FMEA – Failure Mode and Effect Analysis

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INTRODUCTION

FMEA (Failure Mode & effect Analysis) is a specific methodology to evaluate a system, design and process or services for possible ways in which failures can occur, so it will help identify actions which could eliminate or reduce the chance of failure occurring. in addition, for each of the failure’s identify an estimate is made of its effect on total system / design, its causes and its control method.

So FMEA is an analytical methodology used to ensure that potential problems is considered and addressed throughout the product and process development process (APQP- Advanced Product Quality Planning). in conclusion, its most visible result is the documentation of the collective knowledge of cross-functional teams.

FMEA follows the principle of preventing failure instead of a after treating failure recognition and –correction (failure handling) through in time identification of potential failure causes at the development phase. The costs for a change in design in an early phase of development are much lower than before the launch of the product, because the design is not fix yet.

It is the prevention-base methodology, so most effective for defect prevention. The cost of defect rectified during product/ process launch is far greater than same defect identified and rectified during design/ drawing stage itself. Therefore, It will help to reduce the number of complaints and failures after product launch and dispatch. FMEA is a structured mean for evaluating the problem that are likely to be encountered and the consequences of such problem. This is also useful for evaluating the effects of significant engineering changes or product/process designs. FMEA is one of the important quality core tool, and also mandatory requirement of APQP & PPAP (Production Part Approval Process).

HISTORY

The failure mode and effect analysis (FMEA) has been developed at the mid-sixties in the USA for the Apollo Project by the NASA. After applying that method in aeronautics and the aerospace industry, as well as in the nuclear technology, its usage had been introduced soon in the automobile industry. The FMEA finds now globally a widespread application. The FMEA  nowadays a methodical component of quality management systems for many automobile manufacturers and their suppliers.

When FMEA?

There are three basic cases for which FMEA process is to be applied, each with a different scope or focus:

Case 1: New designs, new technology, or new process. The scope of the FMEA is the complete design, technology, or process.

Case 2: Modifications to existing design or process. The scope of the FMEA should focus on the modification to design or process, possible interactions due to the modification, and field history. This can include changes in regulatory requirements.

Case 3: Use of an existing design or process in a new environment, location, application, or usage profile (including duty cycle, regulatory requirements, etc.). The scope of the FMEA should focus on the impact of the new environment, location, or application usage on the existing design or process.

Why FMEA?

  • FMEA is a systematic and reliable method for ensuring demanded product characteristics.
  • Early recognition and evaluation of possible failures already during the design- or process planning phase
  • Prioritized problem handling
  • Definition of appropriate Countermeasures (preventing or verifying)
  • FMEA documents the generated knowledge (Prevention of Repetitive Errors; Knowledge Management)
  • Increase of functional safety and reliability of products and processes.
  • Decrease of Warranty, through extension of the legal warranty period
  • Shorter Development periods
  • Adherence of Schedules
  • More efficient Manufacturing and Assembling
  • Buildup of a knowledge base within the company
  • Failure prevention instead of failure correction (early use)

FMEA is of two type

  1. Design FMEA
  2. Process FMEA

Advantages of FMEA

  • Aiding in the objective evaluation of design requirements and design alternatives.
  • Aiding in the initial design for manufacturing and assembly requirements.
  • Providing additional information to aid in the planning of thorough and efficient design test and development programs.
  • Developing a list of potential failure modes ranked according to their effect on “customers”.
  • Providing an open issue format for recommending and tracking risk reducing actions.
  • Providing future reference to aid in analyzing field concerns.

Lets Elaborate the FMEA (Failure Mode & effect Analysis) template, we have both Design & Process FMEA (Failure Mode & Effect Analysis).

Design FMEA
Process FMEA

1. FMEA NUMBER : 

Enter the FMEA document number, which may be used for tracking. And a  unique identification number for FMEA.

2. System & Sub System : 

Indicate the appropriate level of analysis and enter the name and number of the system, subsystem or component being analyzed.

2. Part No., Part Name : 

Indicate the appropriate level of analysis and enter the name and number of the system, subsystem or component being analyzed.

3. Model : 

Enter the intended model and vehicle line that will utilize and/or affected by the design / process.

4. Core Team : 

List the names of the responsible individuals and Departments which have the authority.

5. Drawing No. / Revision No.: 

It is the cell for the latest drawing release no. and the revision status of the part drawing for which the FMEA is made.

