A parametric approach to logistic control within manufacturing simulation

Simulation offers a powerful way to investigate the boundaries of what can be achieved by a manufacturing system, demonstrating the impact of schedules and policy decisions such as the placement of buffers and the size of safety stocks. Unfortunately, the construction of factory models at the necessary level of detail is a time-consuming process, requiring specialist skills. This paper describes a novel approach to the representation of logistic control in the simulation of a business unit at Volvo Aero in Trollhättan, Sweden. Several innovative features were built into the model, making it possible for users who were not simulation experts to explore a broad range of scenarios. The resulting model architecture, as described in this paper, takes simulation out of the computer lab and places it in the hands of managers, as an enabler of the responsive enterprise

Bi-objective optimization of the tactical allocation of job types to machines: mathematical modeling, theoretical analysis, and numerical tests

We introduce a tactical resource allocation model for a large aerospace engine system manufacturer aimed at long-term production planning. Our model identifies the routings a product takes through the factory, and which machines should be qualified for a balanced resource loading, to reduce product lead times. We prove some important mathematical properties of the model that are used to develop a heuristic providing a good initial feasible solution. We propose a tailored approach for our class of problems combining two well-known criterion space search algorithms, the bi-directional ε-constraint method and the augmented weighted Tchebycheff method. A computational investigation comparing solution times for several solution methods is presented for 60 numerical\ua0instances

A parametric approach to logistic control within manufacturing simulation

Simulation offers a powerful way to investigate the boundaries of what can be achieved by a manufacturing system, demonstrating the impact of schedules and policy decisions such as the placement of buffers and the size of safety stocks. Unfortunately, the construction of factory models at the necessary level of detail is a time-consuming process, requiring specialist skills. This paper describes a novel approach to the representation of logistic control in the simulation of a business unit at Volvo Aero in Trollhättan, Sweden. Several innovative features were built into the model, making it possible for users who were not simulation experts to explore a broad range of scenarios. The resulting model architecture, as described in this paper, takes simulation out of the computer lab and places it in the hands of managers, as an enabler of the responsive enterprise

A criterion space decomposition approach to generalized tri-objective tactical resource allocation

We present a tri-objective mixed-integer linear programming model of the tactical resource allocation problem with inventories, called the\ua0generalized tactical resource allocation problem\ua0(GTRAP). We propose a specialized criterion space decomposition strategy, in which the projected two-dimensional criterion space is partitioned and the corresponding sub-problems are solved in parallel by application of the\ua0quadrant shrinking method\ua0(QSM) (Boland in Eur J Oper Res 260(3):873–885, 2017) for identifying non-dominated points. To obtain an efficient implementation of the parallel variant of the QSM we suggest some modifications to reduce redundancies. Our approach is tailored for the GTRAP and is shown to have superior computational performance as compared to using the QSM without parallelization when applied to industrial instances

Robust optimization of a bi‑objective tactical resource allocation problem with uncertain qualification costs

In the presence of uncertainties in the parameters of a mathematical model, optimal solutions using nominal or expected parameter values can be misleading. In practice, robust solutions to an optimization problem are desired. Although robustness is a key research topic within single-objective optimization, little attention is received within multi-objective optimization, i.e. robust multi-objective optimization. This work builds on recent work within robust multi-objective optimization and presents a new robust efficiency concept for bi-objective optimization problems with one uncertain objective. Our proposed concept and algorithmic contribution are tested on a real-world\ua0multi-item capacitated resource planning\ua0problem, appearing at a large aerospace company manufacturing high precision engine parts. Our algorithm finds all the robust efficient solutions required by the decision-makers in significantly less time than the approach of Kuhn et al. (Eur J Oper Res 252(2):418–431, 2016) on 28 of the 30 industrial instances

A parametric approach to logistic control within manufacturing simulation

Simulation offers a powerful way to investigate the boundaries of what can be achieved by a manufacturing system, demonstrating the impact of schedules and policy decisions such as the placement of buffers and the size of safety stocks. Unfortunately, the construction of factory models at the necessary level of detail is a time-consuming process, requiring specialist skills.This paper describes a novel approach to the representation of logistic control in the simulation of a business unit at Volvo Aero in Trollhättan, Sweden. Several innovative features were built into the model, making it possible for users who were not simulation experts to explore a broad range of scenarios. The resulting model architecture, as described in this paper, takes simulation out of the computer lab and places it in the hands of managers, as an enabler of the responsive enterprise

An approach to long range production and development planning with application to the Kiruna Mine, Sweden

