探討運用FMEA及QFD方法於高壓氣體鋼瓶製程中不良因素分析之研究

A Study of the Application of FMEA and QFD for the Analysis of the Cause of Defection in the Manufacturing Process of High Pressure Air Cylinder

陳琬渝(Wan-Yu Chen)

指導教授 ： 胡伯潛

國立虎尾科技大學/管理學院/工業工程與管理研究所/碩士(2011年)

摘要

對於企業而言，要在競爭日益激烈的環境中維持基本的生存能力，必須以多元化的產品來滿足消費者的需求，近年來由於消費者對於生活品質的要求趨於嚴格，且往往會因為個人的喜好來決定產品的生命週期，因此產品推陳出新的速度也必須隨著市場的變化而有所調整，產品品質的問題儼然已經成為企業是否能在競爭環境中生存的關鍵因素。本研究以個案公司高壓氣體鋼瓶製程中產生失效問題進行分析，提出整合失效模式與效應分析及品質機能展開兩種方法，找出造成製程失效問題之主要關鍵因素。
目前許多研究中，失效模式與效應分析(FMEA)及品質機能展開(QFD)相關文獻分別被許多學者提出來討論，品質機能展開常被利用於新產品的開發上，雖然能有效的將顧客需求經由展開表找出產品設計初期的問題，進而提出改善以縮短開發所需要的時間，但由於其技術未能考慮產品在生產製造過程中可能產生的失效問題，以致於當產品投入生產製造時，問題仍會不斷的發生；本研究整合FMEA及QFD的方法，運用失效模式與效應分析中之風險優先數值(RPN)，計算出嚴重度(S)、發生度(O)及難檢度(D)之分數，再經由修正後得到RPN調整係數，依照個案公司近三年內得到之品質異常單及顧客意見回饋，由業務及品保部門人員進行開會討論，列出顧客對於高壓氣體鋼瓶之品質需求，與製程作業順序進行相關影響程度評比以得到品質權重指數(aj)，同時在品質機能展開表中增加了FMEA的RPN調整係數，使得FMEA分析表中的資訊透過RPN調整係數直接回饋至品質機能展開表之內，並且依照製程評比權重的不同，對於製程不良因素進行排列關係，以得到最終影響製程的主要關鍵因素。
研究結果顯示，在鋼瓶縮口製程中「瓶口R角過高」之失效問題，其製程評比權重為48.799，於整體製程失效問題中佔了最高的比例，這表示此階段製程是造成產品產生不良之最關鍵因素，生產管理者必須找出造成縮口製程產生失效問題的原因，才能對此失效問題進行改善。

關鍵字

高壓氣體鋼瓶 ； 失效模式與效應分析(FMEA) ； 品質機能展開(QFD) ； 品質權重指數(aj) ； 風險優先數值(RPN) ； RPN調整係數

並列摘要

In order to maintain the basic viability in the increasingly competitive environment, business must offer a wide range of products to meet consumer demands. In recent years, consumers become more stringent for the quality of life, and their personal preferences often determine the product life cycle. Therefore, the speed of product innovation must keep up with the changing pace of the market and the quality of product becomes the key factor of whether a company can survive in a competitive environment. In this study, the manufacturing process of the high pressure air cylinder of the case company is anlysized and an integral failure mode and effect analysis (FMEA ) and quality function deployment (QFD) method is used to identify the key factors of the failure of the manufacturing process.
Many literatures of FMEA and QFD methods have been proposed by scholars and researchers. QFD is often used in the development of new products. While it can effectively transform consumer’s demands into product design features and shorten the development time span it cannot take the failure factor of the manufacturing process into account and when the product enter the manufacturing stage some problems may recur. In this study, FMEA and QFD methods are integrated, the risk priority number (RPN) of the FMEA is used to calculate the score of the severity (S), occurrence (O), and degree of difficulty to test (D) and then modified to obtain the RPN adjustment coefficient. The sales staff and quality assurance department people will meet together and list the customer’s quality requirements of the high pressure air cylinder according to the product defect notice and customer’s feedback. They will also analyze the manufacturing process to determine the quality weighted index (aj). The study adds an FMEA RPN adjustment coefficient to the QFD that enables the information of the FMEA analysis table imply directly into the QFD. Causes of defection in the manufacturing process are sequenced according to their process appraisal weights and the main factors of influencing the manufacturing process are identified.
As the results of this study show, the process appraisal weight of the “high bottle R angle” in the necking process is 48.799 and is the highest among others which indicates the specific process is the most cirtical one in the whole manufacturing process and management needs to identify the cause of the failure occurred in the necking process and correct it effectively.

並列關鍵字

high pressure air cylinder ； Failure Mode and Effect Analysis(FMEA) ； Quality Function Deployment(QFD) ； quality weighted index (aj) ； Risk Priority Number (RPN) ； RPN adjustment coefficient.

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