6. Design / Process Responsibility :

For Design enter the OEM, Department and group. Also include the supplier name if known, and for Process enter the name of manufacturer / Process owner.

7. FMEA Date : 

Key date is the initial FMEA due date before which the FMEA should be completed. Therefore in case of Design FMEA the key date should be before release date for production and in Process FMEA it should be before the PPAP submission or SOP date.

The next FMEA date is the date where the original FMEA completed and release.

8. Prepared By : 

Enter the name of facilitator / the group / person who prepare the FMEA.

9. Operation no., Description & Requirement: 

For Process FMEA we have to enter the operation number as per the sequence in process flow. Write the operation name / process name / Description in respective column. Then enter the process/ operation requirement in 3rd column.

Item/Function :

For Design FMEA, enter the name and item being analyzed and show the design level as indicated on drawing. Enter the function of the item to meet design intent. Include environment  issues (e.g. Temp., pressure, humidity etc.) If the item   has more than one function with different potential   modes of failure, list all the functions separately.

10. Potential Failure Mode : 

Identify and list the each failure that could potentially fail to meet the design intent. A recommended starting point is a review of past things gone wrong, concern reports and group brainstorming.

11. Potential Effect of Failure Mode :

Identify the effect of the failure mode on the function as perceived by the customer. It is stated in terms of the specific system, subsystem or component being analyzed.

12. Severity (S) : 

It is an assessment of the seriousness of the effect of the potential failure mode to the next component, system, subsystem or customer. Severity applies to the effect only. A reduction in severity ranking index can be affected only through a design change. It could be estimated on a “1” to “10” scale.

Severity is the value associated with the most serious effect for a given failure mode.

13. Classification : 

Classify any special product characteristics (e.g. Critical, key major, significant) for components, subsystem, system that may require additional process controls. Each item identified here in Design FMEA should have the special process controls identified in the Process FMEA.

14. Potential causes of failure : 

It is an indication of a design weakness, the consequences of which is the failure mode. The cause should be listed so that remedial efforts can be aimed at pertinent causes.

15. Current Design / Process Control (Prevention): 

List the prevention, design validation/verification (which will assure the design adequacy for the failure and cause under consideration. There are 3 types of design controls : 1) Prevent the cause or failure mode effect from occurring or reduce 2) Detect the cause and lead to corrective action and 3) Detect the failure mode.

  • Avoid failure cause if possible, otherwise avoid failure
  • Actions apply to design and not to hardware
  • Actions assure observation of specifications

16. Current Design / Process control (Detection)

  • Detection of failure cause
  • Tests apply to assembly or parts (Hardware)
  • Tests according to fulfillment of function and not to fulfillment of specification

17. Occurrence :

The value for occurrence evaluates the likeliness with which the cause can occur and generate a failure mode and is defined by the number of warranty cases. If the evaluated product is a new
development and there are no warranty cases the value for “Occurrence” will have to be rated
according to experiences from former projects.

A value of 10 means that the likeliness of
occurrence of failure cause is high, like if it is a new technology.

Occurrence ranking table as per AIAG is as below

18. Detection : 

Detection column is for the rank associated with the best detection control list in the Current Design / Process Control detection column.

This detection ranking table as per AIAG as below,

19. RPN:

The RPN is evidence as the risk of a failure / a failure cause.

Severity x Occurrence x Detection = Risk Priority Number

  • If the RPN is higher than a threshold-value (specified by customer or internal specification) there must follow an optimization, including one or multiple actions, to lower the risk and with that the RPN. so If the revaluation is not successful, the team will have to arrange a new action if the value of RPN is above the defined threshold-value.
  • Occurrence and detection are independent from each other.
  • A FMEA report summarizes the knowledge of a development team of the product, system or process and the risk assessment of the design.
  • It is important to know that FMEA reports are not being issue to customer as it contains expertise of the company.

19. Recommended Action(s) : 

The recommended action is the action taken on highest RPN’s, to reduce the respective occurrence & severity ranking.

20. Responsibility  :

Enter the organization and individual responsibility for the recommended action and the target completion date.

21. Action Taken  :

After the recommended actions has been implement, enter a brief description of the actual action and effective date.

22. New RPN  :

After the corrective action identified, estimate and record the resulting severity, occurrence and detection rankings to calculate resulting RPN.