FMEA Analysis | Detailed Guide

Rahul Kashyap

FMEA Analysis | Detailed Guide 

FMEA Analysis
Failure Mode and Effects Analysis (FMEA) is a structured approach to discover potential failures that may exist within the design of a product or process. Failure Mode are the ways in which a process may fail. Effects are ways that these failures can result in waste, defects or harmful consequences for the customer. Failure Mode and Effects Analysis (FMEA) is designed to identify, prioritize, and limit these Failure Mode.
FMEA is not a good engineering option. Rather, it enhances good engineering by applying the knowledge and experience of a cross functional team (CFT) to assess the design progress of a product or process by assessing the risk of failure.
A design initiated by the US Army, Failure Mode and Impact Analysis (FMEA) in the 1940s, is a step-by-step approach to identifying all possible failures in a manufacturing or assembly process, or a product or service. It is a common process analysis tool
"Failure Mode" means the modes or modes in which something may fail. Failures are any errors or defects, particularly ones that affect the customer, and may be probable or real.
"Effect Analysis" refers to studying the consequences of those failures.
Types of FMEA

  • Design FMEA (DFMEA)
  • Process FMEA
  • Design FMEA
Design FMEA (DFMEA) explores the possibility of product malfunctions, short product lives and safety and regulatory concerns:
  • Physical Features
  • Geometry
  • Tolerances
  • Interfaces with other components and / or systems

Engineering noise: environment, user profile, degradation, system interaction

Process FMEA

Process FMEA (PFMEA) refers to failure that affects product quality, process reliability, customer dissatisfaction, and impacts arising from safety or environmental hazards:
  • Human factor
  • Methods while processing
  • Material Used
  • Machines Used
  • Measurement system influences acceptance
  • Environmental factors on process performance

Why Perform Failure Mode and Effects Analysis (FMEA Analysis)

Historically, the sooner a failure is discovered, the less it will cost. If delays in product development or launch are detected, the effect is exponentially more devastating.
  • Multiple options to reduce risk
  • High ability to validate and validate changes
  • Collaboration between product and process design
  • Better Design for Manufacturing and Assembly (DFM / A)
  • Low cost solutions
  • Heritage, tribal knowledge and standard work usage
Ultimately, this methodology is effective in identifying the process and fixing it quickly, so that you can avoid the bad consequences of poor performance.
When to Perform Failure Mode and Effects Analysis (FMEA analysis)
It sometimes happens that it makes sense to perform a failure mode and impact analysis in following cases:
  • When you are Launching a new product, process or service
  • When you plan to do an existing process differently
  • When you have the goal of improving quality for a specific process
  • When you need to understand and correct the failures of a process
In addition, it is advisable to perform FMEA sometime during the lifetime of a procedure. Quality and reliability must be continuously investigated and improved for optimal results.

How to Perform Failure Mode and Effects Analysis (FMEA)

The FMEA is performed in seven stages, with important activities in each phase. Stages been set different levels to ensure that only appropriate team members are required to be present for each stage. The FMEA approach used by Quality-One has been developed to avoid specific pitfalls that make analysis slow and ineffective. Quality — A three-path model allows for prioritization of activity and efficient use of team time.

There are seven stages for the development of FMEA:

  • FMEA Pre-Work and Assemble the FMEA Team 
  • Path 1 Development (Requirements through Severity Ranking)
  • Path 2 Development (Potential Causes and Prevention Controls through Occurrence Ranking)
  • Path 3 Development (Testing and Detection Controls through Detection Ranking)
  • Action Priority & Assignment
  • Actions Taken / Design Review
  • Re-ranking RPN & Closure

