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- peer-reviewed (37)
Demands of customers for products and of the production for parts are being forecasted quite often in companies. The results are used extensively within the operational production planning and control by IT Systems like the SAP system. Hereby preferably methods based on exponential smoothing are being applied. Especially, in industrial practice it is expected that the pattern of the data change over time in such a way, that the parameters of the exponential smoothing have to be changed. In some companies thousands of items require forecasting, which is very laborious. With an adaptive method the parameters are modified in a controlled manner, as changes in the pattern occur. Two adaptive methods used in industrial practice are explained. Simulation experiments over a huge number of periods show when they should be used.
A simulation analysis of Independent Requirements Consumption in Master Production Scheduling
(2012)
This poster presents purpose and function of the Independent Requirements Consumption in Master Production Scheduling and gives recommendations for its application. The approach of hierarchical production planning and its planning problems are explained. The problem of new customer requirements information between planning periods and solving options are shown. The solving option of Independent Requirements Consumption is focus of this poster. The algorithm of the Independent Requirements Consumption that is implemented in commercial Enterprise Resource Planning (ERP) systems like the SAP system is analyzed. The methods for analyzing the effects of the Independent Requirements Consumption are outlined. The scenarios for simulation studies are stated and compared to similar investigations. The simulation studies were performed on a simulation system at IPF that contains both a production planning and control system and a production. The extent of simulation analyses outreaches similar investigations, especially because of the variety of scenarios. For scenarios in which capacity is available to a sufficient extent, advice for setting the Independent Requirements Consumption parameters is given. It is pointed out that with production constrained scenarios, the necessity to level out production leads to problems. An algorithm to determine necessary inventory levels is presented. It is stated that straight advice for Independent Requirements Consumption parameter settings might not be possible with production constrained scenarios. Further analyses with production constrained scenarios as well as investigations concerning safety stocks in combination with Independent Requirements Consumption are current and future research topics at the Innovation Center for Production Logistics and Factory Planning.
Independent Requirements Consumption in Master Production Scheduling in an Uncapacitated Environment
(2012)
Simulation based priority rules for scheduling of a flow shop with simultaneously loaded stations
(2013)
In this study, a real world flow shop with a transportation restriction is regarded. This restriction reduces the set of feasible schedules even more than the no-buffer restrictions discussed in the literature in the case of limited storage. Since this scheduling problem is integrated in the usual hierarchical planning, the tardiness is minimised. This NP-hard problem is solved by priority rules, because of the addressed dynamic environment (and a high number of jobs) at the company site. Due to the technological restrictions the real duration of a job is significantly larger than its net processing time. By a simulation of the processing time many priority rules are improved and some even significantly. With extensive simulations successful priority rules in the literature are analysed.
Demand uncertainty for master production scheduling is addressed over the last years by approaches of stochastic or robust optimisation. In this contribution a more detailed model is regarded. Instead of analysing the planning results by a cost function, and so implicitly assume that the plans are realizable, here the effects of robust master production scheduling are evaluated using a planning hierarchy that is common in industrial applications. The primary objective is to minimise tardiness of customer order deliveries, and the secondary objective is to minimise inventory of end products.