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Failure Mode and Effect Analysis
(FMEA)
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FMEA The aim of FMEA is to anticipate: What might fail
What effect this failure would have What might cause the failure
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FMEA The significance of the failure is assessed against:
The probability of failure An assessment of the severity of the effect of that failure The probability of existing quality systems spotting the failure before it occurs
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Potential Applications for FMEA
Component Proving Process Outsourcing / Resourcing of product Develop Suppliers to achieve Quality Renaissance / Scorecard Targets Major Process / Equipment / Technology Changes Cost Reductions New Product / Design Analysis Assist in analysis of a flat pareto chart
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Tools for meeting FMEA objectives
Benchmarking customer warranty reports design checklist or guidelines field complaints internal failure analysis internal test standards lessons learned returned material reports Expert knowledge
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Where Does FMEA Occur? Concept FMEA Design FMEA Process FMEA Planning
Development System-Level Design Detail Design Testing and Refinement Production Ramp-Up Concept FMEA Design FMEA Process FMEA
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FMEA Levels CFMEA – 1 (Concept) DFMEA – 2 (Design) PFMEA – 3 (Process)
Failures in the concept (inability to achieve performance) Detection Ability to find the failures (i.e., use of historical data, early models, etc.) DFMEA – 2 (Design) Failures in current design (performance) Detection Highlighting failures during the detail design phase PFMEA – 3 (Process) Failures in production process Finding the errors in the production line
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DESIGN FMEA (DFMEA) The Design FMEA is used to analyze products before they are released to production. It focuses on potential failure modes of products caused by design deficiencies. Design FMEAs are normally done at three levels – system, subsystem, and component levels This type of FMEA is used to analyze hardware, functions or a combination
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PROCESS FMEA (PFMEA) The Process FMEA is normally used to analyze manufacturing and assembly processes at the system, subsystem or component levels. This type of FMEA focuses on potential failure modes of the process that are caused by manufacturing or assembly process deficiencies.
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10 Steps to conduct PROCESS FMEA (PFMEA)
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FMEA - Results Risk Priority Number (RPN)
RPN = Severity x Occurrence x Detection Mathematical product of the seriousness of a group of Effects (Severity), the likelihood that a Cause will create the failure associated with the Effects (Occurrence), and an ability to detect the failure before it gets to the customer (Detection) Note: S, O, and D are not equally weighted in terms of risk, and individual scales are not linear
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Criticality Criticality = Severity x Occurrence
High Severity values, coupled with high Occurrence values merit special attention Although neither RPN nor Criticality are perfect measures, they are widely used for risk assessment
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Actions Actions taken are the important part of FMEA
Change design to reduce Severity (redundancy?) Occurrence (change in design, or processes) Detection (improve ability to identify the problem before it becomes critical) Assign responsibility for action Follow up and assess result with new RPN
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FMEA Benefits Systematic way to manage risk Comprehensive Prioritizes
Problems Based on qualitative assessment Unwieldy Hard to trace through levels Not always followed up
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FMEA - General Benefits
Prevention Planning Identifies change requirements Cost reduction Increased throughput Decreased waste Decreased warranty costs Reduce non-value added operations
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Concept FMEA - Benefits
Helps select the optimum concept alternatives, or determine changes to System Design Specifications. Identifies potential failure modes caused by interactions within the concept. Increases the likelihood all potential effects of a proposed concepts failure modes are considered. Helps generate failure mode Occurrence ratings that can be used to estimate a particular concept alternatives target. Identifies system level testing requirements. Helps determine if hardware system redundancy may be required within a design proposal
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Design FMEA - Benefits Benefits
Aids in the objective evaluation of design requirements and alternatives. Increases the probability that potential failure modes and their effects on the system / product have been considered. Aids in the planning of design test and development programs. Aids in analysing field concerns, design changes and in developing advanced designs. Ranks potential failure modes according to their effect on the customer, thus prioritizing improvements and development testing. Provides an open issue format for recommending and tracking risk reducing actions. Can reduce product development timing, production start-up problems, reduce costs and enhance product quality, reliability and safety.
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Process FMEA - Benefits
As a systematic approach, the Process Potential FMEA parallels and formalizes the mental discipline that an engineer goes through in any manufacturing planning process. The Process Potential FMEA identifies potential product related process failure modes. The Process Potential FMEA assesses the potential customer effects of the failures. The Process Potential FMEA identifies potential manufacturing and/or assembly process causes. The Process Potential FMEA identifies significant process variables to focus controls for occurrence reduction and detection of failure conditions. The Process Potential FMEA develops a list of potential failure modes ranked according to their affect on the customer, thus establishing a priority system for corrective and preventive action considerations.
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Relationships (CFMEA, DFMEA, PFMEA)
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THANK YOU
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