we describe the utilisation of information technology within maintenance? This thesis is based on a systems theory approach, where maintenance is not seen as an isolated activity, but something that interacts, affects and is affected by several other activities, such as production, logistic and quality. Several methods have been used for answering the research questions, but the theory-testing case study method dominates. Main results achieved in the thesis are models and theory for 1) creating a relevant set of data for cost-effective mainte-nance decisions, 2) monitoring the performance of maintenance, suggest invest-ment possibilities and show maintenance contribution on company strategic level, 3) identifying IT systems requirements demanded to achieve profitable maintenance and 4) assessing the IT maturity of a maintenance organisation for the effective utilisation of IT systems. As an illustrative example of computerised maintenance management demands a conceptual decision support model has been developed, which aims at filling the gaps of poor IT coverage for strategic maintenance decision-making. This thesis concludes that the demands of data and IT applications must be connected to the overall maintenance demands, which are reflected in the maintenance goals, purposes and strategy, in order to achieve profitable maintenance. Furthermore, structured methods that ensure the connection between maintenance business goals and data or IT demands are of importance. The ability to make use if IT within maintenance is reflected in the relative IT maturity of the maintenance organisation. Being able to define the IT maturity allows for choosing the most appropriate IT tool to invest in, so that current and future needs of IT support are also covered for with maximum benefit and minimum cost.

Maintenance has evolved over centuries and has played significant role for growth of organizations. Maintenance history is differentiated by three generations, the development of maintenance considered from being “necessary evil” to “profit contributor”. Many literatures have discussed maintenance for optimization and increasing profitability but little on the factors which influence on the future of maintenance. Maintenance should be considered as a “competitive factor” in the future. Many trends have evolved in production and every trend had a major contribution towards production development. The successful implementation of the trends is considered to be a major challenge. Little literatures have talked on the emerging trends and challenges in production. The thesis reviews the historical development of maintenance over generations and presents the key factors which play a major role during the fourth generation, and also identifies the emerging trends and challenges to be faced by production. The literature review, interviews and surveys were used in this thesis. Academic researchers and industrial experts from both maintenance and production department answered the interview and survey questions for this research. The key factors for the proposal of fourth generation of maintenance and the emerging trends and challenges to be faced by production are presented. The result from the research questions and the empirical findings are summarized in a framework that will enable readers to know the historical development of maintenance, the key factors to be considered for the fourth generation of maintenance and the emerging trends and challenges to be faced by production in future. In addition, the thesis also discusses the impact of information technology on the future of maintenance and the effect of sustainability in the future of production.

<p>Background: Generally, operation management includes a set of complicated systems interfacing each other. Most important systems which impact and impacted by the operations management system are production management system and maintenance management system. But to treat the interfacing losses has been difficult as interact and partially overlap each other. In this study, case-operational system was treated with developed model that analysis and design integrated operational system in order to make it easier and cost effective to manage.</p><p>Methods: A model was developed based on latest literature survey work using systems paradigm methodology and systems engineering approach.</p><p>Results: Among five analysis techniques, four types of interfacing losses were identified, seven requirements were extracted, nine conceptual solutions were generated, one of them was selected and based on it the integrated operational management system were designed.</p><p>Conclusions: The results suggest that the operational system in case-company shall be integrated by organization management, process management, and control management, in addition to data management.