This paper aims to develop a practical finite capacity MRP (FCMRP) system based on the needs of a... more This paper aims to develop a practical finite capacity MRP (FCMRP) system based on the needs of an automotive parts manufacturing company in Thailand. The approach includes a linear goal programming model to determine the optimal start time of each operation to minimize the sum of penalty points incurred by exceeding the goals of total earliness, total tardiness, and average flow-time considering the finite capacity of all work centers and precedence of operations. Important factors of the proposed FCMRP system are penalty weights and dispatching rules. Effects of these factors on the performance measures are statistically analyzed based on a real situation of an auto-part factory. Statistical results show that the dispatching rules and penalty weights have significant effects on the performance measures. The proposed FCMRP system offers a good trade- off between conflicting performance measures and results in the best weighted average performance measures when compared to conventio...
Abstract Both the topics of Computer Aided Process Planning and Production Planning in the contex... more Abstract Both the topics of Computer Aided Process Planning and Production Planning in the context of sheet metal air bending have been presented as standalone topics previously. This paper will focus on the interaction between both modules. Choices made by the ...
... presents a two–level algorithm to tackle this problem: an upper–level algorithm is used to de... more ... presents a two–level algorithm to tackle this problem: an upper–level algorithm is used to determine the most appropriate set of ... Automated Parameterisation of a Metaheuristic ... ti,last is the time from the current location of the tour to location i. A roulette wheel selection is used to ...
2008 IEEE International Conference on Industrial Engineering and Engineering Management, IEEM 2008, 2008
ABSTRACT To compete with alternative production methods, sheet metal working firms need to improv... more ABSTRACT To compete with alternative production methods, sheet metal working firms need to improve continuously. Improvement efforts do not solely focus on the production processes, but also on other aspects of the production chain. Production planning is one of those aspects that need to be optimized. The presented research focuses on production planning optimization for sheet metal shops with a cutting stage and a bending stage. The combination of the production plans of the individual processes does not result in a globally optimal production plan. Consequently, both processes need to be integrated for production planning. In this paper, an integer programming formulation is presented for the multiple-machine two-stage sheet metal shop production planning problem. Numerous real-life test cases are used to benchmark the approach against the current way of planning. To limit the computational time, a dedicated variable neighborhood search procedure is presented.
Sheet metal working remains an important industry. It is argued that, to be competitive, the comp... more Sheet metal working remains an important industry. It is argued that, to be competitive, the complete production chain needs to be optimised. Therefore, this article focuses on the optimisation of the production plan. The sheet metal shop is configured as a two-stage flow shop with laser cutting and air bending. In the literature, theoretical production planning models can be found
The general routing problem (GRP) is the problem of finding a minimum length tour, visiting a num... more The general routing problem (GRP) is the problem of finding a minimum length tour, visiting a number of specified vertices and edges in an undirected graph. In this paper, we describe how the well-known 2-opt and 3-opt local search procedures for node routing problems ...
ABSTRACT This paper deals with the analysis of a multi-item, continuous review model of a multi-l... more ABSTRACT This paper deals with the analysis of a multi-item, continuous review model of a multi-location inventory system of repairable spare parts, in which lateral and emergency shipments occur in response of stock-outs. The objective is to determine close-to-optimal stocking policies minimizing the total cost for inventory holding, lateral transshipments, and emergency shipments subject to a target level for the average waiting times at all locations. We structure the optimization problem as a combinatorial problem and four different heuristics are developed and evaluated in terms of their total costs and computation times. It is shown that the greedy-type heuristic has the best performance. A numerical study is carried out to look at the relative cost savings obtained from the use of multi-item approach and lateral transshipments.Journal of the Operational Research Society (2005) 56, 1419–1430. doi:10.1057/palgrave.jors.2601952 Published online 16 March 2005
International Journal of Production Research, 2007
ABSTRACT Mathematical models, sometimes implemented in commercial software, allow optimization of... more ABSTRACT Mathematical models, sometimes implemented in commercial software, allow optimization of individual machines based on specific criteria. For sheet-metal operations, cutting, punching, and air bending are the subject of extensive research, and both process planning and production planning can nowadays be automated to some extent. 2D cutting operations focus on minimization of waste material, and 3D bending operations focus on minimizing time-consuming setups. However, when integrating both processes, the benefits from separate machine optimization may disappear. Optimized nesting of parts at the laser can create additional setups at the pressbrake. In this paper, the use of OR techniques for integrated production planning for sheet-metal operations is analysed. An integrated production planning model is proposed, aimed at creating feasible groupings of parts while at the same time minimizing the number of time-consuming setups at the pressbrake. Simulation is used to confirm the applicability of the integrated approach. A case study is carried out to confirm the model's ability to generate feasible production plans. Those production plans are compared with a reference case, representing the current way of planning. An average makespan reduction of 4.11% is obtained, resulting in average yearly savings of about 10 days.
