What is a DFMEA ? Why is it used?

Design Failure Mode Effect analysis is an important design tool for design engineers

Design Failure Mode Effect Analysis

Systems can have multiple Failure modes. Which may or may not be detrimental to safety

Although no design is 100% fail safe, it’s the job of the design engineers to record, document and design for failures which may occur during product lifetime.

Murphy's Law

“Anything that can go wrong will go wrong”

Common Generic Functional Failure mode types for mechanical systems :

  • Non function
  • Under achieve its function
  • Intermittent function
  • Degrading function
  • Not meeting level of performance required

How to document risk involved in a mechanical design?

  1. Understand the system – What are the boundaries and parameters which must be considered.
  2. Investigate What are possible Failure modes?
  3. What are the root causes of the modes and what are their effects on the product performance?
  4. How to prioritize the failures? Which pose the most risk?
  5. Develop actions to reduce the risk for certain failures?

How to prepare a DFMEA?

  1. Understand the system thoroughly.
    1. Create a Parameter diagram.
    2. Create a Boundary diagram.
  2. Document the modes of failure.
  3. Determine and investigate causes of the failures
  4. Record End -effects of the failures
  5. Assign severity, Occurrence and Detection rating
  6. Calculate the Risk (RPN score)


  • Enhance knowledge and develop better understanding of the product or system being developed
  • A systematic way of dealing with issues categorizing them and prioritizing them
  • On what basis is the product to be evaluated or validated to avoid these failure modes
  • As a reference document for preparation of testing plans – Design Verification Plans.
  • Breakdown to the most critical components of an assembly and which exact characteristics causes the failure. Which aids better control in manufacturing