Joaquín Bautista Valhondo

Solving a Mixed-Model Sequencing Problem with production mix restriction by Bounded Dynamic Programming

In this article, we propose a hybrid procedure based on bounded dynamic programming (BDP) assisted by linear programming to solve the mixed-model sequencing problem with workload minimization (MMSP-W) with serial workstations, free interruption of the operations and with production mix restrictions. We performed a computational experiment with 23 instances related to a case study of the Nissan powertrain plant located in Barcelona. The results of our proposal are compared with those obtained by the Gurobi solver and previous procedures. MSC:90C39, 90B35

A conceptual model to manage supply sequences in automotive industry for Nissan Barcelona

This paper presents an action research experience in Douki-Seisan in cooperation with the Nissan Factory in Barcelona. Three suppliers are involved in the experience to improve the way they perform synchro deliveries of parts to Nissan. Supplier issues are analysed and a decision making tool is developed for a supplier.

Comparative models for minimizing ergonomic risk in assembly lines

We present a new mathematical model for the assembly line balancing problem with the objective of maximizing the line comfort to operators. Besides minimizing discrepancies between the ergonomic risks of workstations, balancing is subject to temporal and spatial conditions for the workstations. To evaluate the performance of the proposed model, we compare it with other mathematical model whose objective is minimizing the maximum ergonomic risk of a mixed-model assembly line. To compare the models, a case study linked to Nissan’s engine plant in Barcelona (NMISA, Nissan Motor Iberica – BCN).

Time-based conditions for synchronized procurement in Douki Seisan

This paper introduces the synchronous manufacturing philosophy (douki seisan) devised by Nissan, and relates it to “Just in Sequence”, a common technique in current automotive industry. Literature is full of case studies, and the advantages and drawbacks of JIS have been reported. However, no attempt to model the necessary relations to make this system work has been found. In this paper, the necessary conditions concerning the lead times and cycle times of the different activities are deduced, and even the moment when they should take place. They allow us to define a strongly synchronous system. For practitioners, each condition shows opportunities for process improvement. For researchers, lack of compliance with such conditions, gives rise to maximum satisfiability problems.

Minimizing lost-work costs in a mixed-model assembly line

Mixed-model assembly lines present two issues due to differences in processing times from product types; these issues are the work overload or unfinished work and the useless time or unproductive time. Within this context, we present, in this paper, a new mathematical model for the mixed-model sequencing problem. This model minimizes the costs by lost production and idle productive time. The model also allows processors carry out their workload with a factor activity greater than the normal, in order to reduce the work overload if it is necessary. Obviously it is also considered to provide economic compensation to workers based on their level of activation. Finally, the model is evaluated by a computational experience linked to a real case from the automotive industry.