International Journal of Production Research, 2006
This paper discusses the planning module of system that has been developed in a research project ... more This paper discusses the planning module of system that has been developed in a research project investigating the possibilities for automatic planning of press brakes. Only limited attention has been given to production-planning problems for bending processes in the ...
International Journal of Production Economics, 2005
This paper presents an analytical model for determining spare parts stocking levels in a single-i... more This paper presents an analytical model for determining spare parts stocking levels in a single-item, multi-hub, multi-company, repairable inventory system in which complete pooling of stock is permitted among the hubs and companies. The objective is to minimize the total system cost which consists of inventory holding cost, downtime cost and transshipment cost. We develop an approximation method to compute
... Hartanto Wong, Dirk Van Oudheusden, Dirk Cattrysse TwoEchelon MultiItem Spare Parts Systems w... more ... Hartanto Wong, Dirk Van Oudheusden, Dirk Cattrysse TwoEchelon MultiItem Spare Parts Systems with Emergency Supply Flexibility and Waiting Time Constraints L/06/0010 CARDIFF BUSINESS SCHOOL WORKING PAPER SERIES ...
In this paper, we develop an analytical model to estimate several performance measures in a singl... more In this paper, we develop an analytical model to estimate several performance measures in a single-item, multi-company, repairable inventory system where complete pooling of stock is permitted among the companies. Compared to previous research, this paper is different in that both non-zero lateral transshipment time and delayed lateral transshipments are considered in the model. We model the system as a
This paper presents a new local search algorithm for the capacitated arc routing problem (CARP). ... more This paper presents a new local search algorithm for the capacitated arc routing problem (CARP). The procedure uses single vehicle moves and moves that operate on two routes, both derived from a node routing context but properly adapted to work well for arc routing ...
This paper aims to develop a practical finite capacity MRP (FCMRP) system based on the needs of a... more This paper aims to develop a practical finite capacity MRP (FCMRP) system based on the needs of an automotive parts manufacturing company in Thailand. The approach includes a linear goal programming model to determine the optimal start time of each operation to minimize the sum of penalty points incurred by exceeding the goals of total earliness, total tardiness, and average flow-time considering the finite capacity of all work centers and precedence of operations. Important factors of the proposed FCMRP system are penalty weights and dispatching rules. Effects of these factors on the performance measures are statistically analyzed based on a real situation of an auto-part factory. Statistical results show that the dispatching rules and penalty weights have significant effects on the performance measures. The proposed FCMRP system offers a good trade- off between conflicting performance measures and results in the best weighted average performance measures when compared to conventio...
Abstract Both the topics of Computer Aided Process Planning and Production Planning in the contex... more Abstract Both the topics of Computer Aided Process Planning and Production Planning in the context of sheet metal air bending have been presented as standalone topics previously. This paper will focus on the interaction between both modules. Choices made by the ...
... presents a two–level algorithm to tackle this problem: an upper–level algorithm is used to de... more ... presents a two–level algorithm to tackle this problem: an upper–level algorithm is used to determine the most appropriate set of ... Automated Parameterisation of a Metaheuristic ... ti,last is the time from the current location of the tour to location i. A roulette wheel selection is used to ...
2008 IEEE International Conference on Industrial Engineering and Engineering Management, IEEM 2008, 2008
ABSTRACT To compete with alternative production methods, sheet metal working firms need to improv... more ABSTRACT To compete with alternative production methods, sheet metal working firms need to improve continuously. Improvement efforts do not solely focus on the production processes, but also on other aspects of the production chain. Production planning is one of those aspects that need to be optimized. The presented research focuses on production planning optimization for sheet metal shops with a cutting stage and a bending stage. The combination of the production plans of the individual processes does not result in a globally optimal production plan. Consequently, both processes need to be integrated for production planning. In this paper, an integer programming formulation is presented for the multiple-machine two-stage sheet metal shop production planning problem. Numerous real-life test cases are used to benchmark the approach against the current way of planning. To limit the computational time, a dedicated variable neighborhood search procedure is presented.
