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DFMEA : Design Failure Mode & Effect Analysis

What is DFMEA

DFMEA (Design Failure Mode & Effect Analysis) is a part of FMEA (Failure Mode & Effect Analysis) used for identifying potential risks involved in a new design of a product or service. During DFMEA product design functions, failure modes, cause of failure and their effects with corresponding severity ranking, occurrence and detection is identified. 

DFMEA helps in identification of the effects of failures, actions that could eliminate or reduce the chances of the failures and provides a written record of the work performed.

 


Why DFMEA is Required

Any New design or Service involves some risks. Identifying risk and mitigation plan in initial design stage is a good practice. DFMEA helps in reducing the chances of failure and product time to market.

 


DFMEA Process

DFMEA of a product or service involves 10 major steps.

Step 1 : Design Review

  • Product Design is reviewed to identify each component and its relation with other components.
  • Design review is done to make sure each team member is aware of product and its design, identifying main design components and their function and all components in DFMEA Scope.

 

Step 2 : Brainstorm & List Out Potential Failure Mode

  • All potential design failure mode for each component are identified and documented. Potential failure mode for any component is a condition where it could fail to perform its intended functions.
  • Previous customer complaints and market response is also used to find out potential failure modes.

 

Step 3 : List Potential Effects of Failure modes

  • Potential effects of failure need to be identified and listed. There can be one or more effects of any failure.
  • Effect of Potential  failures need to be defined in terms of product performance, function, effect on Customer, Environment or Cost.

 

Step 4 : Define Severity For Each Effect of Potential Failure Mode

  • Severity ranking is an estimate of seriousness of any effect of failure mode.
  • Severity ranking is given based on relative scale from 1 to 10 ("10" for an accident, safety issue or failure without warning and "1" for very less risk)

 

Step 5 : Define Occurrence Ranking For Each Potential Cause

  • Occurrence ranking is an estimate of how frequently the cause of failure is likely to happen. We need to find out potential cause, frequency of occurrence of that cause to determine the occurrence ranking.
  • Occurrence ranking is given based on relative scale from 1 to 10 ("10" means failure is happening very frequently and "1" is for rare)
  • Occurrence Ranking can be time based, number based or event based.

 

Step 6 : Define Detection Ranking For Each Potential Cause

  • Detection ranking is based on the chances of the detection of failure. Detection Ranking is an ability of controlling the design and process to detect the failure.
  • Detection ranking is given based on relative scale from 1 to 10 ("10" means its very difficult to detect the failure and "1" if its easy to detect the failure)
  • Occurrence Ranking can be time based, number based or event based.

 

Step 7 : Calculate RPN (Risk Priority Number)
 
RPN = Severity X Occurrence X Detection
 
  • RPN gives us a relative risk ranking. Higher the RPN means higher Risk. RPN number is calculated for each failure mode. Depending on RPN Value we can prioritize efforts.

 

 
Step 8 : Action Items to Reduce Value Of RPN Number
  • RPN value can be reduced by reducing any ranking value e.g. severity, occurrence or detection 
  • Severity value can be reduced with change in design
  • Occurrence value can be reduced by controlling the potential causes of failure of a function
  • Detection value can be reduced with improving prevention and detection of cause

 

Step 9 : Actions Plan
  • Steps that are required to reduce the value of RPN number are outlined.
  • Responsibilities and timelines for the action plan are defined.‚Äč

 

Step 10 : Calculate Final RPN
  • All failure modes are reevaluated with all improvements done. RPN value is recalculated to make sure everything is ok.

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