WHAT HAVE BEEN DEVELOPED FOR LOT-SIZING AND SCHEDULING PROBLEM SINCE THE EOQ MODEL WAS INTRODUCED (original) (raw)
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Computers & Industrial Engineering, 2006
In this paper, we present an industrial problem found in a company that produces acrylic fibres to be used by the textile industry. The problem is a particular case of the discrete lot sizing and scheduling problem (DLSP). In this problem, lots of similar products must be generated and sequenced in ten unrelated parallel machines, in order to minimize tool changeovers and the quantity of fibre delivered after the required due date. The company problem is original because a changeover can occur between two lots of the same product due to tool wear. We analyse the problem in detail and present an adaptation of a heuristic found in the literature to solve it. Results obtained with the proposed heuristic are compared with results that used to be obtained by the production planner, using historical data.
IFAC-PapersOnLine, 2019
This study represents a decomposition heuristic approach for simultaneous lot sizing and scheduling problem for multiple product, multiple parallel machines with secondary resources. The motivation of the study comes from the real-world instance of a plastic injection plant at Vestel Electronics. The plastic injection plant requires plastic injection molds at the planner's disposal, in order to produce variations of products, by the compatible plastic injection machines. The variations on the molds and the mold changes on the machines bring out sequence dependent major and minor setups. Since each machine requires an operator, we have extended the formulation with workforce and shift planning. Results show that proposed heuristic yields comparable solutions to that of exact model for small and medium size instances; and provides schedules for the large size instances, for which exact model cannot find a feasible solution in the allotted time.
Lot sizing and scheduling: industrial extensions and research opportunities
International Journal of Production Research, 2011
Production planning and scheduling seeks to efficiently allocate resources while fulfilling customer requirements and market demand, often by trading-off conflicting objectives. The decisions involved are typically operational (short-term) and tactical (medium-term) planning problems, such as work force levels, production lot sizes and the sequencing of production runs.
Three Mathematical Models for a Integrated Lot Sizing and Scheduling Problem
2014
The objective of this work is to propose mathematical models for the Integrated Lot Sizing and Scheduling Problem (ILSP) considering a production process involving one stage, one machine and considering sequence dependent set up times and costs. An ilustrative example is used to study the computational behavior of the models when the instances are solved by a general purpose software.
Lot-Sizing and Scheduling Optimization Using Genetic Algorithm
2019
Simultaneous lot-sizing and scheduling problem is the problem to decide what products to be produced on which machine and in which order, as well as the quantity of each product. Problems of this type are hard to solve. Therefore, they were studied for years, and a considerable number of papers is published to solve different lotsizing and scheduling problems, specifically real-case problems. This work proposes a Real-Coded Genetic Algorithm (RCGA) with a new chromosome representation to solve a non-identical parallel machine capacitated lot-sizing and scheduling problem with sequence dependent setup times and costs, machine cost and backlogging. Such a problem can be found in real world production line at furniture manufacturer in Sweden. Backlogging is an important concept in this problem, and it is often ignored in the literature. This study implements three different types of crossover; one of them has been chosen based on numerical experiments. Four mutation operators have been combined together to allow the genetic algorithm to scan the search area and maintain genetic diversity. Other steps like initializing of the population and a reinitializing process have been designed carefully to achieve the best performance and to prevent the algorithm from trapped into the local optimum. The proposed algorithm is implemented and coded in MATLAB and tested for a set of standard medium to large-size problems taken from the literature. A variety of problems were solved to measure the impact of different characteristics of problems such as the number of periods, machines, and products on the quality of the solution provided by the proposed RCGA. To evaluate the performance of the proposed algorithm, the average deviation from the lower bound and runtime for the proposed RCGA are compared with three other algorithms from the literature. The results show that, in addition to its high computational speed, the proposed RCGA outperforms the other algorithms for non-identical parallel machine problems, while it is outperformed by the other algorithms for problems with the more identical parallel machine. The results show that the different characteristics of problem instances, like increasing setup cost, and size of the problem influence the quality of the solutions provided by the proposed RCGA negatively.
A survey of lot-sizing and scheduling models
2001
Abstract: This paper surveys Lot-Sizing and Scheduling Models emphasising single-stage cases. The objective here is to present different aspects of such models in the operational research area and notes the most common modern methods to solve them. Metaheuristic methods feature heavily in the research literature. In this work the reader will find many references, though it must be noted that the speed with which the publications in the artificial intelligence and operational research areas is increasing significantly.
Lot-Sizing and Scheduling in Multistage Production Systems
1999
This study is devoted to the organization of production in manufacturing systems producing families of products through several processing and assembly stages. An input-output approach is used to describe the multistage structure of the products. The combined lot-sizing and scheduling problem is formulated, and a nominal version of this problem is solved using the common cycle approach. An e cient technique is then proposed to adjust the real-time schedule to variations of demand and production rates.
Annals of Operations Research, 2007
The aim of this work is to propose a solution approach for a capacitated lot sizing and scheduling real problem with parallel machines and shared buffers, arising in a packaging company producing yoghurt. The problem has been formulated as a hybrid Continuous Set-up and Capacitated Lot Sizing Problem (CSLP–CLSP). A new effective two stage optimisation heuristic based on the decomposition of the problem into a lot sizing problem and a scheduling problem has been developed. An assignment of mixture to buffers is made in the first stage, and therefore the corresponding orders are scheduled on the production lines by performing a local search. Computational tests have been performed on the real data provided by the company. The heuristic exhibits near-optimal solutions, all obtained in a very short computational time.