1. In the DFMEA process, the potential or known failure modes are identified, then the causes are identified, and then the effects are identified.
Answer:Incorrect. The effects are identified before the causes in the DFMEA process.
2. A DFMEA would normally contain the causes that occur in production but are due to the design and causes that are due to errors or flaws in aproduction process that was called out by the designer.
Answer:Incorrect. A DFMEA should not include causes that are due to execution errors or flaws in a production process (unless the product cannot be economically/reasonably manufactured by the process called out by the designer).
3. It is a good idea to start the PFMEA before the DFMEA is finished.
4. The following would be good examples of a part function for a light bulb – no out-of-box failures and provide bright light.
Answer:Incorrect. Better examples would be to provide 99.7% defect-free turn-on reliability, and to provide 75 watts of light for 450 hours. These are more exact, and clearer to the DFMEA team.
5. Asking “What does the customer experience as a result of the failure mode of…” or “Will the component or assembly be inoperative,intermittently operative, noisy, not durable, etc.?” are examples of questions asked in the step in which the effects are determined.
6. Asking what could happen to cause a loss of function, such as “How could this part fail?”, or “Could it break, deform, wear, corrode, bind, leak, short, open, etc.?” are examples of questions asked in the step in which the causes are determined.
Answer: Incorrect. These questions should be asked in the step in which failure modes are identified.
7. When describing the effects, it is important to use the customer’s terminology.
Answer: Incorrect. Use the perspective of the external or internal customer, but it isn’t necessary to use the customer’s terminology here.
8. Do not consider the likelihood that the defect will occur in scoring the severity rating criterion.
9. In the DFMEA process, the potential or known failure modes are identified, then the causes are identified, and then the effects are identified.
Answer: Incorrect. The effects are identified before the causes in the DFMEA process.
10. Generally, to reduce the probability of the failure mode happening, better design verifications/controls will be required.
Answer: Incorrect. Generally, to reduce the probability of the failure mode happening, a design change will be required.
11. For the Occurrence rating, a 1 reflects a remote possibility of it happening and a 10 indicates a high probability of the cause and its failure occurring in major proportions.
12. If none of failure mode causes are rated high, e.g., none have RPN scores over 500 or 600, then there is a good chance you missed some key failure modes or causes.
Answer: Incorrect. The absolute RPN scores do not mean anything. The relative ranking provides prioritization of the cause’s preventive/corrective action.
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