FMEA Method (Failure Mode and Effects Analysis)

Failure Mode and Effects Analysis (FMEA) is one of failure method applied in product development, system engineering and operational management. This method is one of the tools used in the Lean Six Sigma method.

Failure mode and effects analysis (FMEA) is a team – based methodology for identifying potential problems with the new or existing designs. It is the first step of a system reliability study. FMEA is the core task in reliability engineering, safety engineering, and quality engineering. FMEA involves reviewing as many components, assemblies, and subsystem as possible to identify failure modes, and their causes and effects.

 

 

Overview to FMEA Method

FMEA is perform to analyze potential errors or failures in the system or process, and identify potentials will be classify according to the magnitude of potential failures and their effects on the process. This method helps the project team to identify potential failure modes base on past events and experiences related to similar products or processes. FMEA allows teams to design waste- free processes and minimize errors and failures.

In order to determine the components of the process that are most in need of change, FMEA includes the following steps:

• Steps in the process.


• At failure modes (What could go wrong?)


• Failure causes (Why would the failure happen?)


• What Failure effects (What would be the consequences of each failure?)

Major benefits derive from a properly implement FMEA are as follows:

1. It provides documentation in selecting design with high probability of successful operation and safety.


2. A uniform documentation method of assessing potential failure mechanism, failure modes and their impact on system operation, resulting in a list of failure modes rank according to seriousness of their system impact and likelihood of occurrence.


3. Early identification of single failure points (SFPS) and system interface problems which may be critical to mission success and/or safety.


4. An effective method for evaluating the effect of propose changes t the design and/or operational procedures on mission success and safety.


5. A basis for in – flight troubleshooting procedures and for locating performance monitoring and fault – detection devices.

Initially, FMEA was use in the manufacturing industry in the DMAIC cycle in the Lean Manufacturing project. Now the use of the Failure Mode and Effects Analysis tool has expand into the service industry.

In general, prior to FMEA, teams need to identify some information about:

• Products / goods / services


• Function


• Effect of failure / error


• The cause of the error


• Controls currently in place to prevent errors


• Recommend countermeasures


• Other relevant details

When to Use FMEA

• A process, product or service is being design or redesign, after quality function deployment.


• An existing process, product or service is being apply in a new way.


• Before developing control plans for a new or modify process.


• When improvement goals are plan for an existing process, product or service.


• When analyzing failures of an existing process, product or service.


• Periodically throughout the life of the process, product or service

Simple steps for pre-process

Steps required in performing Failure Mode and Effects Analysis (FMEA) are:

• Gather the whole team


• Set basic rules


• Gather relevant information and do reviews


• Identify the item or process to be analyze.


• Identify the functions, failures, effects, causes, and controls of each item or process that is analyze.


• Risk evaluation deals with issues or potentials identify through analysis


• Prioritize and formulate the action / solution


• Perform corrective actions and re-evaluate existing risks


• Distribute, review and update the analysis as need.

To understand the implementation of FMEA tools in various business scopes, here are some articles you can read: FMEA in transactional scope, FMEA in financial business area, FMEA in hospital, and 10 steps to FMEA.

Basic Procedure of FMEA

• 
  

  Cross Functional Team:

  
  Assemble a cross-functional team of people with diverse knowledge about the process, product or service and customer needs. Functions often include are: design, manufacturing, quality, testing, reliability, maintenance, purchasing (and suppliers), sales, marketing (and customers) and customer service.


• 
  

  Identify the scope of the FMEA:

  
  Is it for concept, system, design, process or service? What are the boundaries? How detail should we be? Use flowcharts to identify the scope and to make sure every team member understands it in detail. (From here on, we’ll use the word “scope” to mean the system, design, process or service that is the subject of your FMEA.)


• 
  

  Fill in the identifying information at the top of your FMEA form.

  
  The form shows a typical format. The remaining steps ask for information that will go into the columns of the form.


• 
  

  Identify the functions of your scope.

  
  What is the purpose of this system, design, process or service? What do our customers expect it to do?” Name it with a verb follow by a noun. Usually you will break the scope into separate subsystems, items, parts, assemblies or process steps and identify the function of each.


• 
  

  For each function, identify all the ways failure could happen.

  
  These are potential failure modes. If necessary, go back and rewrite the function with more detail to be sure the failure modes show a loss of that function.


• 
  

  Identify Consequences:

  
  For each failure mode, identify all the consequences on the system, related systems, process, related processes, product, service, customer or regulations. These are potential effects of failure. Ask, “What does the customer experience because of this failure? What happens when this failure occurs?”


• 
  

  Determine how serious each effect is.

  
  This is the severity rating, or S. Severity is usually rate on a scale from 1 to 10, where 1 is insignificant and 10 is catastrophic. If a failure mode has more than one effect, write on the FMEA table only the highest severity rating for that failure mode.


• 
  

  For each failure mode, determine all the potential root causes.

  
  Use tools classify as cause analysis tool, as well as the best knowledge and experience of the team. List all possible causes for each failure mode on the FMEA form.


• 
  

  Determine Rating:

  
  For each cause, determine the occurrence rating, or O. This rating estimates the probability of failure occurring for that reason during the lifetime of your scope. Occurrence is usually rated on a scale from 1 to 10, where 1 is extremely unlikely and 10 is inevitable. On the FMEA table, list the occurrence rating for each cause.


• 
  

  Current process controls.

  
  These are tests, procedures or mechanisms that you now have in place to keep failures from reaching the customer. These controls might prevent the cause from happening, reduce the likelihood that it will happen or detect failure after the cause has already happen but before the customer is affect.


• 
  

  Control, determine the detection rating.

  
  This rating estimates how well the controls can detect either the cause or its failure mode after they have happen but before the customer is affect. Detection is usually rated on a scale from 1 to 10, where 1 means the control is absolutely certain to detect the problem and 10 means the control is certain not to detect the problem (or no control exists). On the FMEA table, list the detection rating for each cause.


• 
  

  Optional for most industries

  
  Is this failure mode associated with a critical characteristic? (Critical characteristics are measurements or indicators that reflect safety or compliance with government regulations and need special controls.) If so, a column label “Classification” receives a Y or N to show whether special controls are need. Usually, critical characteristics have a severity of 9 or 10 and occurrence and detection ratings above 3.


• 
  

  Calculations:

  
  Calculate the risk priority number, or RPN, which equals S × O × D. Also calculate Critical by multiplying severity by occurrence, S × O. These numbers provide guidance for ranking potential failures in the order they should be address.


• 
  

  Identify recommend actions.

  
  These actions may be design or process changes to lower severity or occurrence. They may be additional controls to improve detection. Also note who is responsible for the actions and target completion dates.


• As actions are complete, note results and the date on the FMEA form. Also, note new S, O or D ratings and new RPNs.

Conclusion:

The Failure Modes, Effects and Critical Analysis (FMEA / FMECA) procedure is a tool that has been adapt in many different ways for many different purposes.

It can contribute to improve designs for products and processes, resulting in higher reliability, better quality, increase safety, enhance customer satisfaction and reduce costs.

The tool can also be use to establish and optimize maintenance plans for repairable systems and/or contribute to control plans and other quality assurance procedures. It provides a knowledge base of failure mode and corrective action information that can be use as a resource in future troubleshooting efforts and as a training tool for new engineers.