| 1. |
- Fotedar, Sunney, 1989, et al.
(författare)
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Mathematical optimization of the tactical allocation of machining resources for an efficient capacity utilization in aerospace component manufacturing
- 2019
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Ingår i: Proceedings of the 10th Aerospace Technology Congress. - : Linköping University Electronic Press. - 1650-3686 .- 1650-3740. - 9789175190068 ; , s. 183-188
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Konferensbidrag (refereegranskat)abstract
- In the aerospace industry, with low volumes and many products, there is a critical need to efficiently use available manufacturing resources. Currently, at GKN Aerospace, resource allocation decisions that in many cases will last for several years are to some extent made with a short-term focus so as to minimize machining time, which results in a too high load on the most capable machines, and too low load on the less capable ones. This creates an imbalance in capacity utilization that leads to unnecessary queuing at some machines, resulting in long lead times and in an increase in tied-up capital. Tactical resource allocation on the medium to long-range planning horizon (six months to several years) aims to address this issue by allocating resources to meet the predicted future demand as effectively as possible, in order to ensure long range profitability. Our intent is to use mathematical optimization to find the best possible allocations.
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| 2. |
- Thörnblad, Karin, 1971, et al.
(författare)
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Scheduling optimization of a real flexible job shop including fixture availability and preventive maintenance
- 2015
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Ingår i: European Journal of Industrial Engineering. - 1751-5254. ; 9:1, s. 126-145
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Tidskriftsartikel (refereegranskat)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 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.
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| 3. |
- Thörnblad, Karin, 1971, et al.
(författare)
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Scheduling optimization of a real flexible job shop including side constraints regarding maintenance, fixtures, and night shifts
- 2015
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Ingår i: Proceedings of the 7th Multidisciplinary International Conference on Scheduling: Theory and Applications (MISTA 2015). 25 -28 Aug 2015, Prague, Czech Republic. - 2305-249X. ; , s. 78-101
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Konferensbidrag (refereegranskat)abstract
- We present a generic iterative procedure for the scheduling of a real flexible job shop, the so-called multitask cell at GKN Aerospace Engine Systems in Sweden. A time-indexed formulation of the scheduling problem is presented—including side constraints regarding preventive maintenance, fixture availability, and unmanned night shifts. This paper continues the work in ”Scheduling optimization of a real flexible job shop including fixture availability and preventive maintenance” [Thörnblad et al., European Journal of Industrial Engineering, 2015], with an improvement of the iterative solution procedure, and the inclusion of constraints regarding night shifts during which only unmanned processing is allowed to be scheduled. Schedules resulting from our procedure and from the use of two priority dispatching rules are compared. The gain of including the night shifts constraints is significant. Despite the added complexity, our methodology produces near-optimal schedules for industrial data instances for the coming shift within an acceptable practical time frame.
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| 4. |
- Vallhagen, Johan, 1965, et al.
(författare)
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Advanced use of Data as an Enabler for Adaptive Production Control using Mathematical Optimization – An Application of Industry 4.0 Principles
- 2017
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Ingår i: Procedia Manufacturing. - : Elsevier BV. - 2351-9789. ; 11, s. 663-670
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the need for more advanced and mathematically based planning and scheduling tools for production systems with complex flows which are subjected to constant change. To develop and utilise such tools, better data acquisition and aggregation from the operational level on the shop floor is needed. An information infrastructure has been proposed to enable this novel type of optimized adaptive scheduling to achieve significant improvements in production efficiency. The solution is based on a system architecture and an information infrastructure with a middleware that provides a specific production cell with all the data relevant for scheduling.
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