Once the NUD Functions that a technology, product or manufacturing process must perform are identified, the Design Failure Modes & Effects Analysis (DFMEA) can be performed.

Function Tree

The Steps for generating a DFMEA:

Begin with superior concept architectures, NUD functions and NUD requirements.

1)      Develop a block diagram of the NUD design element or NUD function being analyzed.

2)      Determine ways each NUD design element or NUD function can fail. A Noise Diagram may be useful for this step.

3)      Determine the effects of each failure on the customer.

4)      Identify potential causes of each failure mode. Use the Noise Diagram to help.

5)      List the current design controls (see below) for each cause or failure mode.

6)      Create severity, occurrence, and detection rating scales for each cause or failure mode under evaluation.

7)      Assign severity, occurrence, and detection ratings to each cause.

8)      Calculate Risk Priority Numbers (RPN) for each cause.

9)      Determine recommended actions in the form of additional design controls to reduce high RPN's.

10)  Apply design control tools and best practices to reduce sensitivity to root causes of failure or eliminate root causes of failure. Re-calculate RPN's.

The causes of failure will be qualitatively and quantitatively documented and corrective action should be underway. Recalculate the RPN's after corrective action results.

Design Controls

There are five standard forms of design controls:

1)      Computer-Aided Engineering

2)      Computer-Aided Design

3)      Characterization Studies

4)      Designed Experiments (DOE) and Robust Design

5)      Verification / Validation Tests

The table below illustrates a standard format for DFMEA

Noise Diagrams and Fishbone Diagrams are often helpful during the identification of failure modes and root causes within a DFMEA table by identifying what can go wrong and the mechanisms of how it goes wrong. These tools are illustrated in QG10 and QG11.