Failure Mode and Effects Analysis (FMEA) Resource Center

Pitfalls and Limitations of FMEAs

Pitfall 1 | Prioritizes, Doesn’t Correct

  • The initial output of an FMEA is the prioritizing of failure modes based on their risk priority numbers.
  • This alone does not eliminate the failure mode. Additional action that might be outside the FMEA is needed.

Pitfall 2 | Only as Good as the Team

  • Identifying failure modes is a team brainstorming activity.
  • If the team forgets to list it, an important failure mode could be left alone, waiting to occur.

Pitfall 3 | Time Consuming

  • It takes time to get into the details.

Pitfall 4 | Unknown Unknowns

  • Might miss a failure mode or an effect outside the experiences of the company.

Pitfall 5 | Not Customizing Rating Scales

  • Rating scales should be meaningful to everyone in the organization.
  • The generic rating scales might be confusing to some teams.
  • Management will not be able to compare RPNs in order to prioritize activities between teams.

Pitfall 6 | Not Starting in the Design Stage

  • The earlier in the design process an FMEA is started, the better.
  • A DFMEA can catch where design verification is needed.

Pitfall 7 | Taking on Too Large a Scope

  • Taking on an entire process may be a daunting task.
  • Break a large process down into manageable chunks.

Pitfall 8 | Not Including Operators

  • Experienced operators should be on the team to add their perspective.
  • They often have good information on failure modes and on the effectiveness of control systems.
  • They might have information on occurrence as well.

Pitfall 9 | Not Including Customers

  • Customers, especially end-users, often have a better view on failure modes than internal personnel.

Pitfall 10 | Not Including Suppliers

  • Suppliers also bring an outside perspective to the team.
  • Might be able to tie your process in with theirs.

Pitfall 11 | Becoming a Full-Time Job

  • Sometimes people use an FMEA as an excuse to get out of doing their regular job.
  • You can’t afford to have people who are just conducting FMEAs.
  • Won’t get their regular work done.
  • Even if FMEAs are made their “regular” work, they will lose touch with the process and the FMEA will become mere paperwork.

Pitfall 12 | Not Using Concept of a Process

  • This will cause the team to forget some failure modes.
  • The team should brainstorm failure modes in each of People, Methods, Equipment, Materials, and Environment.

Pitfall 13 | Not Getting into the Details

  • A superficial look at the process will miss many failure modes.

Pitfall 14 | Forgetting there are Internal- and External-Related Failure Modes

  • Many FMEAs focus only on the customer requirements (specifications).
  • Sometimes internal productivity losses, equipment damage, scrap, and rework have very severe effects on the company.

Pitfall 15 | Confusing Root Cause and Failure Mode

  • Teams often have root causes as failure modes.
  • A failure mode is the failure to perform the intended function.

Pitfall 16 | Not Looking at Each Product

  • Templates are great but every product being made in a process is not exactly the same.
  • The template should be used as a starting point and each product should be evaluated:
    • Could this failure mode occur with this product?
    • Would this effect occur?
    • Is this the correct root cause?
    • Are these controls applicable?
    • Should any of the three ratings be changed?

Pitfall 17 | Assuming Detection Controls Are Better Than They Are

  • Some controls are not as good as they are perceived to be:
  • High repeatability and reproducibility.
  • Don’t test for what we think they test for.
  • Only test part of the product.

Pitfall 18 | Assuming Detection Controls Apply When They Don’t

  • A control might apply to one effect of a failure mode but not another.
  • For example, final inspection is a control against a defect impacting a customer, but it may not be a control against rework or scrap.

Pitfall 19 | Not Linking with Mistake-Proofing

  • FMEA is a prioritization tool. It doesn’t eliminate failure modes or effects by itself.
  • Companies need to apply tools such as mistake-proofing to eliminate the root causes of failure modes.
  • This is especially true with failure modes that have very severe effects.

Pitfall 20 | Not Tying into Control Plans

  • The control plan tells people how to react when a failure mode occurs.
  • The FMEA will not be a living document if it is not tied to the control plan.

Pitfall 21 | Failing to Update the FMEA

  • As new potential failure modes are identified, they should be added to the FMEA and control plans developed for them.
  • It is critical that the template also be updated.