Economic Bulletin of the National Mining University




Issue:2019 №2 (66)
Section:Econometrics in management decision making
Article language:Ukrainian
Title:Optimization of costs for the purchase of details for the repair of equipment at «PLC» plant of biosphere corporation
Author:Pistunov I. M., Dnipro University of Technology
Annotation:The article deals with the problem of creating such a number of spare parts for the production line producing consumer goods, so that on the one hand their number would not be excessive, and on the other hand, they would be enough in case of failure of parts in the working equipment. In this case, we analyzed the possibility of using Wilson’s formula and the statistical method of stock optimization refuted them. Instead, we identified a promising direction for solving this problem through statistical studies of the frequency of failure of certain types of parts. We created an optimization model of stocks of parts of production lines for the production of consumer goods. The use of real data from the «PLC» enterprise (Biosphere Corp.) has made it possible to find the probability of failure of 29 types of parts within the month. We have developed an optimization model based on reliability theory that includes the cost of the spare part, the probability of failure, the number of major and spare parts. To find the probability of failure-free operation of the reserve unit, we used a discrete formula for reliability theory. To ensure the use of this formula in the Solver subroutine of the Microsoft Excel electronic processor, the probability values for the following range were calculated: the number of basic parts n = [1, 29], the spare parts m = [1, 5], the failure probability p = [0, 07; 0,29]. An optimal plan for a three-factor experiment was used to reduce the number of calculations, which allowed the obtained data to be approximated by a second-order polynomial. The optimal inventory plan, which was calculated from the developed model, was tested for production during Q4 2018. The effectiveness of the proposed plan for the purchase of spare parts resulted in an overall economic effect of UAH 26.2 thousand. The outlined directions of further work include enhancing the developed model with the parameters of wages, materials, electricity, time for replacement of details and conducting of expert survey to determine the acceptable level of failure-free operation. 
Keywords:Inventory optimization, Statistical studies, Probability of failure, Probability of uptime, Experiment planning, Economic effect, Consumer goods
File of the article:EV20192_151-159.pdf
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