DFMEA Example

The failure mode could potentially lead to deteriorated door panel life (a failure mode effect of door panel corrosion), resulting in poor appearance and impaired function of the interior door hardware.Note: it is acceptable to break down the effect in a chain of events as shown if it better describes the problem being worked on. The effect is described from the perspective of the customer, although the description need not be in the customer’s’ language.  The severity of the deteriorated door life effect is rated as a 6 here.

There are 4 potential design-based root causes of the door panel corrosion (the failure mode here) listed. Note that while these causes may show up in fabrication or assembly, they are design-based, that is, the designers specify their values or settings. Each cause receives its own probability of occurrence rating score, based on the likelihood of the cause happening and its resulting in the failure mode.

The only design verifications (DVs) presently in place are the Design group’s phase design reviews. The ability of the design reviews to prevent the design-based cause (or detect the potential failure mode) from happening is assessed for each of the causes listed.

Then the RPN is calculated for each cause so that their corrective/preventive actions can be prioritized. The highest scores become the highest priorities. The fact that none of the scores is close to the maximum possible score (1000) does not mean anything. Just the relative scores are meaningful.

Design-FMEA-Example2

  • The Design FMEA (DFMEA) needs to be done early in the product design cycle, after the design concept has been selected since it needs detailed part functions; it should be continually updated as the program develops.
  • FMEA can be applied as a supporting method as part of the Concurrent Engineering development process.
  • Try for some concurrency between the Design and Process FMEAs.

The information developed from the DFMEA will provide excellent input for the earlier phases of the Concurrent Engineering or Integrated Product Development processes, and vice versa. Having some timing overlap (concurrency) between the DFMEA and the PFMEA will further reduce the Time to Market.

If an existing design, on which there is already a DFMEA, is applied in a different environment or usage, then the FMEA should be focused on the impact of the new environment or application.

Design-FMEA

The DFMEA process will be explained and demonstrated using the numbering scheme shown on the preceding blank DFMEA form. You may want to periodically refer back to this blank form as each step and column of the process is described. There will also be a flowchart that progressively develops in sequence with the numbered steps.

Design FMEA (DFMEA) Tutorial

DFMEA  – Introduction

In this DFMEA tutorial you will learn:

Completing the Design FMEA Form:

  • Identifying the Product Function
  • Identifying Potential Failure Modes
  • Identifying Potential Failure Effects
  • Determining the Severity of the Effect
  • Identifying Potential Cause(s) of the Failure Mode
  • Determining the Probability of Occurrence of the Failure Mode
  • Identifying Design Verifications for the Causes
  • Determining the Probability of Non-Detection of the Failure Mode

Using the Completed DFMEA Form:

  • calculating the Risk Priority Number (RPN)
  • determining Corrective and Preventive Actions
  • prioritizing Actions Based on the RPN

What Is A Design FMEA?

* FMEA is a method for identifying potential or known failure modes and providing corrective and preventive actions.
* The Design FMEA is a disciplined analysis of the part design with the intent to correct or prevent the design-based failure modes prior to the first production run.

The FMEA Process:

* Identify potential or known failure modes
* Identify the effects and causes of each failure mode
* Prioritize the identified failure modes based on the frequency of occurrence, the severity of the failure mode, and the likelihood of detection
* Provide for follow-up corrective and preventive actions
* Follow up

Design FMEA Process Flow

Design-FMEA-Process-Flow

These steps of the FMEA will be discussed and explained later in detail, but it is helpful to see the overall flow, at this overview level, for now. Try to match the additional following examples to this flow to give you a feel for how Design FMEAs can be used.

DFMEA-Example

For this abbreviated example, there are 4 basic functions of the car door. One way (failure mode) the door could potentially fail to perform the last 2 basic functions listed is by the interior lower door panels becoming corroded.

Further Reading: iSixSigma Definition, FMEA article on Quality One

Copyright 2005-2016 KnowledgeHills. Privacy Policy. Contact .