Productivity advances generated from ‘lean manufacturing’ are self–evident. Plants that adopt ‘lean’ are more capable of achieving shorter lead times, less waste in the system and higher quality levels. The goal of this study was to ascertain which ‘lean’ tools and techniques are available for use. A matrix was constructed with a summation of the authors who agree that specific ‘lean’ tools will reduce cycle time. It was found that reduced set–up time and waste elimination are most affected by the implementation of ‘lean’ tools and techniques. An empirical study was conducted to confirm the results of the literature study. The respondents’ knowledge on the ‘lean’ tools was also tested. It was found that respondents have a sound understanding of set–up time; they agree that it must be reduced in the plant. Pre–scientific evidence and the response from the empirical study confirm that there is a substantial amount of waste in the factory. A current state value–stream map was drawn from a single welded part Product X. The value–stream was analysed to reduce the cycle time in the process, with the focus on set–up time reduction and waste elimination. The future state value–stream map was drawn, displaying astonishing results. A continuous improvement (kaizen) programme will help reduce the cycle time even further by making use of the other ‘lean’ tools discussed in this study. This programme forms part of the procedure to optimise cycle time. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2012.

The application of Statistical Process Control (SPC) to software processes has been a challenging issue for software engineers and researchers. Although SPC is suggested for providing process control and achieving higher process maturity levels, there are very few resources that describe success stories, implementation details, and implemented guidelines for applying SPC to specific metrics. In this thesis the findings of a case study that is performed for investigating the applicability of SPC to software metrics in an emergent CMM Level 3 software organization are presented. As being one of the basic and most sophisticated tools of SPC, control charts are used for the analysis. The difficulties in application of Statistical Process Control to a CMM Level 3 organization are observed by using the existing data of defect density, rework percentage, productivity and review performance metrics and relevant suggestions are provided for dealing with them. Finally the analysis results are summarized and a guideline is prepared for software companies who want to utilize control charts by using their existing metric data.

O controle de perdas tem sido apontado como uma das principais estratégias para melhoria do desempenho e para redução de custos de sistemas de produção. Entretanto, apesar de sua importância, este é um tema pouco abordado na literatura sobre gestão da construção, principalmente no que se refere a sistemas de controle da produção. Alguns estudos recentes chamaram a atenção para a existência de uma perda típica do setor, denominada de making-do, a qual pode ser definida como a redução de desempenho do sistema produtivo devido à execução de atividades em condições subótimas. Este tipo de perda ainda tem sido apontada como uma das causas fundamentais de problemas da qualidade, e de outras perdas, tais como retrabalho e trabalho em progresso. Falhas na análise de restrições realizadas no planejamento de médio prazo têm sido apontadas como a principal razão para o surgimento de perdas por making-do, pois na ausência dos requisitos necessários para execução das atividades normalmente as equipes realizam improvisações, que podem afetar o desempenho da produção. O presente trabalho propõe um método de controle integrado produção e qualidade que permita mensurar perdas por making-do e também a ocorrência de pacotes de trabalho informais. Este método está dividido em três módulos: (a) identificação de perdas por making-do; (b) identificação de pacotes informais; e (c) controle integrado produção e qualidade. O desenvolvimento da pesquisa foi dividido nas seguintes etapas: (a) compreensão do problema; (b) estruturação do método; (c) consolidação do método; (d) avaliação dos resultados e proposição do método final. Como principais contribuições do trabalho, além do próprio método proposto, o estudo propõe uma conceitualização de perdas por making-do, retrabalho e falta de terminalidade. Ainda, os resultados demonstram a existência de uma forte relação entre as perdas por making-do, a execução de pacotes informais e o aumento do trabalho em progresso. / Waste control has been pointed out as one of the key strategies for improving the performance and reducing costs of production systems. However, despite its importance, this is a topic poorly discussed in the construction management literature, especially in relation to production control systems. Some recent studies have called the attention for a type of waste that is typical of the construction sector, named making-do, which can be defined as a loss in performance due to the execution of activities in sub-optimal conditions. It has been suggested that this type of waste is one of the root causes of quality failures, and also of other types of waste, such as rework and work in progress. Failures in constraint analysis at the medium term planning level have been pointed out a major cause of makingdo waste, as the crews tend to improvise when faced with the lack of prerequisites for the execution of tasks, which may affect the production performance. This research work proposes a method for integrated production and quality control, which enables the measurement making-do waste and also the occurrence of informal work packages This method is divided into three modules: (a) identification of making-do waste; (b) identification of informal work packages; and (c) integrated and production and quality control. The development of this research work was divided into the following stages: (a) understanding the problem; (b) structuring the method; (c) consolidating the method; (d) evaluation of results and proposition of the final version of the method. As main contributions, besides the integrated control method, this investigation proposes a conceptualization for three categories of waste: making-do, rework, and unfinished work. Moreover, the results indicate that there is a strong relationship making-do waste, the execution of informal packages and the increase of work in progress.

