Severity, Occurrence, and Detection: Understanding the Key Elements of FMEA

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Failure Modes and Effects Analysis is the most of commonly used various types of the industries for the Risk Management system, where simple quantification of the risk is insufficient. FMEA is the one of the most useful and effective tools for the developing designs, processes and the services. The goal of Failure Modes and Effects Analysis is to align the risks as the closely as possible with its source. This enables the determination of the root cause of the risk base, and allows the selection of the ways to detect the occurrence of a particular failure and to find options to the prevent or mitigate the effects of a particular failure. Good Failure Modes and Effects Analysis methodology allows the identification and the documentation of the potential failures of the system and their resulting effects on its. It is also allows for the assessment of the potential failure to be determine actions that would reduce the severity, reduce occurrence, and the increase detection.

During Failure Modes and Effects Analysis, all steps are the analysed for potential failure opportunities, the ultimate effect to the product quality or patient safety and efficacy as the result of each potential failure opportunity is then quantified, and then adjusted based on the capabilities to detect or mitigate, to the reach a final assigned score of risk.. The risk for the each failure is often times entered into the risk score matrix which the enables easy determination of the priority and the level of attention required to be applied to each the step based on total risk priority number (RPN). The outcome of the Failure Modes and Effects Analysis is the list of recommendations to be reduce overall risk to an acceptable level, and can be the used as a source for the designing a control strategy.

Failure modes and effects analysis (FMEA) is a step-by-step approach for identifying all possible failures in a design, a manufacturing or assembly process, or a product or service.

  1. FMEA Stand for Failure Mode and Effective Analysis
  2. FMEA analysis the potential failure of a product or a process that affects the function partially or completely
  3. It evaluates the severity of the effects as a result of that failure, chances of occurrence and the current controls available to detect or prevent the failure.
  4.  It is an analytical technique (a paper test) that combine the technology and experience of the couple
  5. Identifies foreseeable failure mode of a product or process and planning for its elimination and document the whole process of risk analysis.
What is FMEA

Evolution of FMEA

  1. Introduced in late 1940s for military usage by US armed forces.
  2. Later used for aerospace/rocket development to avoid error due to small sample sizes of costly rocket technology.
  3.  Also used as application for food safety for the Apollo Space program, and later in the food industries in general
  4.  Primary push came in 1960, while developing the means to put a man on the moon and return him safety to earth.
  5. 1970S Ford motor company introduced to the automotive industry for safety and regulatory consideration.
  6.  Ford also used FMEA to improve production and design.

What are the Types of FMEA

  • Design FMEA

The Design failure mode and analysis aids in the design process by the identifying known and foreseeable failure modes and then ranking failures according to relative impact on the product. Design FMEA focuses on relative impact of the failure mode on the product.

The Design failure mode and analysis is the analytical technique utilized the primarily by the design responsible engineer and team it means that assure that, to the extent possible, potential Failure Modes and their associated failure Causes Mechanisms have been to be considered and the addressed. End items, along with the every related system, subassembly and the component, should be the evaluated. In its most of rigorous form, an FMEA is the summary of the team’s thoughts including an analysis of the items that could go to wrong based on the experience as a component, subsystem, and system is designed. This is the systematic approach parallels, formalizes, and the documents the mental disciplines that an engineer normally goes to through in any design processes.

The responsible design engineer has the disposal the number of the documents that will be the useful in preparing the Design FMEA process. The process begins by the developing a listing of what the design is can expected to the do, and the what it is expected not to do the i.e., the design intent.

Customer wants to  and needs should be the incorporated, which may be determined from the sources such as the Quality Function Deployment QFD, Vehicle Requirements Documents, known product requirements, and & or manufacturing & assembly & service & recycling requirements. The better definition of the desired characteristics, the easier it is to identify the potential Failure Modes for the preventive and the corrective action.

  • Process FMEA

Process FMEA identifies potential process failure and helping to establish priorities according to the relative impact on the internal or external customer. Process FMEA Focuses on the relative impact of the failure mode on internal or external customer.

Types of FMEA

Advantages of FMEA

  • Catalyst for the teamwork and idea exchange between the functions
  • Collect the information to the reduce future failures, capture the engineering knowledge
  • Early identification and the elimination of potential failure modes effect
  • Emphasize problem prevention
  • Improve company image and competitiveness
  • Improve production yield
  • Improve the quality, reliability, and safety of a product/process
  • Increase user satisfaction
  • Maximize profit
  • Minimize late changes and associated cost
  • Reduce impact on company profit margin
  • Reduce system development time and cost
  • Reduce the possibility of the same kind of failure mode in future
  • Reduce the potential for warranty concerns.

FMEA Procedure

  • For the each process input (start with high value inputs), determine the ways in which the input can be go wrong (failure mode)
  • For each failure mode, determine effects, Select the severity level for the each effect
  • Identify the potential causes of the each failure mode, Select the occurrence level for each the cause
  • List current controls for each cause, Select the detection level for the each cause
  • Calculate the Risk Priority Number (RPN)
  • Develop the recommended actions, assign responsible persons, and take the actions, Give priority to high RPNs ,Must be the look at severities rated a 10
  • The assign predicted severity, occurrence, and the detection levels and compare to RPNs.

Application Examples

  • Manufacturing: The manager is responsible for the moving a manufacturing operation to a new facility. He/she wants to be sure the move goes as smoothly as possible and that there are no any surprises.
  • Design: A design engineer wants to be think of all the possible ways of product being designed could fail so that robustness can be built into the product part design.
  • Software: A software engineer wants to be think of possible problems in the software product could fail when scaled up to large databases. This is the core issue for the Internet.

When to Conduct an FMEA

  • Early in the process improvement investigation that time conduct FMEA
  • When the new systems, products, and processes are being to be designed
  • When the existing designs and processes are being to be changed
  • When the carry-over designs are be used in the new applications
  • After the system, product and process functions are as defined, but the before specific hardware is selected or released to the manufacturing.

Why Use a FMEA – Continued

  • Improves the quality product, reliability and the safety of products and processes in a proactive manner.
  • Helps to the increase customer satisfaction, by proactively addressing failures that can be keep us from meeting critical customer requirements in processes and products.
  • Reduces the product development timing and cost of product
  • Reduces the operational risk
  • Documents and tracks actions taken to reduce  the risk; Prioritize areas of the focus.

What Severity, Occurrence, and Detection

  • Severity:- Importance of the effect on the customer requirements
  • Occurrence:- Frequency with which a given the cause occurs and
    creates failure modes analysis (obtain from the past data if possible)
  • Detection:- The ability of the current control scheme to detect the parts
    (then prevent) a given cause (may be the difficult to estimate early in process the operations).

Risk Priority Number (RPN)

RPN number is the product of the severity, occurrence, and detection scores.

RPN = Severity x Occurrence x Detection

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