What is Failure Modes and Effects Analysis (FMEA)? Maximizing Quality, System Component Analysis

  • Post last modified:17 March 2023
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  • Post category:Lean Six Sigma

What is Failure Modes and Effects Analysis (FMEA)?

Failure Modes and Effects Analysis (FMEA) is a systematic approach to identifying and evaluating potential failures or defects in a product or process and their potential impact on the customer or end user. The purpose of FMEA is to identify and prioritize potential failure modes, evaluate their severity, and implement corrective actions to prevent or mitigate the effects of failure.

Risks are inherent in processes and hence are required to be identified using a systematic procedure. One technique for identifying risks is the Failure Modes and Effect Analysis (FMEA) which is commonly deployed in Six Sigma projects.

The FMEA is a proactive tool that is designed and implemented to prevent the failure of various components of the system which are affected by processes under execution. An example of FMEA execution is found in the offices of multinational corporations. As soon as a visitor reaches the premises of an MNC office, he/she is required to enter one’s detail in a visitor’s register. This step is used to prevent an unauthorized person from entering the premises.

Maximizing Quality with FMEA

Apart from taking this proactive step, the guard, stationed at the office entrance gate calls up the person (MNC employee) whom the visitor wants to meet, and confirms the identity of the visitor. Only when the guard gets an affirmative response from the MNC employee, the visitor is allowed to enter the building. Also, the visitor is given a visitor’s card which he/ she is required to wear during his stay in the MNC office and return the card to the security staff at the time of leaving.

The FMEA is a proactive approach that deals with various compo\nents of the system. Using FMEA, the project team can delineate all possible failures, their effect on the system, the likelihood of occurrence of failure, and the probability that the failures will go undetected. With the help of the FMEA, the Cost to Quality or CTQ is determined as it relates to the classification of various characteristics and other critical variables which form input to quality parameters that must be addressed through risk determination and its prevention.

The FMEA helps in risk assessment using a systematic approach. Let us study the systematic approach for applying the FMEA. The system that is to be assessed for risk is determined. This is the most important step in the FMEA analysis process.

Without this step, the entire exercise would be futile. An example, in this case, would be conducting the FMEA for the visitors’ entry system into office premises or on the student’s admission process in a reputed college. After the system identification, various components that comprise the system and its interfaces are identified.

For example, the visitors’ entry system in the office premises comprises components and interfaces such as the guard at the main gate, visitor’s register, entrance to the main building, issue of the visitor’s card, etc. It is at these components and interfaces that the risk of failing to prevent unauthorized persons’ entry into the premises occurs.

System Component Analysis with FMEA

Once the system components have been identified, they are analyzed thoroughly in terms of the functions they perform and the failure points where risks may materialize. For example, the guard after making an entry in the visitor’s register may forget to issue the visitor card. This is a failure of the system component or the process associated with the issue of the visitor’s card.

To deal with this issue, a checklist may be constructed and displayed at appropriate vantage points which will be used by every guard before he allows the person to move to the main building. The failure of a system component is given a rating based on defined quality parameters. This rating may be in terms of numbers or qualitative terms such as high, low, moderate, etc. These rating parameters are constructed or developed based on the quality requirements of the Six Sigma project.

The failure ratings are documented to leave no space for ambiguity. For example, the likelihood of the guard’s failure to provide the visitor with a display card may have a very low rating as the visitor’s details have already been verified and entered into the visitor’s register.

Elements of Risk and RPN Calculation with FMEA

Along with the rating of risk, the likelihood of risk realization, i.e. the probability of the risk occurrence is also determined. For example, the probability of the above event, i.e. not issuing the visitor’s card is very less. Further, the process of allocating probability is dependent on several factors such as the experience of the person (allocating the probability), the impact on the business, etc.

All the criteria for allocating probability to risk are documented in the Six Sigma Charter. Also, these criteria are modified according to market dynamics and the level of risk associated with a business. Based on these parameters, appropriate corrective and preventive measures are drafted and implemented. Preventive measures are continuously modified to address market dynamics.

For example, corrective and preventive actions may include the construction of a checklist displayed at vantage locations. The guard must see this list every time a visitor reports at the main gate. In addition, this checklist must be modified from time to time.

There are three elements of risk namely, severity, probability, and detectability. Severity describes the effect of the failure mode. Probability describes the probability or likelihood of the occurrence of a failure mode. Detectability describes the possibility of detecting the causes of a failure mode before the effects of failure are felt.

For all three risk elements, a score is assigned subjectively. The greater the problem, the greater the score assigned to it. Each failure mode is assigned three different scores (for severity, probability, and detectability) which are multiplied to derive an aggregate score called Risk Priority Number (RPN). All aggregate scores are compared and the worst failure modes are addressed first. The processes or areas that have the highest RPN should be given the highest priority for corrective actions.

Article Source
  • Pyzdek, T., & Keller, P. (2010). Six Sigma Handbook (3rd Edition). New York, USA: McGraw-Hill Professional Publishing.

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