Process F.M.E.A

Process Failure Mode & Effect Analysis (PFMEA)

Uniparts India Limited By: Pankaj Nalwa


“Our product or process is established, it doesn’t have any failure modes.”

Every product or process has modes of failure, which can arise even
though your product or process is established and you are producing or
performing it for years.



“FMEA takes lot of time and resources, also it does not provide any benefit. It
can be done by one person instead.”

FMEA do take time and people resources as it is a team based activity.
Effective FMEAs cannot be done by one person sitting alone and filling
out FMEA forms.

FMEA do not require complicated statistics, still it can yield significant
savings for organization by reducing cost liabilities due to process or
product that does not performed as required.



Current Paradigm
FMEA

-Taken lightly
… “Selective” products / processes chosen.
… Based on opinion.
… All “magically” below the RPN cut-off.
-Too late
… Error / Mistake proofing window long gone.
… Rarely validated with field results.
“Paper exercise done when pushed”


New Paradigm
FMEA

Error / Mistake Process Control Maintenance
Proofing Plans Plans

-Taken Seriously
… All critical and new products / processes.
… Data driven.
… Roll-up RPN values.
-Early
… Completed while design is still fluid.
… “Living” document.
“Ensures our products and processes are
robust”


The objective of a FMEA is to look for all of the ways a process or
product can fail.

A product failure occurs when the product does not function as it
should or when it malfunctions in some way.

Failures are not limited to problems with the product. Because
failures also can occur when the user makes a mistake, those types
of failures should also be included in the FMEA.

Anything that can be done to ensure the product works correctly,
regardless of how the user operates it, will move the product closer
to 100% total customer satisfaction.



Process FMEA is an effort to prevent failures (due to process)
before they happen, to assess the risk associated with those failure
modes, to rank the issues in terms of importance and to identify and
carry out corrective actions to address the serious concerns.

Process FMEAs uncover process problems related to the manufacture of
the product.
It is helpful when conducting a process FMEA to think in terms of the five
elements of a process: People, Materials, Equipment, Methods and
Environment. With these five elements in mind, ask: How can process
failure affect the product, processing efficiency or safety?



FMEA Core Team

It is helpful to have people in team who have different levels of familiarity
with the product or process.

Those who are most familiar with it will have valuable insights, but may
overlook some of the most obvious potential problems. Those who are less
familiar with the process or product will bring unbiased, objective ideas into
the FMEA process.

A point is often debated with FMEAs is what role the process expert plays
on the FMEA team. A person with expertise in the process can bring
tremendous insight to the team and can help speed the process.



Ten Steps for an Process FMEA

1) Review the process.
2) Brainstorm potential failure modes.
3) List potential effects of each failure mode.
4) Assign a Severity ranking for each effect.
5) Assign an Occurrence ranking for each failure mode.
6) Assign a Detection ranking for each failure mode and /or effect.
7) Calculate the Risk Priority Number for each effect.
8) Prioritize the failure modes for action.
9) Take action to eliminate or reduce the high-risk failure modes.
10) Calculate the resulting RPN as the failure modes are reduced or
eliminated.



Ways in which a product or process can fail are called FAILURE
MODES.

Each failure modes has a potential effect, and some effects are more
likely to occur than others. In addition, each potential effect has a
relative risk associated with it.

The FMEA process is a way to identify the failures, effects, and risks
within a process or product, and then eliminating or reduce them.



Evaluating the Risk of Failure

The relative risk of a failure and its effects is determined by three
factors:

 Severity – The consequence of the failure should it occur.

 Occurrence – The probability or frequency of the failure occurring.

 Detection – The probability of the failure being detected before the
impact of the effect is realized.



Using the data and knowledge of the process or product, each potential
failure mode and effect is rated in each of these three factors on a scale
ranging from 1 to 10, low to high.

By multiplying the ranking for the three factors (Severity x Occurrence x
Detection), a risk priority number (RPN) will be determined for each potential
failure mode and effect.

The risk priority number (which will range from 1 to 1,000 for each failure
mode) is used to rank the need for corrective actions to eliminate or reduce
the potential failure modes.

Once corrective action has been taken, a new RPN for the failure is
determined by reevaluating the Severity, Occurrence and Detection
rankings. This new RPN is called “Resulting RPN”.

Improvement and corrective action must continue until the resulting RPN is
at acceptable level for all potential failure modes.