O controle de perdas tem sido apontado como uma das principais estratégias para melhoria do desempenho e para redução de custos de sistemas de produção. Entretanto, apesar de sua importância, este é um tema pouco abordado na literatura sobre gestão da construção, principalmente no que se refere a sistemas de controle da produção. Alguns estudos recentes chamaram a atenção para a existência de uma perda típica do setor, denominada de making-do, a qual pode ser definida como a redução de desempenho do sistema produtivo devido à execução de atividades em condições subótimas. Este tipo de perda ainda tem sido apontada como uma das causas fundamentais de problemas da qualidade, e de outras perdas, tais como retrabalho e trabalho em progresso. Falhas na análise de restrições realizadas no planejamento de médio prazo têm sido apontadas como a principal razão para o surgimento de perdas por making-do, pois na ausência dos requisitos necessários para execução das atividades normalmente as equipes realizam improvisações, que podem afetar o desempenho da produção. O presente trabalho propõe um método de controle integrado produção e qualidade que permita mensurar perdas por making-do e também a ocorrência de pacotes de trabalho informais. Este método está dividido em três módulos: (a) identificação de perdas por making-do; (b) identificação de pacotes informais; e (c) controle integrado produção e qualidade. O desenvolvimento da pesquisa foi dividido nas seguintes etapas: (a) compreensão do problema; (b) estruturação do método; (c) consolidação do método; (d) avaliação dos resultados e proposição do método final. Como principais contribuições do trabalho, além do próprio método proposto, o estudo propõe uma conceitualização de perdas por making-do, retrabalho e falta de terminalidade. Ainda, os resultados demonstram a existência de uma forte relação entre as perdas por making-do, a execução de pacotes informais e o aumento do trabalho em progresso. / Waste control has been pointed out as one of the key strategies for improving the performance and reducing costs of production systems. However, despite its importance, this is a topic poorly discussed in the construction management literature, especially in relation to production control systems. Some recent studies have called the attention for a type of waste that is typical of the construction sector, named making-do, which can be defined as a loss in performance due to the execution of activities in sub-optimal conditions. It has been suggested that this type of waste is one of the root causes of quality failures, and also of other types of waste, such as rework and work in progress. Failures in constraint analysis at the medium term planning level have been pointed out a major cause of makingdo waste, as the crews tend to improvise when faced with the lack of prerequisites for the execution of tasks, which may affect the production performance. This research work proposes a method for integrated production and quality control, which enables the measurement making-do waste and also the occurrence of informal work packages This method is divided into three modules: (a) identification of making-do waste; (b) identification of informal work packages; and (c) integrated and production and quality control. The development of this research work was divided into the following stages: (a) understanding the problem; (b) structuring the method; (c) consolidating the method; (d) evaluation of results and proposition of the final version of the method. As main contributions, besides the integrated control method, this investigation proposes a conceptualization for three categories of waste: making-do, rework, and unfinished work. Moreover, the results indicate that there is a strong relationship making-do waste, the execution of informal packages and the increase of work in progress.

