Scheduling optimization of a real flexible job shop including fixture availability and preventive maintenance
Journal article, 2015

The multitask cell at GKN Aerospace Sweden is a flexible job shop containing ten resources aimed at being flexible with regard to product mix and processing types. We present a time-indexed formulation of the problem of optimally scheduling the planned jobs on the resources, also considering a limited availability of fixtures as well as required preventive maintenance activities. The objective is to minimize a weighted sum of the completion times and tardiness for the jobs, where the tardiness weight for a given job is a non-increasing function of its due date. We propose a fast iterative approach to finding a suitable value of the length of the time horizon that needs to be set for the time-indexed formulation and which considerably influences the computation time. Computational results show that the method developed is able to produce optimal, or near-optimal, schedules for real data instances within an acceptable practical time frame.

objective weights

production planning

flexible job shop scheduling problem (FJSP)

dynamic scheduling

fixture availability

preventive maintenance

time horizon

mathematical optimization

time-indexed formulation


Karin Thörnblad

Chalmers, Mathematical Sciences, Mathematics

University of Gothenburg

Ann-Brith Strömberg

University of Gothenburg

Chalmers, Mathematical Sciences, Mathematics

Michael Patriksson

University of Gothenburg

Chalmers, Mathematical Sciences, Mathematics

Torgny Almgren

University of Gothenburg

Chalmers, Mathematical Sciences, Mathematics

European Journal of Industrial Engineering

1751-5254 (ISSN)

Vol. 9 1 126-145

Subject Categories

Production Engineering, Human Work Science and Ergonomics


Computational Mathematics

Discrete Mathematics

Driving Forces

Sustainable development

Areas of Advance




Basic sciences



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