The mining industry is increasingly oriented towards large scale mining and the planning concept of "Just in Time", which means activities starting and ending as late as possible without jeopardising production. The buffers, consisting of production blocks and development ahead of production, are then minimi. This, however, leads to a larger dependency on the quality of the output from the production systems. The Kiruna mine, Sweden, is a large scale mine and has a number of potential ore blocks with a content that varies in quality (Fe, P, K) and in quantity (ore tonnage). Ore production is restricted by operative and block sequencing constraints as well as by production requirements. A computerized planning model, based on operations research (multi period scheduling) has been developed to meet future demands on ore qualities and quantities. The model uses long range objectives, but can satisfy temporary short range demands without jeopardising the long range goals. A sub-optimal plan, made using the model, has been compared with a truly optimal plan. It is shown that, due to the unreliable information concerning the ore, the sub-optimal plan performs as well as the optimal one. The simulation process that was developed for this comparison is also used to estimate the need for production buffer blocks. Another buffer planning model is developed to determine when development work should take place in order to minimize the risk of additional costs, caused by an inability to start production on time. This algorithm considers the uncertainties in activity durations and is based on a Monte Carlo simulation using project networks and estimates the optimum development buffer.Godkänd; 1994; 20070429 (ysko

Optimering av underh\ue5llsplaner leder till strategier f\uf6r utvecklingsprojekt

Inom m\ue5nga typer av industriell verksamhet, t ex process-, kraft- och flygindustri, anv\ue4nds dyrbar produktionsutrustning som m\ue5ste vara tillg\ue4nglig i mycket h\uf6g utstr\ue4ckning eftersom produktionsstopp \ue4r mycket kostsamma. F\uf6r att dessa industrier ska kunna maximera l\uf6nsamheten m\ue5ste de kunna utnyttja produktionsstopp f\uf6r att \ue4ven utf\uf6ra b\ue4sta m\uf6jliga f\uf6rebyggande underh\ue5ll.Chalmers Matematik och Volvo Aero har tillsammans utvecklat en matematisk modell som ser till ekonomiska och funktionella samband mellan komponenter i det system som skall underh\ue5llas, samt kostnader f\uf6r underh\ue5llsaktiviteter och reservdelar. En studie utf\uf6rd i en verkstad f\uf6r underh\ue5ll av flygmotorer vid Volvo Aero visar p\ue5 en signifikant potential f\uf6r kostnadsbesparingar som till stor del beror av \uf6kade m\uf6jligheter till aktiv samordning av framtida underh\ue5ll via balansering av komponenternas livsl\ue4ngder.Studien har \ue4ven medf\uf6rt en nyttig genomlysning av systemet. Den visar att m\uf6jligheten att reducera underh\ue5llskostnader i h\uf6g grad beror p\ue5 livsl\ue4ngderna hos de i systemet ing\ue5ende komponenterna. Olika komponenter har d\ue4rf\uf6r olika potential f\uf6r reduktion av underh\ue5llskostnader. Dessa potentialer kan ber\ue4knas genom optimering av en serie modeller d\ue4r livsl\ue4ngden f\uf6r de olika delarna – var f\uf6r sig – har f\uf6rl\ue4ngts stegvis. P\ue5 detta s\ue4tt kan optimering av underh\ue5llsplaner \ue4ven utnyttjas f\uf6r att skapa beslutsunderlag f\uf6r val av utvecklingsprojekt somsyftar till att f\uf6rl\ue4nga livsl\ue4ngder hos enskilda komponenter

Optimering av underhållsplaner leder till strategier för utvecklingsprojekt

Inom många typer av industriell verksamhet, t ex process-, kraft- och flygindustri, används dyrbar produktionsutrustning som måste vara tillgänglig i mycket hög utsträckning eftersom produktionsstopp är mycket kostsamma. För att dessa industrier ska kunna maximera lönsamheten måste de kunna utnyttja produktionsstopp för att även utföra bästa möjliga förebyggande underhåll. Chalmers Matematik och Volvo Aero har tillsammans utvecklat en matematisk modell som ser till ekonomiska och funktionella samband mellan komponenter i det system som skall underhållas, samt kostnader för underhållsaktiviteter och reservdelar. En studie utförd i en verkstad för underhåll av flygmotorer vid Volvo Aero visar på en signifikant potential för kostnadsbesparingar som till stor del beror av ökade möjligheter till aktiv samordning av framtida underhåll via balansering av komponenternas livslängder. Studien har även medfört en nyttig genomlysning av systemet. Den visar att möjligheten att reducera underhållskostnader i hög grad beror på livslängderna hos de i systemet ingående komponenterna. Olika komponenter har därför olika potential för reduktion av underhållskostnader. Dessa potentialer kan beräknas genom optimering av en serie modeller där livslängden för de olika delarna – var för sig – har förlängts stegvis. På detta sätt kan optimering av underhållsplaner även utnyttjas för att skapa beslutsunderlag för val av utvecklingsprojekt som syftar till att förlänga livslängder hos enskilda komponenter