Sheet metal working remains an important industry. It is argued that, to be competitive, the comp... more Sheet metal working remains an important industry. It is argued that, to be competitive, the complete production chain needs to be optimised. Therefore, this article focuses on the optimisation of the production plan. The sheet metal shop is configured as a two-stage flow shop with laser cutting and air bending. In the literature, theoretical production planning models can be found
The general routing problem (GRP) is the problem of finding a minimum length tour, visiting a num... more The general routing problem (GRP) is the problem of finding a minimum length tour, visiting a number of specified vertices and edges in an undirected graph. In this paper, we describe how the well-known 2-opt and 3-opt local search procedures for node routing problems ...
ABSTRACT This paper deals with the analysis of a multi-item, continuous review model of a multi-l... more ABSTRACT This paper deals with the analysis of a multi-item, continuous review model of a multi-location inventory system of repairable spare parts, in which lateral and emergency shipments occur in response of stock-outs. The objective is to determine close-to-optimal stocking policies minimizing the total cost for inventory holding, lateral transshipments, and emergency shipments subject to a target level for the average waiting times at all locations. We structure the optimization problem as a combinatorial problem and four different heuristics are developed and evaluated in terms of their total costs and computation times. It is shown that the greedy-type heuristic has the best performance. A numerical study is carried out to look at the relative cost savings obtained from the use of multi-item approach and lateral transshipments.Journal of the Operational Research Society (2005) 56, 1419–1430. doi:10.1057/palgrave.jors.2601952 Published online 16 March 2005
International Journal of Production Research, 2007
ABSTRACT Mathematical models, sometimes implemented in commercial software, allow optimization of... more ABSTRACT Mathematical models, sometimes implemented in commercial software, allow optimization of individual machines based on specific criteria. For sheet-metal operations, cutting, punching, and air bending are the subject of extensive research, and both process planning and production planning can nowadays be automated to some extent. 2D cutting operations focus on minimization of waste material, and 3D bending operations focus on minimizing time-consuming setups. However, when integrating both processes, the benefits from separate machine optimization may disappear. Optimized nesting of parts at the laser can create additional setups at the pressbrake. In this paper, the use of OR techniques for integrated production planning for sheet-metal operations is analysed. An integrated production planning model is proposed, aimed at creating feasible groupings of parts while at the same time minimizing the number of time-consuming setups at the pressbrake. Simulation is used to confirm the applicability of the integrated approach. A case study is carried out to confirm the model's ability to generate feasible production plans. Those production plans are compared with a reference case, representing the current way of planning. An average makespan reduction of 4.11% is obtained, resulting in average yearly savings of about 10 days.
International Journal of Production Research, 2006
This paper discusses the planning module of system that has been developed in a research project ... more This paper discusses the planning module of system that has been developed in a research project investigating the possibilities for automatic planning of press brakes. Only limited attention has been given to production-planning problems for bending processes in the ...
International Journal of Production Economics, 2005
This paper presents an analytical model for determining spare parts stocking levels in a single-i... more This paper presents an analytical model for determining spare parts stocking levels in a single-item, multi-hub, multi-company, repairable inventory system in which complete pooling of stock is permitted among the hubs and companies. The objective is to minimize the total system cost which consists of inventory holding cost, downtime cost and transshipment cost. We develop an approximation method to compute
... Hartanto Wong, Dirk Van Oudheusden, Dirk Cattrysse TwoEchelon MultiItem Spare Parts Systems w... more ... Hartanto Wong, Dirk Van Oudheusden, Dirk Cattrysse TwoEchelon MultiItem Spare Parts Systems with Emergency Supply Flexibility and Waiting Time Constraints L/06/0010 CARDIFF BUSINESS SCHOOL WORKING PAPER SERIES ...
In this paper, we develop an analytical model to estimate several performance measures in a singl... more In this paper, we develop an analytical model to estimate several performance measures in a single-item, multi-company, repairable inventory system where complete pooling of stock is permitted among the companies. Compared to previous research, this paper is different in that both non-zero lateral transshipment time and delayed lateral transshipments are considered in the model. We model the system as a
This paper presents a new local search algorithm for the capacitated arc routing problem (CARP). ... more This paper presents a new local search algorithm for the capacitated arc routing problem (CARP). The procedure uses single vehicle moves and moves that operate on two routes, both derived from a node routing context but properly adapted to work well for arc routing ...
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