Esta avaliação buscou validar a técnica de retrabalho utilizada no processo de fabricação de evaporadores automotivos, onde a falha na operação de brasagem e tratamento térmico é um dos principais motivos para o alto índice de sucata. A técnica de retrabalho consiste em refazer a operação de brasagem e tratamento térmico nos evaporadores que apresentaram falhas no teste de estanqueidade. Os evaporadores foram submetidos ao processo de rebrasagem em forno de brasagem NOCOLOK e o tratamento superficial em forno de tratamento térmico e avaliados por meio de teste de estanqueidade, utilizando-se gás Hélio (He) à pressão de 16bar e ensaio metalográfico comparativo entre peças produzidas com o ciclo normal de brasagem e tratamento térmico e com o ciclo de rebrasagem, avaliando as modificações nas juntas brasadas. Os resultados obtidos nos 05 experimentos demonstraram que houve modificações significativas nas juntas brasadas após os evaporadores terem sidos submetidos ao processo normal de brasagem, seguido de mais 04 ciclos de rebrasagem e tratamento térmico. Portanto, para a fabricação dos evaporadores automotivos fica recomendado a execução de brasagem e no máximo uma rebrasagem, eliminando a possibilidade de execução de novas rebrasagens. / This evaluation sought the validation of the rework technique used in automotive evaporators manufacturing, where this failure on brazing operation is a main reason to high level of scrap. The rework technique consists in redoing the brazing operation and thermal treatment on evaporators which fail the leak test. The evaporators were subjected to rebrazing process in NOCOLOK furnace and surface treatment in thermal treatment furnace and evaluated through leak test device, using Helium (He) at 16bar of pressure and metallographic test to compare normally produced parts with rebrazing ones, evaluating the structural changes of the material. The results got from 05 experiments made showed that there were significant changes in the brazing joint, after the evaporators being subjected to the normal brazing process, followed by 04 more rebrazing cycles and thermal treatment. Therefore, for the automotive evaporators manufacturing the brazing execution is recommended and at the most a rebrazing, eliminating the possibility of execution of new rebrazing.

A soldagem tem grande importância no setor metroferroviário, pois é empregada na fabricação de componentes estruturais e no acabamento de vagões de passageiros, que em sua maior parte são de aço inoxidável. As juntas soldadas podem apresentar descontinuidades que são interrupções que afetam as propriedades mecânicas e metalúrgicas da junta soldada. A presença destas descontinuidades, dependendo do seu tamanho, natureza ou efeito combinado, pode ocasionar a reprovação da junta soldada, quer pela redução de propriedades mecânicas ou pela não aceitação, segundo critérios estabelecidos em normas. Uma estrutura que tenha uma solda reprovada durante sua qualificação ou inspeção, pela presença de descontinuidades pode ser recuperada, por meio de um retrabalho a ser realizado nesta junta. A refusão do cordão de solda por meio do processo TIG (Tungsten Inert Gas), sem a utilização do material de adição, é uma técnica de retrabalho que pode ser empregada, em especial pela viabilidade técnica e econômica do processo. Neste estudo analisou-se a influência que o processo de reparo por soldagem TIG exerceu no comportamento mecânico e microestrutural das juntas soldadas pelo processo MIG, por meio de: ensaios mecânicos (tração, fadiga e microdureza Vickers), ensaios não destrutivos (inspeção visual e líquidos penetrantes) e caracterização microestrutural do cordão de solda. Resultados das amostras de ensaio de tração e fadiga indicaram que o reparo dos cordões de solda não alterou o comportamento mecânico das juntas. As juntas submetidas ao reparo nas quais foram retirados os reforços dos cordões apresentaram modificações nas propriedades mecânicas, mas também apresentaram resultados satisfatórios. / The welding has great importance in manufacture of subway cars because it is used in the manufacture of structural components and finishing in passenger cars which are mostly stainless steel. Joints may show the presence of discontinuities. The discontinuities are interruptions that affect the mechanical and metallurgical properties of the weld. The presence of these discontinuities, depending on their size, nature or the combined effect may lead to failure of the weld either by reduction of mechanical properties or non-acceptance criteria established in standards. A structure that has a weld failed during its qualification or inspection by the presence of discontinuities can be retrieved through a rework to be done in this joint. The remelting of the weld using the TIG process without the use of additional material, rework is a technique that can be employed in particular the technical and economic feasibility of the process. This study analyzes the influence that the process of TIG welding rework has on mechanical behavior and microstructure of welded joints by means of: mechanical tests (tensile and Vickers hardness), non-destructive testing (visual inspection and liquid penetrant) and characterization microstructure of the weld. Results of tensile test specimens and fatigue indicated that the repair of the weld beads did not change the mechanical behavior of joints. The joints subjected to repair in which they were removed the ribs of the beads showed changes in the mechanical properties, but also had satisfactory results.