FMEA Pre-Work and Assemble the FMEA Team

Pre-work involves the collection and creation of key documents. FMEA works smoothly through the stages of development when an investigation into past failures and initial documents is made from its inception. Initial documents may include:
·         Failure Mode Avoidance (FMA) Past Failure
·         Eight Discipline of Problem Solving (8D)
  • ·         Boundary / block diagram (for DFMEA)
  • ·         Parameter diagram (for DFMEA)
  • ·         Process flow diagram (for PFMEA)
  • ·         Attributes Matrix (for PFMEA)
A pre-work checklist is recommended for an efficient FMEA event. Checklist items may include:
  • ·         Requirements to be included
  • ·         Design and / or process assumptions
  • ·         Initial Bill of Materials / Components
  • ·         Known causes from surrogate products
  • ·         Probable cause from interface
  • ·         Possible reasons for design options
  • ·         Possible causes from noise and atmosphere
  • ·         Family or Baseline FMEA (Historical FMEA)
Previous testing and control methods used on similar products

Path 1 Development (Requirements through Severity Ranking)

Path 1 includes the function, failure mode, failure effects, and severity ranking. Pre-work documents help in this task by taking previously captured information to populate the first few columns of the FMEA (based on the selected worksheet).
The Work List must be written in a Work List-based context. Each function must have an associated measurable value. Tasks may include:
  • ·         Specifications of a design
  • ·         Government manual
  • ·         Program specific requirements
  • ·         Product characteristics to be analysed
  • ·         Desired process output
Failure modes are written as conflicting actions or conflicting requirements in five possible ways:
  • ·         Complete job failure
  • ·         Partial / degraded function failure
  • ·         Intermittent failure
  • ·         At work failure
  • ·         Unexpected function failure
Effects are the consequences of failure, where each individual effect is given a severity ranking. Actions are considered at this stage if the severity is 9 or 10 then
Recommended actions that can be considered affect the design of the product or process at high severity rankings (safety and regulatory) of failure modes.

Path 2 Development - (Prevention Control through Potential Causes and Prevention Rankings)

The reasons are chosen from design / process input or previous failures and, when applied to a specific failure mode, are placed in the Cause column. Completed columns in path 2 are:
·         Possible causes / mechanism of failure
·         Current prevention controls (ie standard work, previously successful design, etc.)
·         Ranking for each reason
·         Classification of special features when prompted

Path 3 Development (Testing and Detection Controls through Detection Ranking)

Path 3 development includes the inclusion of detection control that verifies whether the design meets the requirements (for design FMEA) or cause and / or failure modes that, if unspecified, can reach the customer (for process FMEA ).
·         The columns completed in Path 3 are: Detection Control and Detection Ranking
·         Actions are prescribed to improve control if they are insufficient for the risks set out in Paths 1 and 2. Recommended actions should address weaknesses in the test and / or control strategy.
·         Review and update of Design Verification Plan and Report (DVP & R) or Control Plans are also possible outcomes of Path 3.

Action Priority & Assignment

Acts previously set out in Path 1, 2 or 3 are assigned a Risk Priority Number (RPN) for action follow-up.
The RPN is calculated by multiplying the severity, occurrence, and probe rankings for each possible failure / effect, cause and control combination. Actions should not be determined based on the RPN threshold value. This is usually done and is a practice that leads to poor team behavior. Completed columns are:
  • ·         Review recommended actions and assign RPNs for additional follow-up
  • ·         Assign action to appropriate personnel
  • ·         Assign action on due dates

Actions Taken / Design Review)

The FMEA action is terminated when counter measures have been taken and are successful in reducing the risk. The purpose of an FMEA is to discover and mitigate risk. The risks that FMEA does not pose are considered weak and non-value-added. The team effort did not improve and hence the analysis was result in wasted time.

Re-Ranking RPN and Closure

After successful confirmation of risk mitigation actions, the core team or team leader will re-rank the appropriate ranking value (severity, occurrence, or detection). The new ranking will be multiplied to obtain a new RPN. The original RPN is compared to the modified RPN and the relative improvement of the design or process has been confirmed. Columns completed in step 7:
  • Re-ranked Severity
  • Re-ranked Occurrence
  • Re-ranked Detection
  • Re-ranked RPN
  • Generate new Actions, repeating Step 5, until risk has been mitigated
  • Comparison of initial RPN and revised RPN

Post a Comment

Post a Comment (0)