</p> / <p>Bakgrund: I allmänhet har operations verksamhet en del komplicerade system där friktion kan förekomma. De viktigaste systemen som har påverkan på operations verksamhet är produktion och underhålls system. Att behandla friktions förluster har varit svårt eftersom de både samverkar och delvis överlappar varandra. I dem här studien har olika fall av operationssystem behandlats med att först utveckla en modell, analysera och designa den integrerade operationssystemet för att få den billigaste och dem mest kostnads effektiva sätt att klara av.</p><p>Metod: En modell har utvecklats baserat på de senaste metoderna genom att använda system paradigm metoder och systemtekniska angreppssätt.</p><p>Resultat: Genom att använda fem sätt att analysera, sju bestämmelser extraherade, nio lösningar generade, valdes en av lösningarna och med lösningen som grund designades operations verksamhet.</p><p>Slutsats: Resultatet förslog att operations verksamhet skall integrera organisation, process och kontroll ledningar och inte bara data ledningen.</p>

A majority of utilities conduct maintenance of transmission line components based on the results of routine visual inspection. The inspection is normally done by inspectors who detect defects by visually checking transmission line components either from the air (in helicopters), from the ground (by using high-powered binoculars) or from the top of the structure (by climbing the structure). The main problems with visual inspection of transmission lines are that the determination of the defects varies depending on the inspectors' knowledge and experience and that the defects are often reported qualitatively using vague and linguistic terms such as "medium crack", "heavy rust", "small deflection". As a result of these drawbacks, there is a large variance and inconsistency in defect reporting (which, in time, makes it difficult for the utility to monitor the condition of the components) leading to ineffective or wrong maintenance decisions. The use of inspection guides has not been able to fully address these uncertainties. This thesis reports on the application of a visual inspection methodology that is aimed at addressing the above-mentioned problems. A knowledge-based Fuzzy Inference System (FIS) is designed using Matlab's Fuzzy Logic Toolbox as part of the methodology and its application is demonstrated on utility visual inspection practice of porcelain cap and pin insulators. The FIS consists of expert-specified input membership functions (representing various insulator defect levels), output membership functions (indicating the overall conditions of the insulator) and IF-THEN rules. Consistency in the inspection results is achieved because the condition of the insulator is inferred using the same knowledge-base in the FIS rather than by individual inspectors. The output of the FIS is also used in a mathematical model that is developed to suggest appropriate component replacement date. It is hoped that the methodology that is introduced in this research will help utilities achieve better maintenance management of transmission line assets.

Thesis (MEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The management of physical assets has become a popular eld of study over recent years and is being acknowledged in multiple disciplines world wide. In this project, research on Physical Asset Management (PAM), maintenance and decision making are presented. PAM is a complex subject and requires the participation of multiple disciplines in order to successfully manage physical assets. Moreover, the management of maintenance makes a big contribution in achieving successful PAM. Decision making is a core element to manage maintenance e ciently, both on strategic and operational level. Various methods and techniques can be used to aid the decision making process such as, using past experience, xed decision making techniques and techniques involving numerical calculations, to mention only a few. However, using numerical calculations to make decisions are not very popular. This is due to various reasons, for example the inherent complexity of the mathematics and the time required to execute such calculations are disliked. People tend to avoid complex numerical calculations and rather rely on past experience and discussion of circulating opinions to make decisions. This is not ideal and can lead to inconsistent and inaccurate decisions. In this project, the importance of numerical decision making is researched, especially in maintenance related decisions. The focus is placed on the simpli cation of numerical decision making techniques with the aim to make it easy and quick to use to support operational PAM decisions. Di erent decisions regarding PAM, especially decisions with regards to managing maintenance in order to achieve PAM, are discussed by means of a literature study. This is done to clarify the applicability of using numerical decision making techniques to support this type of decisions. A few di erent available numerical techniques are highlighted that can be used to support the decision making process. The decisions together with numerical decision making techniques are evaluated in order to combine