La presente investigación tiene un enfoque cuantitativo que resuelve el problema de la productividad en la fabricación de estructuras metálicas que influye en los costos de la empresa Servicios Metálicos Especializados S.A.C., y para resolver este problema se trazó mejorar la productividad en la fabricación de estructuras metálicas para minimizar los costos de la empresa, aplicando la herramienta del Lookahead, que es de la metodología del Last Planner System que viene de la filosofía Lean Construction. Obteniendo una mejor planificación en el proyecto “Nuevo Almacén – Unitrade S.A.C.”, logrando un ahorro del 11.97% en los costos directos de mano de obra de fabricación de estructuras metálicas de la etapa casco, ya que se logró reducir el tiempo en un 40% comparado con el cronograma elaborado por la empresa, lo que nos dio un ahorro del 6.00% del costo directo total del proyecto. This research is a quantitative approach that solves the problem of productivity in the manufacture of metal structures influencing costs Servicios Metálicos Especializados S.A.C., and to solve this problem was traced improve productivity in manufacturing steel structures for minimize the costs of the company, Lookahead applying tool, which is the methodology of the Last Planner System next Lean Construction philosophy. It getting better planning in the “Nuevo Almacén – Unitrade S.A.C.” project, achieving a saving of 11.97% on the direct costs of labor manufacturing metal structures of town stage, since it is possible to reduce time by 40% compared with the schedule prepared by the company, which gave a saving of 6.00% of the total direct cost of the project.

