Optimal number of standby units and repair personnel in a multi-stage, multi-machine serial standby system having a repair facility with specialization

• Main Authors: Sia, Paul Charles C., Sy, Menardo Z., To, Marvin G.
• Format: text
• Language: English
• Published: Animo Repository 1996
• Subjects: Mathematical optimization; Mathematical models; Stochastic systems; Machinery > Maintenance and repair; Industrial engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/8312
• Institution: De La Salle University

A reliable production system is what propels the industries of out time to continuously grow and prosper. Maintaining its array of big dollar machinery in tip-top condition, entails a lot of devotion and hard work. A deep sense of understanding of the principles of preventive maintenance may become very helpful in keeping a reliable production system.In this paper, the proponents shall tackle another type of maintenance system which is characterized by the utilisation of spare machinery and a repair facility that specialises. Popularly called standby units, these machines shall be deployed to the different stages of production which shall replace a machine when it unexpectedly fails or breaks down. Thus this maintenance system is called a redundant system. Consequently, once a machine fails, it shall be assigned for repair to a specific maintenance department within the repair facility that restores the machine back to an as good as new condition. Thus, the facility is specialised. The production system that shall be in mind is identified by a series of stages logically configured into a serial set-up, wherein each stage shall embody a number of identical machines, all of which fail at random rates as dictated by a probability distribution. In order to keep the system in a minimum level of reliability, standby units are stocked up to replace the broken down machines. Also, repair personnel are deployed to the different repair departments within the single maintenance facility, wherein each facility have its own crew of repair personnel. In this concept, the repair personnel shall be specialising on broken machines of a certain type or nature of failure. Therefore, they are not able to fix or service machines which breaks down out of their line of work (specialization).In lieu of this situation, the proponents developed a model which closely depicts this kind of a scenario. The model seeks to determine the optimal number of standy units and repair personnel that will minimize the total cost of acquisition of standby units, deployment of repairmen and downtime, that which above all, will also keep the availability (uptime) of the system within a certain level of reliability.In the validation of the model, a supposed production system of a three stage, three department magnitude is used as an example to verify that the model has an optimal point. Since the formulated model dealth with integer decision variables, the enumeration method was used in finding the solution to the model.