Incorporating working conditions to a mixed- model sequencing problem

Partiendo de una variante de un problema de secuenciación en líneas de productos mixtos (MMSP-W: Mixed-Model Sequencing Problem with Workload Minimisation), se proponen dos nuevos modelos que incorporan condiciones laborales a los puestos de trabajo de la línea. El primero tiene en cuenta la limitación de la saturación de los puestos de trabajo, mientras que el segundo contempla, además, la activación de los operarios a lo largo de la jornada laboral. Se realizan sendas experiencias computacionales, empleando un caso de estudio de la planta de motores de Nissan en Barcelona, con dos propósitos: (1) estudiar la repercusión que ocasiona la limitación de la saturación sobre la caída de la productividad de la línea, y (2) evaluar la recuperación de la productividad de la línea, mediante la activación de los operarios, manteniendo la misma calidad en las condiciones laborales conseguida al limitar la saturación.Beginning with a variation of the sequencing problem in a mixed-products line (MMSP-W: Mixed-Model Sequencing Problem with Workload Minimization), we propose two new models that incorporate the working conditions into the workstations on the line. The first model takes into account the saturation limit of the workstations, and the second model also includes the activation of the operators throughout the working day. Two computational experiments were carried out using a case study of the Nissan motor plant in Barcelona with two main objectives: (1) to study the repercussions of the saturation limit on the decrease in productivity on the line and (2) to evaluate the recovery of productivity on the line via activation of operators while maintaining the same quality in working conditions achieved by limiting the saturation. The obtained results show that the saturation limitation leads to suppose an important increase of work overload, which means average economic losses of 28,731.8 euros/day. However, the consideration of activity reduces these losses by 62.7%.Preprin

Delimiting the linear area on the problems of assembly line balancing with minimal ergonomic risk

In this paper we propose to incorporate some working conditions to the assembly lines. For this, used a mathematical model to solve the assembly line balancing problem whose objective is minimizing the ergonomic risk, imposing the limitation of the cycle time, number of workstations and the maximum linear area for each station. A study is presented through a case study that corresponds to an assembly line from Nissan’s plant in Barcelona.Postprint (published version

Consideration of human resources in the Mixed-model Sequencing Problem with Work Overload Minimization: Legal provisions and productivity improvement

Beginning with a variation of the sequencing problem in a mixed-products line (MMSP-W: Mixed-Model Sequencing Problem with Workload Minimization), we propose two new models that incorporate a set of working conditions in regard with human resources of workstations on the line. These conditions come from collective agreements and therefore must be respected by both company and labor unions. The first model takes into account the saturation limit of the workstations, and the second model also includes the activation of the operators throughout the working day. Two computational experiments were carried out using a case study of the Nissan motor plant in Barcelona with two main objectives: (1) to study the repercussions of the saturation limit on the decrease in productivity on the line and (2) to evaluate the recovery of productivity on the line via both activation of operators, while maintaining the same quality in working conditions achieved by limiting the saturation, and auxiliary processors. By results we state that saturation limitation leads an important increase of work overload, which means average economic losses of 28,731.8 Euros/day. However, the productivity reduction may be counteracted by the work pace factor increase, at certain moments of workday, and/or by the incorporation of auxiliary processors into the line.Postprint (author's final draft

Ergonomía y evaluación del riesgo ergonómico

Descripción básica de los métodos RULA, NIOSH y OCRA. UnificaciónHoy en día los trabajadores se ven obligados a adaptarse a muchas y muy diversas condiciones laborales que pueden afectar gravemente a su salud. Por ello, se presenta y analiza la información básica relativa a la Ergonomía haciendo hincapié en las dolencias que pueden aparecer a lo largo de la jornada laboral tanto psíquicas como físicas. A continuación, se describen los métodos ergonómicos más utilizados a lo largo de los años que permiten identificar y evaluar los riesgos ergonómicos a los que se encuentran expuestos los trabajadores, proponiendo opciones para su mejora y emplazándolos a un niveles aceptables. Como parte a destacar, se presenta una unificación de tres métodos ergonómicos (RULA, NIOSH y OCRA) para obtener un único valor de riesgo ergonómicoPreprin

Maximizing comfort in Assembly Lines with temporal, spatial and ergonomic attributes

We aim at maximizing the comfort of operators in mixed-model assembly lines. To achieve this goal, we evaluate two assembly line balancing models: the first that minimizes the maximum ergonomic risk and the second one that minimizes the average absolute deviations of ergonomic risk. Through a case study we compare the results of the two models by two different resolution procedures: the Mixed Integer Linear Programming (MILP) and Greedy Randomized Adaptive Search Procedures (GRASP). Although linear programming offers best solution, the results given by GRASPs are competitive.Peer ReviewedPostprint (author's final draft

Design and balancing of assembly lines that minimize ergonomic risk

Minimización del Riesgo ergonómico de la línea de motores de Nissan-BCN en función del número de estaciones de trabajo.In this paper, an assessment system of the ergonomic hazards existing in the workstations of an assembly line is provided. A mathematic model to solve the assembly line balancing problem is developed with the aim of minimizing the ergonomic risk that exists in an assembly line by taking into account the number of workstations and a set of temporal and spatial restrictions. This model has been applied, by means of a computational experiment, in a problem taken from a case study of Nissan’s engine plant in Barcelona. The experiment measures the impact that the increase in the number of workstations causes on the improvement of the ergonomic quality of such workplaces and on the reduction of the ergonomic risk.Preprin

Solving the mixed model sequencing problem with workload minimization with product mix preservation

This work is supported by the Spanish Ministerio de Educación y Ciencia under Project DPI2010-16759 (PROTHIUS-III) including EDRF fundings.Postprint (published version

Consideration of human resources in the Mixed-model Sequencing Problem with Work Overload Minimization: Legal provisions and productivity improvement

Postprint ESWA Volume 42, Issue 22, 1 December 2015, Pages 8896–8910Beginning with a variation of the sequencing problem in a mixed-products line (MMSP-W: Mixed-Model Sequencing Problem with Workload Minimization), we propose two new models that incorporate a set of working conditions in regard with human resources of workstations on the line. These conditions come from collective agreements and therefore must be respected by both company and labor unions. The first model takes into account the saturation limit of the workstations, and the second model also includes the activation of the operators throughout the working day. Two computational experiments were carried out using a case study of the Nissan motor plant in Barcelona with two main objectives: (1) to study the repercussions of the saturation limit on the decrease in productivity on the line and (2) to evaluate the recovery of productivity on the line via both activation of operators, while maintaining the same quality in working conditions achieved by limiting the saturation, and auxiliary processors. By results we state that saturation limitation leads an important increase of work overload, which means average economic losses of 28,731.8 Euros/day. However, the productivity reduction may be counteracted by the work pace factor increase, at certain moments of workday, and/or by the incorporation of auxiliary processors into the line.Postprint (published version

GRASP for sequencing mixed models in an assembly line with work overload, useless time and production regularity

Peer ReviewedPostprint (published version

GRASP para secuenciar modelos mixtos en una línea con sobrecarga, tiempo inerte y regularidad en la producción

Se presenta un algoritmo GRASP para resolver un problema de secuenciación de productos en una línea de montaje de modelos mixtos. El objetivo del problema es obtener una secuencia de fabricación de productos con máximo trabajo total completado y cumpliendo la propiedad de regularidad en la producción. El algoritmo GRASP implementado se compara con otros procedimientos de resolución, empleando para ello las instancias de un caso de estudio asociado a la planta de fabricación de motores de Nissan en Barcelona.Postprint (author's final draft