FMEA Pitfalls and Limitations
Pitfall 1: Prioritizes, Doesnít Correct
- The initial output of an
FMEA is the prioritizing of failure modes based on their risk
- This alone does not eliminate the failure mode.
Additional action that might be outside the FMEA is needed.
2 Only as Good as the Team
- Identifying failure modes is a team
- 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 should be meaningful to everyone in
- The generic rating scales might be confusing to
- 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
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
- 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 also bring an outside perspective to the team.
- Might be able to tie your process in with theirs.
Becoming a Full-Time Job
- Sometimes people use an FMEA as an excuse
to get out of doing their regular job.
- You canít afford to have
people who are just conducting FMEAs.
- Wonít get their regular work
- Even if FMEAs are made their ďregularĒ 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
Pitfall 13 Not Getting into the Details
- A superficial
look at the process will miss many failure modes.
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.
Confusing Root Cause and Failure Mode
- Teams often have root causes
as failure modes.
- A failure mode is the failure to perform the
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.
test for what we think they test for.
- Only test part of the
Pitfall 18 Assuming Detection Controls Apply When They
- A control might apply to one effect of a failure mode but
- 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
is a prioritization tool. It doesnít 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
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