28,500 research outputs found

    Balancing Workload and Workforce Capacity in Lean Management: Application to Multi-Model Assembly Lines

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    While multi-model assembly lines are used by advanced lean companies because of their flexibility (different models of a product are produced in small lots and reach the customers in a short lead time), most of the extant literature on how to staff assembly lines focuses either on single-model lines or on mixed-model lines. The literature on multi-model lines is scarce and results given by current methods may be of limited applicability. In consequence, we develop a procedure to staff multi-model assembly lines while taking into account the principles of lean manufacturing. As a first approach, we replace the concepts of operation time and desired cycle time by their reciprocal magnitudes workload and capacity, and we define the dimensionless term of unit workload (load/capacity ratio) in order to avoid magnitudes related to time such as cycle time because, in practice, they might not be known. Next, we develop the necessary equations to apply this framework to a multi-model line. Finally, a piece of software in Python is developed, taking advantage of Google’s OR-Tools solver, to achieve an optimal multi-model line with a constant workforce and with each workstation performing the same tasks across all models. Several instances are tested to ensure the performance of this method

    "The Shift from Belt Conveyor Line to Work-cell Based Assembly Systems to Cope with Increasing Demand Variation and Fluctuation in The Japanese Electronics Industries"

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    As consumption patterns become increasingly sophisticated and manufacturers strive to improve their competitiveness, not only offering higher quality at competitive costs, but also by providing broader mix of products, and keeping it attractive by launching successively new products, the turbulence in the markets has intensified. This has impelled leading manufacturers to search the development of alternative production systems supposed to enable them operate more responsively. This paper discusses the trend of abandoning the strategy of relying on factory automation technologies and conveyor-based assembly lines, and shifting towards more human-centered production systems based on autonomous work-cells, observed in some industries in Japan (e.g. consumer electronics, computers, printers) since mid-1990s. The purpose of this study is to investigate this trend which is seemingly uneconomic to manufacturers established in a country where labor costs are among the highest in the world, so as to contribute in the elucidation of its background and rationality. This work starts with a theoretical review linking the need to cope with nowadays' market turbulence with the issue of nurturing more agile organizations. Then, a general view of the diffusion trend of work-cell based assembly systems in Japanese electronics industries is presented, and some empirical facts gathered in field studies conducted in Japan are discussed. It is worthy mentioning that the abandonment of short cycle-time tasks performed along conveyor lines and the organization of workforce around work-cells do not imply a rejection of the lean production paradigm and its distinctive process improvement approach. High man-hour productivity is realized as a key goal to justify the implementation of work-cells usually devised to run in longer cycle-time, and the moves towards this direction has been strikingly influenced by the kaizen philosophy and techniques that underline typical initiatives of lean production system implementation. Finally, it speculates that even though the subject trend is finding wide diffusion in the considered industries, it should not be regarded as a panacea. In industries such as manufacturing of autoparts, despite the notable product diversification observed in the automobile market, its circumstances have still allowed the firms to rely on capital-intensive process, and this has sustained the development of advanced manufacturing technologies that enable the agile implementation and re-configuration of highly automated assembly lines.

    Lean manual assembly 4.0: A systematic review

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    In a demand context of mass customization, shifting towards the mass personalization of products, assembly operations face the trade-off between highly productive automated systems and flexible manual operators. Novel digital technologies—conceptualized as Industry 4.0—suggest the possibility of simultaneously achieving superior productivity and flexibility. This article aims to address how Industry 4.0 technologies could improve the productivity, flexibility and quality of assembly operations. A systematic literature review was carried out, including 234 peer-reviewed articles from 2010–2020. As a result, the analysis was structured addressing four sets of research questions regarding (1) assembly for mass customization; (2) Industry 4.0 and performance evaluation; (3) Lean production as a starting point for smart factories, and (4) the implications of Industry 4.0 for people in assembly operations. It was found that mass customization brings great complexity that needs to be addressed at different levels from a holistic point of view; that Industry 4.0 offers powerful tools to achieve superior productivity and flexibility in assembly; that Lean is a great starting point for implementing such changes; and that people need to be considered central to Assembly 4.0. Developing methodologies for implementing Industry 4.0 to achieve specific business goals remains an open research topic

    The Role of Management Practices in Closing the Productivity Gap

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    There is no doubt that management practices are linked to the productivity and performance of a company. However, research findings are mixed. This paper provides a multi-disciplinary review of the current evidence of such a relationship and offers suggestions for further exploration. We provide an extensive review of the literature in terms of research findings from studies that have been trying to measure and understand the impact that individual management practices and clusters of management practices have on productivity at different levels of analysis. We focus our review on Operations Management (om) and Human Resource Management (hrm) practices as well as joint applications of these practices. In conclusion, we can say that taken as a whole, the research findings are equivocal. Some studies have found a positive relationship between the adoption of management practices and productivity, some negative and some no association whatsoever. We believe that the lack of universal consensus on the effect of the adoption of complementary management practices might be driven either by measurement issues or by the level of analysis. Consequently, there is a need for further research. In particular, for a multi-level approach from the lowest possible level of aggregation up to the firm-level of analysis in order to assess the impact of management practices upon the productivity of firms

