Selection of equipment to implement CM using ANP and Fuzzy TOPSIS techniques (case study in Iran Alloy Steel Company)

Dissertation for Master's Degree in Industrial Management

Abstract

Maintenance and repairs play an important role in maintaining reliability, availability, product quality, reducing risk, increasing efficiency and security of equipment. Manufacturing companies are always trying to reduce production costs. One of the basic costs of these enterprises is the cost of repairs, which mainly accounts for 15-75% of production costs, depending on the type of industry. A proper maintenance policy can play a very important role in availability and reliability, production quality, and system safety. But unfortunately, compared to production topics that are of great interest to researchers and writers, maintenance and repairs have not been given much importance. This issue is one of the reasons for the lower efficiency of the maintenance and repairs department compared to other departments. The senior managers of manufacturing companies expect the maintenance and repair department to have the most access to equipment and if an equipment stops the production line, this stop should be planned. This has forced the maintenance and repair managers to use any method to prevent the sudden stop of the equipment. One of the methods that has been widely used in the world's industries is CM [1], which is a very expensive method due to the use of special equipment. Different companies are trying to put the equipment that really needs continuous monitoring under CM. The purpose of this project is to prioritize all the sensitive equipment of the factory using scientific criteria and decision-making techniques that are currently common in the world, and according to that, determine which equipment needs continuous monitoring and which equipment will be prioritized in the next stage. Keywords: maintenance and repairs, FANP [2], CM, Iranian alloy steel, FTOPSIS [3]

[1]Condition Monitoring

[2]Fuzzy Analytic network process

[3] Fuzzy Technique For Order Preference By Similarity To Ideal Solution

Introduction

The maintenance and repair managers of different companies are always faced with the problem of how they can obtain criteria for identifying the priority of parts in maintenance and repairs and how they can prioritize these parts based on these criteria in this project It has been tried to use up-to-date decision-making methods and the use of experts from Iran Alloy Steel Company, which is the largest producer of alloy steels in the country, to obtain criteria for prioritizing the equipment of this company, and then to prioritize these equipment using decision-making techniques. It is hoped that this research can help, however small, to the artisans of this border and the world.

1-2-Problem definition

Maintenance and repairs play an important role in maintaining reliability, availability, quality of products, reducing risk, increasing efficiency and security of equipment. Manufacturing companies are always trying to reduce production costs. One of the basic costs of these enterprises is the cost of repairs, which mainly accounts for 15-75% of production costs, depending on the type of industry. A proper maintenance policy can play a very important role in system availability and reliability, production quality, and safety. But unfortunately, compared to production topics that are of great interest to researchers and writers, maintenance and repairs have not been given much importance. This issue is one of the reasons for the lower efficiency of the maintenance and repairs department compared to other departments. For example, about one third of repair costs are spent on unnecessary activities. (Mobley, 2002)

As mentioned earlier, one of the maintenance and repair methods is CM, which is a very expensive method due to the use of special equipment, and different companies are trying to put equipment that really needs continuous monitoring under CM. The problem here is that there are no fully explained criteria on which equipment can be selected, and also the importance of different equipment compared to other equipment is not clear. And the equipment does not have a special score based on importance.

Meanwhile, in case of inaccuracy in the selection of equipment, the company incurs additional costs for CM, and this also causes the selection of equipment that really should be under CM.

This is the case that in case of inaccuracy in the selection of equipment, the company will incur additional costs for the CM, and this also causes that the equipment that should be under CM is not selected, and in fact, this has caused both the company's capital to be wasted and also, in some cases, caused irreparable losses to the company due to the sudden stops of the equipment, which due to the condition of the supply of spare parts for the equipment, this damage is several

1-3- Objectives and application of research results

The purpose of this project is to prioritize all the sensitive equipment of the factory with the scientific criteria and decision-making techniques that are currently common, and according to that, determine which equipment needs continuous monitoring and which equipment will be prioritized in the next step. The real goal is to implement a maintenance and repair system based on continuous monitoring because it is never possible to put all the sensitive equipment of a company under continuous monitoring, but a prioritization of them should be done in order to be able to choose the equipment that has the highest priority based on the budget and also the infrastructure.

Increase the efficiency of the equipment (the efficiency means the ability to access the equipment)

1-3-2- Partial objectives

Identify the important indicators of maintenance and repairs

Prepare a list of the company's sensitive equipment

Prioritize the important equipment

Identify the experts at different levels of the company

1-4- Research hypotheses

The main purpose of this research is the prioritization of equipment which should be monitored. In this regard, three research questions are raised as follows:

What are the criteria based on which the equipment can be prioritized?

What is the weight of the criteria determined for prioritization?

How is the prioritization of the equipment that should be placed under CM using the given weight criteria?

1-5- Necessity and the importance of research

Currently in Iran Alloy Steel Company, one of the methods used for PM [1] is the CM method. This method, which is considered one of the advanced methods in the science of maintenance and repairs, has many advantages over the previous methods of maintenance and repairs that were explained earlier. This method has a very high reliability. This means that the probability of stopping the equipment that is subjected to this method of maintenance and repairs is very low, and at the same time, it increases the life of such equipment. Of course, the important thing is that this method requires a lot of money, and for its implementation, necessary economic calculations should be made. The implementation of this method in Iran Alloy Steel Company started in 2013 and was generally left to the contractor. The methods that are performed for CM in Iran Alloy Steel include the following:

Oil analysis

Vibration analysis of rotating equipment

Thermometry

Fluid network thickness measurement

In Iran Alloy Steel Company, the selection of equipment that should be subjected to CM was initially the responsibility of the factory inspection unit, and this unit also specified the following 9 criteria from the units Various requested the announcement of the list of equipment that should be under CM, which these 9 criteria are as follows:

The importance of the equipment and the impact of stopping the equipment on the production line

Motor power

The amount of operation during the day and night

The amount of operation in the work cycle

The amount of damage to the equipment due to a sudden stop

The amount of the ability of the equipment for imbalance (for example, high capacity fans) for imbalance).

The amount of investment or the price of the equipment

Existing limitations such as the number of equipment of the contracting party, the number of contractor personnel, the number of measuring devices, the amount of the contract

The degree of ability of the equipment for misalignment[2]

The above mentioned criteria and other criteria are used in different units to select this equipment.

The presence of molten metal inside the production systems, which in case of breakdown of the machine and transfer systems and freezing of the metal on the way, the evacuation of the frozen metal requires spending a lot of time and money. Increases equipment.