Title: Scheduling optimisation of a real flexible job shop including fixture availability and preventive maintenance

Authors: Karin Thörnblad; Ann-Brith Strömberg; Michael Patriksson; Torgny Almgren

Addresses: Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, SE-412 96 Göteborg, Sweden; Department of Logistics Development, GKN Aerospace Engine Systems, SE-461 81 Trollhättan, Sweden ' Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, SE-412 96 Göteborg, Sweden ' Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, SE-412 96 Göteborg, Sweden ' Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg, SE-412 96 Göteborg, Sweden; Department of Logistics Development, GKN Aerospace Engine Systems, SE-461 81 Trollhättan, Sweden

Abstract: 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 minimise 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. [Received 1 October 2012; Revised 13 May 2013; Accepted 20 September 2013]

Keywords: production planning; flexible job shops; job shop scheduling; FJSP; scheduling optimisation; dynamic scheduling; preventive maintenance; fixture availability; time-indexed formulation; objective weights; time horizon; GKN Aerospace Sweden; product mix; processing types.

DOI: 10.1504/EJIE.2015.067451

European Journal of Industrial Engineering, 2015 Vol.9 No.1, pp.126 - 145

Available online: 12 Feb 2015 *

Full-text access for editors Access for subscribers Purchase this article Comment on this article