Browsing by Author "Pastırmacı, Ali Kaan"

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    A method for managing the risk : a hybrid approach to FMEA
    (Bahçeşehir Üniversitesi Fen Bilimleri Enstitüsü, 2014-06) Pastırmacı, Ali Kaan; Beşkese, Ahmet
    In today’s competitive business world, companies from all sectors are aiming maximum profit with minimum effort. In order to accomplish this goal, companies can ignore or do not give importance to the potential failures that may give devastating harm to their reputation. These potential failure modes do not only endangering the health/safety of workers and their working conditions but also the reputation of the company. Therefore, companies should also take precautions for potential failure mode to fulfill the obligations of occupational health and safety (OHS) and maintain the reputation of the company. OHS concept requires a detailed and renewable risk analysis methodology. A risk analysis methodology that is used for eliminating the risk related to OHS concept should be simple, straightforward and easy to apply. Indeed, a vast majority of these failure modes can be prevented in advance. A risk analysis methodology which is suitable to the characteristic of the company may help. Risk analysis should be applied by experienced and knowledgeable analysts. In this thesis, one of the most widely used risk analysis methodologies, Failure Mode and Effect Analysis, is proposed. Failure mode and effects analysis is a widely used engineering technique for designing, identifying and eliminating known and/or potential failures, problems, errors and so on from system, design, process, and/or service before they reach the costumer (Schneider & Stamatis 1996). Unfortunately, traditional FMEA methodology has several shortcomings. This work has been planned to eliminate these shortcomings with the help of Fuzzy Analytical Hierarchy Process (Fuzzy AHP) and Grey Relational Analysis (GRA). Fuzzy AHP method is used to determine the importance weights for Decision Makers (DMs) and to calculate the criteria weights of decision factors both for First Risk Priority Number (RPN1) and Second Risk Priority Number (RPN2). RPN1 is calculated by using decision factors, occurrence, severity and detectability (O, S and D) with the help of GRA methodology. According to RPN1 values, FMEA team prioritizes the failure modes and determines the proper corrective actions. The team also determines the threshold intervals for corrective actions to make the work more realistic. Then, RPN2 is calculated by means of five additional decision factors (criteria). Criteria consider the cost, time, regulatory obligations, prevention policy of company, and reputation of company. Thanks to RPN2, a contribution to the literature is made. After that, RPN3 is obtained from the summation of RPN1 and RPN2 that are multiplied with their corresponding coefficients. Finally, FMEA team reprioritizes the corrective actions according to RPN3 values and the corrective actions are performed according to this prioritization. To demonstrate the effectiveness of the proposed methodology, a case study is applied in a yarn manufacturing company from Turkey.