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Computer Aided Failure Mode andEffects Analysis (CFMEA)

S. GajendranLecturer (Selection Grade), Dept. of Production Technology, MIT, AnnaUniversity Chennai.

S. Sampath KumarProfessor and Head, Dept. of Mechanical Engg., College of Engineering,Anna University, Chennai.

ABSTRACT: Failure mode and effects analysis (FMEA) is one ofthe well known risk-assessment methodologies. FMEA was firstused in 1960’s in the aerospace industry which is now recognisedas a fundamental tool in the reliability engineering field. The majorproblems which are faced by the industries in the current scenarioare the collection of data from various departments and the timeconsumed for collection of these data. This paper presents abouta software package (FMEASOFT) that was developed for FMEAwhich will (i) reduce the time consumption for data collection(ii) reduce the manual efforts for storing, updating and retrievalof data.

Keywords: FMEA, severity, occurrence, detection, risk prioritynumber (RPN).

1. INTRODUCTIONFMEA can be described as a systematic way of identifying failuremodes of a system, item or function, and evaluating the effects ofthe failure modes. The objective is to determine the causes for thefailure modes and what could be done to eliminate or reduce thechance of failure. A bottom-up technique such as FMEA is aneffective way to identify component failures or system malfunctions,and to document the system under consideration. In the 1960’s,FMEA became a widely used reliability and safety technique in theaerospace, automotive, electronic, and nuclear industries.

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FMEA is a widely used quality improvement and risk assessmenttool in manufacturing. This risk analysis tool assumes a failure mode,which occurs in a system/component through some failure mecha-nism; the effect of this failure is then evaluated. A risk ranking isproduced in order to prioritise the attention for each of the failuremodes identified. This method determines the Risk priority Number(RPN) which is given by the product of the ratings of severity,occurrence and detection.

RPN = Severity × Occurrence × Detection. Severity is anassessment of how serious the effect of the potential failure mode ison the customer. Occurrence is an assessment of the likelihood thata particular cause will happen and result in the failure mode duringthe intended life and use of the product. Detection is an assessmentof the likelihood that the current controls (design and process) willdetect the cause of the failure mode or the failure mode itself, thuspreventing it from reaching the customer.

The FMEA analysis procedure is a tool that has been adapted inmany different ways for many different purposes. It provides aknowledge base of failure mode and corrective action informationthat can be used as a resource in future troubleshooting efforts andas a training tool for new engineers. Failure modes are sometimesdescribed as categories of failure. A potential failure mode describesthe way in which a product or process could fail to perform itsdesired function as described by the needs, wants and expectationsor the internal and external customers.

FMEA is a six sigma tool for identifying, analysing andprioritising failures and solutions. FMEA is typically used as aproblem prevention tool, to improve or consolidate the basiccustomer requirements to avoid negative customer satisfaction,especially at design level.

FMEA is a systematic team driven approach that identifiespotential failure modes in a system, product, or manufacturing/assembly operations caused by either design or manufacturingassembly process deficiencies. It also requires controls to preventor detect failure modes. FMEA is a tool used to prevent problems

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from occurring. FMEA is a tool that examines potential product orprocess failures, evaluates risk priorities and helps to determineremedial actions to avoid identified problems.

FMEA demands team work. The software which are currentlyavailable in the market provide only a little or a limited support forthe simultaneous access of data at different stages of FMEA.

FMEA is a powerful method to investigate the possible failureand functional deterioration of a machine or a system and to predictthe reliability. However it is very time-consuming and tedious toperform FMEA by conventional manual method. To overcome thisproblem computer is to be used with a suitable software packagewhich will reduce the time consumption for collection of data amongvarious departments and manual efforts for storing, updating andretrieval of data. The various steps involved in the process of carryingout FMEA are shown in the Figure 1.

2. FMEA METHODOLOGYThe various steps involved in carrying out FMEA are listed below:

(i) Identify the function (ii) Identify the failure modes (iii) Identifythe effects of the failure mode (iv) Determine severity (v) apply thefor procedure for potential consequences (vi) identify the possiblecauses (vii) determine the occurrence (viii) calculate the criticality(ix) identify the process controls (x) determine the detection (xi)calculate RPN (xii) Take actions to reduce risk.

3. NEED FOR FMEA SOFTWAREThe FMEA technique considers how the failure modes of each systemcomponent can result in system performance problems and ensuresthe appropriate safeguards against such problems that are in place.But the manual effort is more in conventional method, whereas thesoftware for FMEA can effectively reduce the manual effort in thefollowing ways:

• support for the team work.• reduces the time consumption for collection of data.

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• support for storing, updating and retrieval of data.• reduces the manual effort.• support for the simultaneous access of data.• support for large database.

4. FMEASOFTThe proposed FMEA software package was developed by usingVisual basic as front end and Microsoft access as the back end. Theinputs should be given through the front end and the data shouldbe stored in the backend.

During the creation of FMEA table the software will collect thedata from the various department modules and will automaticallygenerate the FMEA table as output as depicted in figure 1.

Figure 1: Generating the FMEA Table using the FMEA Database.

The software that was developed consists of four modulesnamely (i) store record module (ii) monthly rejection report module(iii) customer complaint report module (iv) inspection reportmodule. The Home page of the FMEA SOFT is shown in figure 1.Store record module (Figure 3) is used to recognise the assemblycode, part code, assembly name, part name of the product. Monthlyrejection report module (Figure 4) is used to get the occurrencenumber from the quality department. The customer complaint

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module (Figure 5) is used to get the new potential failure and theireffects. The inspection report (Figure 6) is used to get the detectionnumber due to the measuring instruments used in the quality controland inward inspection department. All these data are stored in theFMEA data base of this software.

Figure 2: Home Page of FMEASOFT.

Figure 3: Store Record Module.

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Figure 4: Monthly Rejection Report Module.

Figure 5: Customer Complaint Module.

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Figure 6: Inspection Report Module.

The FMEASOFT has the following features:

• create new FMEA table.• update the customer complaint.• save the created table in the database.

Figure 7: Creating the FMEA Table.

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• delete, update and retrieve FMEA table.• report of the table.• automatic mode for reading the FMEA sheet.

Figure 8: FMEA Table.

Figure 9: Customer Report.

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Figure 10: Update the FMEA Table.

Figure 11: Automatic Mode for FMEA Sheet Reading.

5. CONCLUSIONSince FMEA is a tool to be used by a team, the FMEA software systemprovides enough support for the team work required while carryingout FMEA. The simultaneous access of FMEA data by all thedepartments is very advantageous for the organisation. It substan-tially reduces the time and the human effort involved in FMEAprocess. Testing and quality control engineers can use the system to

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enter failures that they have identified for a particular product andits parts and components. In the present age of simultaneousengineering, it is very important for the FMEA procedure to becomputerised which would be much beneficial for the industries.

REFERENCE[1] Dale H. Besterfield et al., “Total Quality Management”, Pearson Education,

Inc. 1999.[2] Stamatics, D.H. et al (1995)., “Failure Mode and Effect Analysis: FMEA from

Theory to Execution”, American Society for Quality (ASQ).[3] www.fmearesearch.com.[4] www.reliasoft.com.[5] www.quality-one.com.[6] www.scis.nova.edu.