Failure modes and effects analysis also documents current knowledge and actions about the risks of failures, for use in continuous improvement. FMEA is used during design to prevent failures. Later it’s used for control, before and during ongoing operation of the process. Ideally, FMEA begins during the earliest conceptual stages of design and continues throughout the life of the product or service.
3. FMEA
• Failure Mode and Effect Analysis is also known as risk analysis.
• It is a preventive measure to systematically display the causes, effects
and possible actions regarding observed failures.
• Is an engineering technique used to define, identify and eliminate known
or potential failures, problem, errors.
• It is before-the-event action
• Is a never ending process improvement tool.
4. FMEA - OBJECTIVES
1. Find failures and prevent them.
2. Priorities failures and attempts to eliminate them.
5. TYPES OF FMEA
1. System FMEA -
2. Design FMEA - Design FMEA
3. Process FMEA -
4. Service FMEA -
5. Equipment FMEA - Process FMEA
6. Maintenance FMEA -
7. Concept FMEA - Design FMEA
8. Environmental FMEA - Process FMEA
6. BENEFITS OF FMEA
1. Improve product/process reliability and quality.
2. Increase customer satisfaction.
3. Early identification/elimination of failure modes.
4. Prioritize product/process deficiencies.
5. Capture engineering/organisation knowledge
6. Document and track the action taken to reduce risk
7. Focus for improved testing and development
8. Act as catalyst.
7. INPUTS FOR FMEA
1. People inputs: FMEA is a team work. The team should have assembly
engineer, manufacturing engineer, material engineer, quality engineer,
service engineer, suppliers and the customer.
■ 2. Data inputs: Product and process specifications, reliability data,
customer priority data, process variability data, process descriptions and
inspection data.
8. STAGES OF FMEA
■ Stage 1: Specifying Possibilities
i) Functions
ii) ii) Possible failure mode
iii) iii) Root causes
■ iv) Effects
■ v) Detection/Prevention.
■ Stage 2: Quantifying Risks
i) Probability of cause
ii) ii) Severity of effect
■ iii) Effectiveness of control to prevent cause
■ iv) Risk Priority Number (RPN)
9. STAGES OF FMEA
■ Stage 3: Correcting High Risk Causes
i) Prioritizing work
ii) Detailing action
iii) Assigning action responsibility
iv) Check points on completion
■ Stage 4: Re-evaluation of Risk
■ i) Recalculation of risk priority number
10. FMEA PROCEDURE
1. Describe the product/process and its function
2. Create a block diagram of the product/process
3. Complete the header of the FMEA form worksheet
4. List product/process functions
5. Identify failure modes
■ failure mode includes corrosion failure, fatigue, deformation, cracking,
electrical short or open etc..
6. Describe the potential failure effects
■ defined as the result of a failure mode on the function of the
product/process
■ ex: injury to the user, impaired operation, poor appearance, odour, noise
etc..
11. FMEA PROCEDURE
■ 7. Establish a numerical ranking for the Severity(S) of the effect
■ S is the assessment of the seriousness of the failure effect
■ standard scale uses 1 for no effect and 10 for very serious effect.
■ 8. The CLASS column is filled
■ Used to classify any special product characteristics for components that
may require additional process controls.
■ 9. Identify the potential causes/mechanisms of failure
■ 10. The probability factor “Occurrence” (O)
■ It is the chance that one of the specific causes will occur.
■ Standard scale uses 1 to represent not likely and 10 to indicate inevitable.
12. FMEA PROCEDURE
■ 11. Identify current controls (design or process)
■ 12. Determine the likelihood of detection (D)
■ It is the assessment of the likelihood that the current controls will detect the cause
of failure mode
■ 1 used for certain of detection and 10 for uncertainty of detection.
■ 13. Review Risk Priority Number (RPN)
■ RPN = S x O x D
■ 14. Determine recommended actions
■ 15. Assign responsibility and target completion date
■ 16. Indicate action taken
■ After action, re-assess the severity, occurrence and detection and revise the RPN
■ 17. Update the FMEA
