Papers by Keyword: Production Scheduling

Abstract: In industrial companies, production orders are distributed to production equipment using tools of production planning and scheduling (PPS). Main targets are to approach full capacity and profit maximization. As a further dimension of optimization, the demand of compressed air of individual production steps and time-varying cost of compressed air due to fluctuating electricity prices can be considered in PPS systems. Hereby it is attempted to execute production steps associated with significant demand of compressed air in times of low compressed air cost. Based on the approach, a methodology for implementation of compressed air demand into a PPS tool is developed.

Abstract: This paper presents an object-oriented modelling approach to production scheduling for FMS. The purpose of this study is to prepare a simulation tool to try a method of production scheduling that allocates jobs to the machines and cutting tools in an FMS. This model is developed by using Pharo as the language software for object-oriented programming through UML system design. This model consists of three types of classes. The first type is the Equipment-class, which related to the physical equipment in the FMS, for example machining-centers, cutting tools, pallet stocker, stacker crane. The second type is the Product-class that related to the information how to process the product. This class has sub-class such as process plan, machining operation and required cutting tools. The third class is the Production Planning and Controlling (PPC) class, which related to create the schedule to equipment. The PPC-class has sub-classes such as the daily order or job, job sequence, job allocation on machine and scheduling methods. A numerical example is provided in this paper to show that the object-oriented model for FMS and production scheduling is verified. The FMS consist of four identical machining centers and eight jobs. Each job has a process plan that requires some specific cutting tool types. The method for production scheduling in this model is Shortest Processing Time (SPT). The production scheduling performance is measured in this model.

Abstract: The method of make-to-order has gradually become the primary mode of production. It is an extremely important ability for enterprises to make production scheduling and response to the changes of customer demand agiely. Therefore, this paper mainly deals with how to evaluating order priority in the mode of make-to-order. For this question, an evaluation index system and a model of fuzzy mathematic system evaluation are established. Through empirical analysis, the model and evaluation system are found feasible and valid.

Abstract: Production scheduling and control under uncertainty is among the most persistent challenges in the field of operation management. Despite the significant amount of research in this domain, many studies still underline the gap between scheduling theory and practice. In this paper, we outline the important aspects to consider in the design and implementation of decision support systems for the scheduling task by reviewing the literature. From the identified guidelines, we examine a practical case and propose a decision support system for the production scheduling task in an actual manufacturing environment.

Abstract: In the paper the role of the decision maker in the process of production scheduling is discussed. A general procedure specifying the activities carried out within the framework of particular steps of scheduling is shown. The scope of the interactions of the decision maker in the scheduling process under conditions of real time system is commented. The purpose of this work is to present a range of knowledge and information which should have a decision maker and also the advantages and disadvantages of each method of participation. The work in this area is one of the most important steps when designing a new, dedicated scheduling system as well as during the analysis, selection and adaptation of an external one.

Abstract: Rescheduling, as a process of updating the production schedule is a very important element of production planning and control. The occurrence of events that outdate existing schedule is a typical situation in real manufacturing systems. Correct reaction to them allows maintaining the continuity of production and the value of evaluation indicators at the satisfactory level. The paper presents the general rescheduling procedure including activities taken from the occurrence of a disturbance up to introduction of the revised schedule. The procedure includes following steps: registering and identification of the event parameters, decision-making steps about the need and time for schedule correction, steps of changing the scheduling model, selection of rescheduling method, selection of a set of operations to rescheduling and also steps of the creation, selection, and implementation of the new schedule .

Abstract: Refinery units have the feature of operating inertia, long time transition period exists when production modes switch, during which product quality may decline and energy cost raises. The operating inertia have received significant attentions in actual refineries, while few literatures have given enough focus on it which is usually omitted to make scheduling easy. The core of this paper is to deal with the scheduling optimization problem of production modes switch considering operating inertia. By expression of the transition process, a mixed integer linear programming model was built based on a continuous time representation. The model optimizes unit operations by minimizing energy consuming. The formulation approach was used to address the scheduling of a refinery. Case study illustrates the model’s feasibility and efficiency.

Abstract: The Economic Lot Scheduling Problem (ELSP) has been well-researched for over half a century. This paper, by using extended basic period approach, offers a new algorithm which differs from previous algorithms in that every item is of different importance. Such an item, whose daily cost is very high, is considered to be of greater importance and is called “key item”; and such an item, whose total production time per times is long, is considered to be of greater importance and is called “obstacle item”. By making key items’ multipliers to be of good compatibility and loading obstacle items preferentially, new algorithm can offer good solution.

Abstract: The autoclave moulding process of composites is characterized by reentrance, capacity and time constraints. Its scheduling directly affects productivity and production cycle of composites. Scheduling methods in the existing literature can't meet the requirements of its scheduling optimization. Aiming at improving utilization and reducing energy consumption of autoclave, based on the Theory of Constraints, a heuristic algorithm considering the capacity and time constraints is proposed to solve the scheduling problem, and priority scheduling rules are established. The studying of a case shows the effectiveness of the algorithm.

Abstract: Master production scheduling plays an important role in planning levels. The scheduling without coordination will lead to an unsatisfied result. In this paper, the master production scheduling model based on bargaining game between buyer and vendor is established to realize integrated management. The improved solution of Nash equilibrium is achieved by the bargaining game. The simulation results verified the model and algorithms effectiveness.