Integration of a collaborative robot in a U-shaped production line: a real case study

In lean production environments, such as the U-shaped cells, flexibility is a priority. Therefore, any element that introduces process stiffness is negatively valued. Former studies establish that robotization of tasks in U-shaped cells presents some drawbacks. For instance: it may complicate continuous improvement, prolong changeover time, use a large space or create safety problems for the operators. However, the collaborative robots (CoBots) may change this situation, since they overcome most of the issues previously mentioned. The present study analyses a real case of de-robotization in a traditional assembly line to transform it into a manual U-shaped line. In a second step a CoBot is integrated in the cell replacing one of the workers. This study empirically compares the manufacturing process in these three scenarios. Results in real production conditions show that a U-shape cell assisted by a CoBot increases productivity and reliability while reducing the surface used. These results suggest that collaborative robotics can be integrated in U-shaped production lines and even increase the efficiency of a traditional robotized assembly line.Peer ReviewedPostprint (published version

Diseño Desde la Persona: hacia una metodología de diseño de Sistemas de Producción Lean basada en el respeto a las personas y la optimización de la superficie Person-Based-Design: towards a design methodology for Lean Production Systems based on respect-for-human and surface optimization

En las últimas décadas, el incremento de la competitividad de los mercados globales ha popularizado en término “Lean” como una forma de organización industrial capaz de conseguir altos niveles de calidad, productividad y cortos plazos de entrega, en un entorno de producción de series cortas y variadas. Hasta el punto de que su sobreuso ha generado confusión y una cierta pérdida de su sentido original.Los Sistemas de Producción Lean se basan en el Sistema de Producción Toyota, desarrollado en los años 60 del siglo XX y ampliamente difundido a partir de los años 90 como “Lean Production” tras las conclusiones del International Motor Vehicule Program (IMVP) conducido por el Massachusetts Institute of Technology (MIT) desde 1979.Uno de los pilares fundacionales del Sistema de Producción Lean es el respeto por las personas (respect-for-human). Sin embargo, la literatura muestra una falta de interés sobre este concepto, a la vez que una progresiva pérdida de visión holística en favor de las herramientas.En este sentido, el análisis de la bibliografía sobre la aplicación de dichas herramientas muestra una paradoja difícil de conciliar: ¿cómo se puede implicar a las personas en la mejora de la eficiencia del sistema si ello puede acarrear su despido?El objeto de esta tesis es proponer una metodología de diseño para un Sistema de Producción Lean que ayude a mitigar esta paradoja y se apoye, como indicador de mejora, en la productividad de la superficie en lugar de la tradicional productividad humana.Para ello propone el método Person-Based Design (Diseño desde la Persona) en siete capas concéntricas con una única regla de diseño: mejorar la eficiencia de cada capa sin que ello perjudique la eficiencia de las capas que contiene.Después desarrolla metodologías concretas de diseño y optimización de las 5 capas más internas con la reducción del espacio industrial ocupado como hilo conductor. En particular, modeliza una topología de Células en U orientada a la gestión óptima del espacio ocupado; después propone un método de diseño de su sistema de aprovisionamiento (milk-run) para minimizar la superficie y el esfuerzo del conductor; finalmente muestra cómo la introducción de tecnologías de la Industria 4.0 puede contribuir a compactar células de producción eliminado trabajos penosos para las personas a través del uso de robots colaborativos (Cobots).<br /

A geometrical model for managing surface productivity of U-Shaped assembly lines

U-Shaped Assembly Lines (U-SALs) are cellular manufacturing systems that, among other things, provide a remarkable feature for industrial cost efficiency: their effectiveness in space utilization. While the challenge of machine placement for labour productivity optimization is widely studied in the literature, surface productivity optimization has been scarcely explored. This paper proposes an industry-validated geometrical model for optimizing U-SAL surface productivity. The model links the drivers for market, product and process with the geometrical design. Managers and lean practitioners can use this approach to make decisions for layout design. The model is particularly useful in cases where the cost of floor space is substantially high.Peer ReviewedPostprint (author's final draft

An in-plant milk-run design method for improving surface occupation and optimizing mizusumashi work time