the most appropriate techniques in a simpli ed manner. The purpose of this is that it can be used by anyone with the necessary knowledge of a speci c system or operation. As a result a simpli ed numerical decision making toolbox is developed that can support maintenance related decision. This toolbox is applied to a real life situation by means of a case study, made possible by Anglo American Platinum Limited (Amplats). An evaluation and validation of the toolbox is done through the case study to conclude wether it has value in practice or not. / AFRIKAANSE OPSOMMING: Die bestuur van siese bates het die afgelope paar jaar 'n gewilde studieveld geword en word erken in verskeie dissiplines reg oor die w^ereld. In hierdie projek word navorsing gedoen oor Fisiese Bate Bestuur (FBB), instandhouding en besluitneming. FBB is 'n komplekse onderwerp en vereis die deelname van verskeie dissiplines om sukses te behaal. Die bestuur van instandhouding maak 'n groot bydrae tot suksesvolle FBB. 'n Kern element van doeltre ende instandhouding is besluitneming, beide op strategiese en operasionele vlak. Verskillende metodes en tegnieke kan gebruik word om die besluitnemingsproses te ondersteun soos byvoorbeeld om gebruik te maak van ondervinding en vorige gebeurtenisse, vaste besluitnemingstegnieke, tegnieke wat numeriese berekeninge gebruik en nog meer. Die gebruik van numeriese metodes om besluite te neem is nie baie gewild nie. Dit is as gevolg van verskeie redes soos byvoorbeeld die inherente kompleksiteit en ingewikkeldheid van die wiskunde en ook die tyd wat benodig word om sulke berekeninge uit te voer. Mense is geneig om ingewikkelde numeriese berekeninge te vermy en eerder staat te maak op vorige ervaring en die bespreking van menings om besluite te neem. Dit is nie ideaal nie en kan lei tot onkonsekwente besluite, of selfs verkeerde besluite. In hierdie projek is die belangrikheid van numeriese besluitneming nagevors, veral in die onderhoudsverwante besluite. Die fokus word geplaas op die vereenvoudiging van die numeriese besluitnemings tegnieke. Die doel is om dit op so 'n manier te vereenvoudig dat dit maklik en vinnig is om te gebruik vir operasionele FBB besluite. Verskillende besluite oor FBB, veral besluite met betrekking tot instandhouding om suksesvolle FBB te bereik, word bespreek deur middel van 'n literatuurstudie. Die literatuurstudie ondersoek die toepaslikheid van die gebruik van numeriese besluitnemingstegnieke vir hierdie soort besluite. 'n Paar verskillende beskikbare numeriese tegnieke wat gebruik kan word om die besluitnemingsproses te ondersteun word uitgelig. Die besluite, saam met numeriese besluitnemingtegnieke, word ge evalueer om die mees gepaste tegnieke te kombineer in 'n vereenvoudigde manier. Uiteindelik moet dit deur enige iemand met die nodige kennis van 'n spesi eke stelsel of proses gebruik kan word. As resultaat is 'n vereenvoudigde numeriese besluitnemingstegniekkombinasie ontwikkel wat besluite verwant aan instandhouding kan ondersteun. Hierdie tegniek-kombinasie word toegepas in 'n werklike situasie deur middel van 'n gevallestudie, wat moontlik gemaak is deur Anglo American Platinum Limited. 'n Evaluering en validering van die tegniek-kombinasie word gedoen in die gevallestudie om te bepaal of dit wel waarde het in die praktyk of nie.

Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: It has been postulated that lean thinking principles can be successfully applied to any industry. Following on that postulation, there have been great advances in the area of lean thinking outside the “traditional” domain of manufacturing. One such advancement has been in the area of maintenance operations where lean thinking has been used through the concept of lean maintenance. However, a problem lies in the fact that the work that has been done so far has been largely limited to the manufacturing environment where lean maintenance is practised as a prerequisite for lean manufacturing. Little evidence exists of the use of frameworks or models that can test, let alone apply, lean thinking in operational maintenance environments outside of the manufacturing context. The main objective of this research was to come up with a framework, based on lean thinking tools and relevant performance measures, which will prove the applicability or otherwise, of lean thinking in an operational maintenance environment outside the traditional domain of manufacturing. A case study of the rolling stock section of the Salt River depot of PRASA, Metrorail, which is a typical non-traditional domain for lean thinking, was used to build and verify the framework. The Analytic Hierarchy Process (AHP) together with the Quality Function Deployment (QFD) process, is used in building and quantifying the judgements made in developing elements of the framework. The Value Stream Management process is used to predict the possible outcomes of using the proposed framework in the case study. The study was based on the hypothesis that lean thinking can also be applicable to