Stamping dies are used in the Sheet Metal Forming (SMF) process for manufacturing of car body parts. The lead time for design and manufacturing of a stamping die is long, and therefore costly. In the final step of the manufacturing process, manual rework is performed to reach a desired pressure distribution on the forming surfaces in order to achieve a robust process and an approved part within tolerance. The main purpose for this work is to study and further develop a Virtual Rework Method that alters the shape of the forming surfaces of a die to compensate for the displacements of a stamping press that occur during stamping. Measurements were performed to obtain the displacements that occur in the stamping press during stamping. These measurements were performed on a double action deep drawing press of the brand Danly, located at Volvo Cars Tool & Die department in Olofström, Sweden. The measurement yields information of how the stamping press is deflecting and deforming during operation. The measurements are recorded with a Digital Image Correlation (DIC) system that records the displacements of the press during stamping. The displacements obtained in the measurements are then used as constraints to inverse FE- model a press table with topology optimization. This optimized press table is used in the Virtual Rework Method to be able to simulate both the deformations of the press and the internal deformations that occur in the die. Pre-simulations were performed before the measurements to ensure that the blank holder plate used in the measurements would withstand the applied blank holder force. These simulations also yield if the displacements were large enough for the ARAMIS DIC system to capture. The FE-model used in this work consisted of a die, blank holder, blank holder plate, outer ram and the optimized press table. The Virtual Rework Method was applied on the FE-model, where the result concludes that the altered shape of the deformed forming surfaces is almost identical to the shape of the nominal forming surfaces. However, an inversed modelled structure that represents the behavior of the outer ram is required to apply the Virtual Rework Method on the blank holder. This inversed modelled structure could be created from the displacements obtained in the measurements. To apply the Virtual Rework method on the punch, further measurements are required, where the position of the ARAMIS DIC system is altered, or an additional ARAMIS DIC system is used. / Pressverktyg används i plåtformningsprocessen vid tillverkning av karossdelar. Ledtiden för konstruktion och tillverkning av ett pressverktyg är lång och därför kostsam. I det sista steget i tillverkningsprocessen utförs manuell bearbetning för att nå en önskad tryckfördelning på formningsytorna, vilket ger en robust process och en godkänd del inom toleranserna. Huvudsyftet med detta arbetet är att studera och vidareutveckla en virtuell fläckningsmetod som korrigerar formningsytorna på dynan för att kompensera för de förskjutningar som uppstår i en stämplingspress under stämpling. Mätningar har utfördes för att erhålla förskjutning som uppstår i en stämplingspress under stämpling. Dessa mätningar utfördes på en dubbelverkande djupdragningspress av märket Danly, som finns hos Volvo Cars Tool & Die avdelning i Olofström, Sverige. Mätningen gav information om hur pressen deformeras under stämpling. Mätningarna registreras med ett Digital Image Correlation (DIC) system som registrerar pressens förskjutningar under stämpling. Förskjutningarna som erhållits i mätningarna användes sedan som randvillkor för en inversmodell för topologioptimering av ett pressbord. Detta optimerade pressbord används sedan i den Virtuella fläckningsmetoden för att kunna simulera både pressens stelkroppsrörelse och de interna deformationer som uppstår i pressverktyget. En förstudie utfördes innan mätningarna för att säkerställa att den plåthållarplattan som användes i mätningarna skulle motstå den applicerade plåthållarkraften. Denna förstudie gjordes även för att säkerhetsställa att förskjutningarna som uppstår i plåthållarplattan var stora nog för att ARAMIS DIC systemet skulle registrera dem. FE-modellerna som användes i detta arbete bestod av en dyna, plåthållare, plåthållarplatta, yttre slid och det optimerade pressbordet. Den Virtuella fläckningsmetoden applicerades på FE- modellen, där resultatet gav slutsatsen att den korrigerade formningsytan med applicerad belastning är nästintill identisk med formen på den nominella formningsytan. En inversmodellerad struktur som representerar beteendet hos den yttre sliden krävs emellertid för att tillämpa den Virtuella fläckningsmetoden på plåthållaren. Denna inversmodellerade struktur kunde erhållas från de förskjutning som erhölls i mätningarna. För att tillämpa den Virtuella fläckningsmetoden på stansen krävs ytterligare mätningar, där ARAMIS DIC systemets position ändras eller ett ytterligare ARAMIS DIC system används. / Reduced Lead Time through Advanced Die Structure Analysis - Vinnova

In this paper, we will show that the economic lot-sizing problem with rework of defectives is NP-hard. Therefore, we reduce it to the well-known PARTITION problem. This is in line with the findings for similar models that in-vestigate lot-sizing with remanufacturing.

In manufacturing systems subject to machine and operator resource constraints the effects of rework can be profound. High levels of rework burden the resources unnecessarily and as the utilization of these resources increases the expected queuing time of work in process increases exponentially. Queuing models can help managers to understand and control the effects of rework, but often this tool is overlooked in part because of concerns over accuracy in complex environments and/or the need for limiting assumptions. One aim of this work is to increase understanding of system variables on the accuracy of simple queuing models. A queuing model is proposed that combines G/G/1 modeling techniques for rework with effective processing time techniques for machine availability and the accuracy of this model is tested under varying levels of rework, external arrival variability, and machine availability. Results show that the model performs best under exponential arrival patterns and can perform well even under high rework conditions. Generalizations are made with regards to the use of this tool for allocation of jobs to specific workers and/or machines based on known rework rates with the ultimate aim of queue time minimization.