Product customization is becoming a competitiveness factor in most markets. It implies manufacturing small and varied batches in mixed-product assembly lines and frequently supplying parts to production lines in small quantities with high efficiency. The in-plant milk-run is a specific tool used in this context. This paper proposes an industry-validated design method for human-driven milk-runs, based on improving surface productivity. A mathematical model is defined for relating mizusumashi work time to the milk-run period and finding its minimum value. This research is particularly useful in factories with high cost per m2 supplying high-volume parts.Peer ReviewedPostprint (author's final draft

Person-Based Design: a human-centered approach for lean factory design

In a highly competitive and changing industrial environment, an organizational system that remains permanently aligned with the market is becoming a competitiveness factor. The literature shows that the empowerment of people is a key factor for maintaining and improving such a system. Consequently, industrial organizations face the challenge of building effective production systems that integrate the development of people, thus improving their capacities and skills for solving complex problems while respecting their needs and aspirations as individuals. This challenge is particularly relevant when intensive handwork is needed and, consequently, high pressure on labor (and space) productivity constitutes the main cost drivers. This paper proposes a method to design lean factories, thus fostering high productivity rates and respect-for-human. We develop here a holistic model for a system as an integrated set of Principles, Tools and Methods in constant interaction with people. Afterwards, the model is specified for Lean Production Systems. We propose a specific human-centered method (Person-Based Design) to guide an effective lean factory design in a real industrial setting, and then we present some results from its implementation. The outcomes of this research provide a coherent mindset for managers facing an organizational change, and our structured method allows for the design of effective lean factories, which are particularly useful when space and/or labor productivity constitute the main factors of a firm’s competitivenessPeer Reviewe

Multi-Model In-Plant Logistics Using Milkruns for Flexible Assembly Systems under Disturbances: An Industry Study Case

Mass customisation demand requires increasingly flexible assembly operations. For the in-plant logistics of such systems, milkrun trains could present advantages under high variability conditions. This article uses an industrial study case from a global white-goods manufacturing company. A discrete events simulation model was developed to explore the performance of multi-model assembly lines using a set of operational and logistics Key Performance Indicators. Four simulation scenarios analyse the separate effects of an increased number of product models and three different sources of variability. The results show that milkruns can protect the assembly lines from upstream process disturbances

Integration of a collaborative robot in a U-shaped production line: a real case study

In lean production environments, such as the U-shaped cells, flexibility is a priority. Therefore, any element that introduces process stiffness is negatively valued. Former studies establish that robotization of tasks in U-shaped cells presents some drawbacks. For instance: it may complicate continuous improvement, prolong changeover time, use a large space or create safety problems for the operators. However, the collaborative robots (CoBots) may change this situation, since they overcome most of the issues previously mentioned. The present study analyses a real case of de-robotization in a traditional assembly line to transform it into a manual U-shaped line. In a second step a CoBot is integrated in the cell replacing one of the workers. This study empirically compares the manufacturing process in these three scenarios. Results in real production conditions show that a U-shape cell assisted by a CoBot increases productivity and reliability while reducing the surface used. These results suggest that collaborative robotics can be integrated in U-shaped production lines and even increase the efficiency of a traditional robotized assembly line.Peer Reviewe

A geometrical model for managing surface productivity of U-Shaped assembly lines

U-Shaped Assembly Lines (U-SALs) are cellular manufacturing systems that, among other things, provide a remarkable feature for industrial cost efficiency: their effectiveness in space utilization. While the challenge of machine placement for labour productivity optimization is widely studied in the literature, surface productivity optimization has been scarcely explored. This paper proposes an industry-validated geometrical model for optimizing U-SAL surface productivity. The model links the drivers for market, product and process with the geometrical design. Managers and lean practitioners can use this approach to make decisions for layout design. The model is particularly useful in cases where the cost of floor space is substantially high.Peer Reviewe

Casos de ingeniería de organización

Esta obra presenta una colección de 18 casos que han sido creados como resultado del proyecto de innovación docente “Transversalidad en el diseño curricular del Máster Universitario en Ingeniería de Organización”. El proyecto de innovación docente contó con el apoyo del Instituto de Ciencias de la Educación de la Universitat Politècnica de Catalunya y tuvo como finalidad aumentar la interconexión de los contenidos impartidos en el citado Máster. La colección de casos incluidos en esta obra se utiliza como material docente transversal. Hemos indicado en cada caso las asignaturas para las que fueron creados. Para información complementaria sobre las propuestas de resolución de los casos o sus notas de enseñanza, encontrará los datos de contacto de los autores al final del libro