    On the Interface Between Operations and Human Resources Management

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    Operations management (OM) and human resources management (HRM) have historically been very separate fields. In practice, operations managers and human resource managers interact primarily on administrative issues regarding payroll and other matters. In academia, the two subjects are studied by separate communities of scholars publishing in disjoint sets of journals, drawing on mostly separate disciplinary foundations. Yet, operations and human resources are intimately related at a fundamental level. Operations are the context that often explains or moderates the effects of human resource activities such as pay, training, communications and staffing. Human responses to operations management systems often explain variations or anomalies that would otherwise be treated as randomness or error variance in traditional operations research models. In this paper, we probe the interface between operations and human resources by examining how human considerations affect classical OM results and how operational considerations affect classical HRM results. We then propose a unifying framework for identifying new research opportunities at the intersection of the two fields

    Productivity and flexibility improvement of assembly lines for high-mix low-volume production. A white goods industry case

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    Las tendencias globales de la personalización e individualización en masa impulsan la producción industrial en serie corta y variada; y por tanto una gran variedad de productos en pequeñas cantidades. Por ello, la customización en masa precisa de sistemas de ensamblaje que sean a la vez altamente productivos y flexibles, a diferencia de la tradicional oposición entre ambas características. La llamada cuarta revolución industrial trae diversas tecnologías habilitadoras que podrían ser útiles para abordar este problema. Sin embargo, las metodologías para implementar el ensamblaje 4.0 todavía no han sido resueltas. De hecho, para aprovechar todas las ventajas potenciales de la Industria 4.0, es necesario contar con un nivel previo de excelencia operacional y un análisis holístico de los sistemas productivos. Esta tesis tiene como objetivo entender y definir cómo mejorar la productividad y la flexibilidad de las operaciones de montaje en serie corta y variada.Esta meta se ha dividido en tres objetivos. El primer objetivo consiste en comprender las relaciones entre la Industria 4.0 y las operaciones de ensamblaje, así como sus implicaciones para los operarios. El segundo objetivo consiste en desarrollar una metodología y las herramientas necesarias para evaluar el rendimiento de diferentes configuraciones de cadenas de ensamblaje. El último objetivo consiste en el diseño de sistemas de ensamblaje que permitan incrementar su productividad al menos un 25 %, produciendo en serie corta y variada, mediante la combinación de puestos de montaje manual y estaciones automatizadas.Para abordar la fase de comprensión y definición del problema, se llevó a cabo una revisión bibliográfica sistemática y se desarrolló un marco conceptual para el Ensamblaje 4.0. Se desarrollaron, verificaron y validaron dos herramientas de evaluación del rendimiento: un modelo matemático analítico y varios modelos de simulación por eventos discretos. Para la verificación, y como punto de partida para los análisis, se ha utilizado un caso de estudio industrial de un fabricante global de electrodomésticos. Se han empleado múltiples escenarios de simulación y técnicas de diseño de experimentos para investigar tres cuestiones clave.En primer lugar, se identificaron los factores más críticos para el rendimiento de líneas de montaje manuales multi-modelo. En segundo lugar, se analizó el rendimiento de líneas de montaje semiautomáticas paralelas con operarios móviles en comparación con líneas semiautomáticas o manuales con operarios fijos, empleando diversos escenarios de demanda en serie corta y variada. Por último, se investigó el uso de trenes milkrun para la logística interna de líneas de ensamblaje multi-modelo bajo la influencia de perturbaciones.Los resultados de las simulaciones muestran que las líneas paralelas con operarios móviles pueden superar a las de operarios fijos en cualquier escenario de demanda, alcanzando como mínimo el objetivo de mejorar la productividad en un 25% o más. También permiten reducir cómodamente el número de operarios trabajando en la línea sin afectar negativamente al equilibrado de la misma, posibilitando la producción eficiente de bajo volumen. Los resultados de las simulaciones de logística interna indican que los milkrun pueden proteger las líneas de ensamblaje de las perturbaciones originadas en procesos aguas arriba.Futuras líneas de investigación en base a los resultados obtenidos en esta tesis podrían incluir la expansión e integración de los modelos de simulación actuales para analizar las cadenas de montaje paralelas con operarios móviles incorporando logística, averías y mantenimiento, problemas de control de calidad y políticas de gestión de los retrabajos. Otra línea podría ser el uso de diferentes herramienta para el análisis del desempeño como, por ejemplo, técnicas de programación de la producción que permitan evaluar el desempeño operacional de diferentes configuraciones de cadenas de montaje con operarios móviles, tanto en términos de automatización como de organización en planta. Podrían incorporarse tecnologías de la Industria 4.0 a los modelos de simulación para evaluar su impacto operacional global ¿como cobots para ensamblaje o para la manipulación de materiales, realidad aumentada para el apoyo cognitivo a los operarios, o AGVs para la conducciónde los trenes milkrun. Por último, el trabajo presentado en esta tesis acerca las líneas de ensamblaje semiautomáticas con operarios móviles a su implementación industrial.<br /

