An expert system to minimize operational costs in mixed-model sequencing problems with activity factor

• Published in: Expert systems with applications 2018-08, Vol.104, p.185-201
• Main Authors: Bautista Valhondo, Joaquín, Alfaro Pozo, Rocío
• Format: Article
• Language: English
• Subjects: Activation; Activity factor; Assembly lines; Assembly-line methods; Business competition; Business law; Compensation costs; Cost engineering; Direcció d'operacions; Economia i organització d'empreses; Economic compensation; Economic models; Employee benefits; Environmental legislation; Expert systems; Heuristic algorithms; Heurística; Idle time; Idling; Labor; Mathematical optimization; Mixed-model assembly lines; Operators; Optimització matemàtica; Production costs; Production engineering; Productivity; Sequences; Sequencing; Stress; Treball en cadena; Work overload; Work pace; Working conditions; Àrees temàtiques de la UPC
• ISSN: 0957-4174; 1873-6793
• DOI: 10.1016/j.eswa.2018.03.031

•Minimization of operational costs by work overloads and useless time in mixed-model sequences.•Bounded activation of operators of assembly line in order to improve productivity.•Economic compensation of excess effort of operators.•Economic gains for the company and operators because of the recovery of production drop.•Computational experience linked to the Nissan's powertrain plant in Barcelona. One of the major issues in industrial environments is currently maximizing productivity while reducing manufacturing cost. This can be seen clearly reflected in mixed-model assembly lines based systems, where obtaining efficient manufacturing sequences is a key to be competitive in a dynamic and globalized market. However, this continuous cost reduction and productivity growth should not penalize the welfare of employees. This work is intended to address this lack of compatibility between the economic and social objectives through the study of the mixed-model sequencing problem from both the business and labor perspective. This is done by considering the possibility of reducing or increasing processing times of operations by varying the work pace of line's operators within the permissible legal boundaries. Thus, depending on this flexible activation time of operators, the amount of completed work and idle time will be one or the other and, consequently, the productivity of the line will also improve or get worse. In this regard, we propose new approach to the sequencing problem without incurring cost increases and providing a safe working environment, in accordance with applicable law. This new approach leads to obtain efficient manufacturing sequences, in terms of both productivity and labor conditions. Specifically, the objective of the new problem is minimizing the unproductive costs of the line by incorporating the possibility of increasing production through the variation of the work pace of line's operators. Increasing the work pace of operators, the amount of non-completed work or the preventable idle time can be reduced and therefore, their associated costs too. In addition, and without losing sight of the effort involved in working with a work pace above the normal, we propose several economic criteria to compensate the activation of workers where necessary.