non-manufacturing oriented maintenance organisations. The ensuing framework is used to make the argument for the use of the lean thinking approach in non-manufacturing oriented maintenance environments and hence expand the body of knowledge in this subject area. It also provides a roadmap for PRASA, Metrorail and other similar maintenance organisations in the rail industry to streamline and improve current operations through value addition and waste elimination efforts. / AFRIKAANSE OPSOMMING: Daar word bespiegel dat die beginsels van besparende denke (“lean thinking”) suksesvol toegepas kan word op enige industrie. As gevolg van hierdie hipotese is daar groot vooruitgang op die gebied van besparende denke buite die “tradisionele” gebied van vervaardiging. Een sodanige vooruitgang is op die gebied van die verrigting van instandhouding waar besparende denke bekend is as die konsep van “lean maintenance”. Die problem is dat die vooruitgang tot dusver beperk is tot die vervaardigingsomgewing waar besparende instandhouding beskou word as ‟n vereisde vir besparende vervaardiging. Daar word min gebruik gemaak van raamwerke of modelle om besparende denke te toets of om dit toe te pas in instandhoudingsomgewings buite die vervaardigingskonteks. Die hoofdoelwit van hierdie navorsing is om te vore te kom wet ‟n raamwerk wat gegrond is op besparende denke en relevante prestasie maatstawwe, en wat die toepaslikheid van besparende denke , al dan nie, op die verrigting van instandhouding buite die tradisionele gebied van vervaardiging sal bewys. ‟n Gevalle studie van die Soutrivier Depot van PRASA Metrorail, wat tipies is van ‟n nie-tradisionele gebied vir besparende denke, is gebruik vir die bou en stawing van die raamwerk. Die analitiese hiëragiese proses (AHP) tesame met die kwaliteits funksionele ontplooiing (QFD) proses word gebruik in die kies van elemente vir die raamwerk. Die waarde stroom bestuursproses word gebruik om die moontlik uitkomste van die gebruik van die voorgestelde raamwerk, te voorspel. Die studie is gegrond op die hipotese dat besparende denke ook toegepas kan word op nie-vervaarding-georienteerde instandhoudingsorganisasies. Die raamwerk word gebruik om te bewys dat die besparende denke benadering gebruik kan word in nie-vervaardiging–georienteerde instandhoudingsomgewings en dus kennis hieroor uit te brei. Die raamwerk kan ook gebruik word as ‟n padkaart deur Metrorail en ander soortgelyke instandhoudingsorganisasies in die spoorweg industrie, om hulle huidige werksverrigting deur waarde toevoeging te verbeter en om verkwisting te voorkom.

This study was conducted in a metallurgical company, a manufacturer of products with a production process with high precision equipment requiring effective maintenance to maintain the quality of the production process. The aim was the implementation of a maintenance management model based on Total Productive Maintenance - TPM in a production line of the company. To reach the proposed objective, we conducted an applied research, quantitative technique with the use of case study. Has been proposed the model for conducting the activities, emphasizing the training activities of the teams involved in the implementation, collection and analysis of indicators of industrial performance a year before the implementation of TPM. The development followed the timetable of activities and after application of the model of maintenance management, the results of these performance indicators were collected again. We observed that after the implementation of TPM, the indicators of industrial performance improvement and discussed incorporated positive trends for the following periods. Thus, it is concluded that the TPM assists in improving industrial performance and competitiveness of the production line studied. / Este trabalho foi realizado em uma empresa metal-mecânica, fabricante de produtos que apresentam um processo de produção com equipamentos de alta precisão e que necessitam de manutenção eficaz para manter a qualidade do processo produtivo. O objetivo foi a implantação de um modelo de gestão da manutenção baseado na Manutenção Produtiva Total TPM em uma linha de produção da empresa. Para atingir o objetivo proposto, foi realizada uma pesquisa aplicada, de natureza quantitativa com a utilização da técnica de estudo de caso. Foi proposto um modelo de condução das atividades, salientando as atividades de capacitação das equipes envolvidas na implantação, a coleta e análise dos indicadores de desempenho industrial de um ano antes do início da implantação da TPM. O desenvolvimento das atividades seguiu o cronograma e após a aplicação do modelo de gestão da manutenção, os resultados dos mesmos indicadores de desempenho foram coletados novamente. Observou-se que após a implantação da TPM, os indicadores de desempenho industrial analisados apresentaram melhoria e tendências positivas para os períodos seguintes. Assim, conclui-se que a TPM auxilia na melhoria do desempenho industrial e da competitividade da linha de produção estudada.