    Interpretive Structural Modelling for Challenging Issues in JIT Supply Chain: Product Variety Perceptive

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    The success of JIT in Japan inspired many organizations to adopt JIT to the supply chain in order to reduce the waste and cost. These organizations have to face inherent challenging issues and complexities while implementing JIT concepts in supply chain. The manufacturer must be in position to identify challenging issues, its consequences so as to design a robust and reliable supply chain accordingly otherwise the manufacturing system may not provide the desired results. The focus of this paper is on the significant challenging issues in JIT supply chain from product variety perspective. Some challenging issues act as driver for sustainable implementation of JIT supply chain. For adoption of JIT supply chain, significant issues must be identified, analysed and discussed. In this research, study factors are the challenging issues for sustainable JIT supply chain implementation. Authors have identified ten significant issues from literature review. The main objectives are to identify and rank the challenging issues for implementation, to develop and to analysed the interaction between identified challenging issues using ISM and to prepare a framework for successful JIT supply chain implementation

    Lean assessment tool for workstation design of assembly lines

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    Efficiently designed workstations are essential to provide both flexibility and mass production in an effective way. Unfortunately, it is common to find industrial workstations built without a purposeful design. The design of the workstation, oriented to both users and tasks requirements, allows organisations to increase their production indicators (less time, space and cost) and quality levels. Within the present paper, an assessment tool was developed to address a literature gap regarding the lack of tools to evaluate Workstation Design, particularly in assembly lines. The concept of “Hierarchy of Workstation needs” is introduced for prioritising the requirements to achieve full performance in workstations. The concept is visualised as a pyramid split in four levels to achieve excellence: functionality, effectiveness, efficiency and satisfaction. Seven requirements were identified for Workstation Design, namely: “Health and Safety”, “Work environment, cleanliness and orderliness”, “Waste elimination”, “Inventory and material logistics”, “Flexibility”, “Visual Management” and, lastly, “Quality”. An evaluation model and a tool to assess each requirement was developed based on lean and ergonomic aspects and specific for workstation design, which it is difficult to found in other assessment tools. This model has the form of a checklist that is based on the current best practices in Workstation Design of assembly lines. The assessment tool was validated in an automotive assembly line and based on the results obtained, improvements in the associate working zones, workstation dimensions, storage areas or parts feeding system are introduced to improve “Waste elimination” and “Inventory and material logistics”. Paper presented at: Complex Systems Engineering and Development Proceedings of the 27th CIRP Design Conference Cranfield University, UK 10th – 12th May 2017

    Improving supply chain management in construction: what can be learned from the aerospace industry?

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    In order to provide for controllable delivery, reliable lead times and efficient customer response, lean manufacturing and platform assembly practices play an important role in supply chains in the aerospace industry. The adoption of lean manufacturing practices ensures an efficient delivery of products to the market. Benefits from the development of platform strategies are a more reliable materials supply and an improved logistics control. The aerospace industry is characterized by a small number of major global players and many small ones. A major part of the design and production has been contracted out to suppliers. In this paper the basic similarities and differences between the construction and aerospace industry and supply chains are analysed. A comparative study of aerospace and construction supply chains is presented to indicate and discuss the applicability of supply chain management concepts to construction, and the improvement potential of these concepts regarding supply chain management in construction. It is concluded that in particular the practice of platform assembly is a fruitful concept to be applied in the construction industry

    Questioning the relentless shift to offshore manufacturing

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    The last 20 years has seen a relentless shift to offshore manufacturing as retailers chase ever-lower labor costs. The results of this strategy can now be evaluated and we propose that some adjustments are in order. We analyze the case of a North American apparel manufacturer (Griffin Manufacturing, Inc.) that has successfully emerged from a period of major change with a strong and strategic position in the apparel supply chain. This case study documents Griffin’s survival through evolution in capabilities, technology, and especially attitude. The Griffin case study suggests that keeping a portion of the manufacturing onshore at an agile, quick response factory is cost effective: it increases sales and improves margins. However, the new relationship between the parties is much more complex and requires commitment on both sides
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