Document Type : Applicable
Authors
1 MSc., Biosystems Engineering Department., Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran
2 Assistant professor, Biosystems Engineering Department., Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran
Abstract
Introduction Considering the high use of agricultural machines in sugarcane Agro-industry company; management of maintenance and repairs is necessary. The application of agricultural mechanization and the management of machines in agriculture is responsible for improving the way of working and correct use of machines. Today, with the mechanization of agricultural systems, the timely performance of activities requires correct machine planning. For proper planning, one must know the reliability of the machines. Increasing efficiency and reliability of machines is an economic necessity. Any scheduled program to increase the reliability of machines can be effective in reducing time loss due to repairs and cause repairs to be completed on time. Therefore, in this research, according to the nature of the project of annual repairs of MF 399 tractors, in which the activities and the time of their completion are possible, the graphic evaluation and review technique (GRET) method was used. GERT's method is one of the possible network programming methods. In GERT's method, the occurrence of activities is considered possible and a percentage of probability is assigned for the occurrence of each activity.
Materials and Methods This research was conducted in the Dehkhoda Sugarcane Agro-industry Company in the crop year of 2023-2024. Dehkhoda Sugarcane Agro-industry Company has 42 Messi Ferguson 399 double differential tractors. In this research, in order to schedule annual repairs, statistics and data related to the repairs of 22 MF 399 tractors were collected and the data of other machines were used to compare the actual repair time with the calculated schedule. The 13 repair items of MF 399 tractors used in the company include: engine, clutch, gearbox, differential and rear axle, brake, rear hub, body, front axle, hydraulics, electricity and battery, wheels, service and greasing. The work breakdown structure diagram and network model of annual MF 399 tractor repairs were drawn. To extract the time distribution density function of each activity, first the available information was collected for each activity, then the time distribution density function was determined for each activity. The time to perform the activities is fuzzy and they are expressed by triangular fuzzy numbers. In this research, after scheduling, the results obtained from GERT's method were compared with the actual time spent to perform annual MF 399 tractor repairs and the appropriateness of the estimates was determined. For this purpose, in order to determine the actual time of annual MF 399 tractor repairs, among the tractors available in the mechanical equipment department of Dehkhoda Sugarcane Agro-industry Company, in the crop year 2023-2024, a sample was randomly selected and the actual duration of repairs was determined. Then the actual time to complete the operation was compared with the expected time.
Results and Discussion The time to complete the annual repairs of MF 399 tractors was estimated to be 225.93 hours using the classic GERT method. But in GERT's Fuzzy method, the time calculated for annual MF 399 tractor repairs was (295.30, 232.07, 168.73) hours. The actual duration of annual repairs for 20 tractors (out of a total of 42 tractors) in Dehkhoda Sugarcane Agro-industry Company, which were repaired during the 2023-2024 crop year, according to the information available in the technical office of the company's mechanical equipment, was determined. 29.12% of the real times for completing MF 399 tractor repairs were estimated outside the fuzzy time. Therefore, the manager of the repair unit can reduce the cost of time loss and manage the time to complete the operation in the optimal time frame by using correct planning and reducing the reasons for the delay in the operation.
Conclusion Therefore, GERT F Fuzzy's method provides the possibility to the manager of the repair unit to set the completion time in the estimated range appropriately, taking into account other effective factors involved in the operation, so that there is no disruption in the implementation of activities and on the other hand, the costs to minimize when the work is not done. It also provides the possibility to create cuts at different times and control the operation process and modify it if needed. In the real world, due to existing uncertainties, there is not enough confidence in the duration of the annual maintenance of tractors, but nevertheless, the results obtained from GERT's method in this research are close to the actual time of completion of operations and make the estimates more appropriate.
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