Made available in DSpace on 2014-12-17T14:52:58Z (GMT). No. of bitstreams: 1 RobertoKMF_DISSERT.pdf: 1712911 bytes, checksum: 4a2d9da3d58d19eb0b246c2f5c1cf027 (MD5) Previous issue date: 2010-12-22 / This work searches to offer a model to improve spare parts stock management for companies of urban passenger transport by bus, with the consequent progress in their maintenance management. Also known as MRO items (Maintenance, Repair and Operations), these spare parts, according their consumption and demand features, cost, criticity to operation, lead-time, quantity of suppliers, among other parameters, shouldn?t have managed their inventory like normal production items (work in process e final products), that because their features, are managed by more predictable models based, for example, in economic order quantity. In the case specifically of companies of urban passenger transport by bus, items MRO have significant importance in their assets and a bad management of these inventories can cause serious losses to company, leading it even bankrupticy business, in more severe situations which missing spare part provokes vehicles shutdown indefinitely. Given slight attention to the issue, which translates in little literature available about it when compared to that literature about normal items stocks, and due the fact that MRO items be critical to bus urban transport of passengers companies?, it is necessary, so, deepen in this theme searching to give technical and scientific subsidies to companies that work, in many times, empirically, with these so decisive inputs to their business. As a typical portfolio problem, in which there are n items, separated into critical and noncritical, while competing for the same resource, it was developed a new algorithm to aid in a better inventory management of spare parts used only in corrective maintenance (whose failures are unpredictable and random), by analyzing the cost-benefit ratio, which compares the level of service versus cost of each item. The model was tested in a company of urban passenger transport by bus from the city of Natal, who anonymously provided their real data to application in this work / O trabalho busca oferecer um modelo para melhor gest?o do estoque de pe?as de reposi??o para empresas de transporte urbano de passageiros, com a conseq?ente melhoria na gest?o das suas manuten??es. Tamb?m conhecidos como itens MRO (Manuten??o, Reparo e Opera??es), estas pe?as de reposi??o, em fun??o das suas caracter?sticas de consumo e demanda, custo, criticidade para a opera??o, tempo de ressuprimento, quantidade de fornecedores, entre outros par?metros, n?o devem ter seus estoques geridos como itens normais de produ??o (bens intermedi?rios e produtos acabados), que pelas suas caracter?sticas, s?o regidos por modelos mais previs?veis baseados, por exemplo, no lote econ?mico de compra. Em se tratando especificamente de empresa de transporte urbano de passageiros por ?nibus, os itens MRO t?m peso significativo nos seus ativos e a m? gest?o deste estoque pode causar s?rios preju?zos ? companhia, levando-a, em situa??es mais graves em que a pe?a faltante resulte em parada de ve?culos por tempo indeterminado, at? ? fal?ncia do neg?cio. Face ? discreta aten??o ao tema, o que se traduz na pouca literatura dispon?vel sobre o mesmo quando comparada ?quela relacionada aos estoques de itens de produ??o, e devido ao fato dos itens MRO serem cr?ticos para as empresas de transporte urbano de passageiros, faz-se necess?rio, pois, o aprofundamento no assunto buscando dar subs?dios t?cnico-cient?ficos ?s firmas que trabalham, muitas vezes de forma emp?rica, com estes insumos t?o decisivos para o seu neg?cio. Tendo-se um t?pico problema de portf?lio, no qual existem n itens, segregados em cr?ticos e n?o-cr?ticos, competindo simultaneamente pelo mesmo recurso, foi desenvolvido um novo algoritmo para auxiliar na melhor gest?o do estoque de pe?as de reposi??o utilizadas somente em manuten??es corretivas (cujas falhas s?o imprevis?veis e aleat?rias), atrav?s da an?lise da rela??o custo-benef?cio, onde comparam-se n?vel de servi?o versus custo de cada item. O modelo foi testado em uma empresa de transporte urbano de passageiros por ?nibus da cidade de Natal, que anonimamente, forneceu seus dados reais para aplica??o neste trabalho