# The Impact of Downtime on the Stability of the Production Schedule
## 4 Conclusions  
The scheduling process in an industrial production setting is crucial because of the optimal use of the production resources available to a given manufacturing company. Effective scheduling and allocation of available resources allow the production process to be carried out in the shortest possible time, even when there are unplanned downtimes.  
This paper presents the results of a study on determining the variability and stability of production schedules. The research was conducted on two models of the production flow system. Each of them was characterized by a different complexity of the production flow, which directly affects the stability of the production schedule execution. The arrangement of production stations is crucial for the proper execution of the production process and affects its stability in different ways. In the case of the model reflecting a stream form of production flow, the stability of the production schedule resulting from the occurrence of production disruptions was lower than when using the first production flow model. This was a direct result of the number of delayed individual production orders, of which there were significantly more in the case of the second production flow model.  
The best completion times obtained for entire sets of production orders are directly related to the selection of an appropriate method of scheduling production orders for the time variant and for the structures of the finished products and their subordinate technological operations.  
The continuity parameter considered made it possible to conclude that the scheduling rule, using the scheduling of production orders from the shortest duration, allowed for the smallest average value of this indicator to be obtained for each production flow model considered, which translates into greater stability of the production schedule. In the case of the application of scheduling rules using the scheduling of production orders from the longest duration, a correlation was observed, in which as the set of production orders increased, the average continuity parameter for the rules also increased.  
The research carried out established that the impact of production disruptions affects individual production orders to a greater extent for smaller sets of orders.  
Future research plans to undertake work to further analyze the impact on the stability of production schedules. Specifically, research is planned on predicting the need to rebuild the production schedule.  
Conceptualization, P.K. and K.Z.; methodology, K.Z.; software, P.K.; validation, P.K., K.Z. and P.R.; formal analysis, K.Z. and P.K.; investigation K.Z. and P.K.; resources, P.K. and K.Z.; data curation, P.K. and P.R.; writing--original draft preparation, K.Z., P.K. and P.R.; writing--review and editing, K.Z., P.K. and P.R.; visualization, P.K. and K.Z.; supervision, K.Z.; project administration, K.Z.; funding acquisition, K.Z. All authors have read and agreed to the published version of the manuscript.  
The presented results are derived from scientific statutory research, project number 0613/SBAD/4888, conducted by Faculty of Mechanical Engineering, Poznan University of Technology, Poland, supported by the Polish Ministry of Science and Higher Education.  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflicts of interest.