For High Severity 9/10



Current or
Customer Process
Expected Process Implementation
Design Flow
quality Changes and verification
Requirements Diagram
performance

Recommended
Corrective actions
Process FMEA document i.e.
Error proofing

Process Continuous Improvement Efforts
Control And RPN reduction loop
Plan

Operator Communication of standard
Job
of work to operators
Instructions


Criteria: Severity of Effect
These rankings results when a potential failure mode results in a final
customer and/or a manufacturing/assembly plant defect.
Effect The final customer should always be considered first. Ranking Remarks
If both occur, use the higher of two severities.

Customer Effect Manufacturing / Assembly Effect

Hazardous without
warning
Very high severity ranking when a
potential failure mode affects safe
Or may endanger operator
(Machine or assembly) without
10 Critical
characteristic
vehicle operation and/or involves warning.
noncompliance with government
regulation without warning.
Hazardous with
warning
Very high severity ranking when a
potential failure mode affects safe
Or may
(Machine
endanger
or
operator
assembly) with
9 Critical
characteristic
vehicle operation and/or involves warning.
noncompliance with government
regulation with warning.
Very High Vehicle / item inoperable (loss of
primary function)
Or 100% of product may have to be
scrapped, or vehicle / item repaired
8 Major
characteristic
in repair shop with repair time
greater than one hour.
High Vehicle / item operable but at a
reduced level of performance.
Or product may have to be sorted
and a portion (less than 100%)
7
Customer very dissatisfied. scrapped, or vehicle / item repaired
in repair department with a repair
time between ½ hr and an hour.
Moderate Vehicle/item operable but comfort /
convenience item(s) inoperable.
Or a portion (less than 100%) of the
product may have to be scrapped
6
Customer dissatisfied. with no sorting, or vehicle / item
repaired in repair shop with a repair
time of less than ½ hr.



Criteria: Severity of Effect
These rankings results when a potential failure mode results in a final
customer and/or a manufacturing/assembly plant defect.
Effect The final customer should always be considered first. Ranking Remarks
If both occur, use the higher of two severities.

Customer Effect Manufacturing / Assembly Effect

Low Vehicle / item operable but comfort /
convenience item(s) operable at a
Or 100% of product may have to be
reworked, or vehicle / item repaired
5
reduced level of performance. off-line but does not go to repair
department.
Very Low Fit and Finish / Squeak and Rattle
item does not conform. Defect
Or the product may have to be
sorted, with no scrap, and a portion
4
noticed by most customers (greater (less than 100%) reworked.
than 75%).
Minor Fit and Finish / Squeak and Rattle
product may have to be reworked,
3
noticed by 50% of customer. with no scrap, on-line but out-of-
station.
Very Minor Fit and Finish / Squeak and Rattle
product may have to be reworked,
2
noticed by discriminating customers with no scrap, on-line but in-station.
(less than 25%).
None No discernible effect. Or slight inconvenience to operation
or operator, or no effect.
1



Suggested P.F.M.E.A Occurrence Evaluation Criteria.
Probability Likely Failure Rates Ranking Remarks
Very High: Persistent Failures ≥ 100 per thousand pieces 10
50 per thousand pieces 9
High: Frequent Failures 20 per thousand pieces 8
Moderate: Occasional
Failures
Low: Relatively Few Failures 0.5 per thousand pieces 3
0.1 per thousand pieces 2
Remote: Failure is unlikely ≤ 0.01 per thousand pieces 1


Inspectio
Detection Criteria n Types Suggested Range of Detection Methods Ranking
A B C
Almost Absolute certainty of non- Cannot detect or is not checked.
Impossible detection 10
Very Control will probably not detect Control is achieved with indirect or random checks only.
Remote 9
Remote Controls have poor chance of Control is achieve with visual inspection only.
detection 8
Very Low Control have poor chance of Control is achieve with double inspection only.
detection 7
Low Controls may detect Controls is achieved by charting methods, such as Statistical
Process Control. 6
Moderate Controls may detect Control is based on variable gauging after parts have left the
station, or GO/NO-GO gauging performed on 100% of the parts 5
after parts have left the station.
Moderately Controls have a good chance to Error detection in subsequent operations, Or gauging
High detect performed on set up and first-piece check (for set up causes 4
only).
High Controls have a good chance to Error detection in-station, Or error detection in subsequent
detect operations by multiple layers of acceptance: supply, select, 3
install, verify. Cannot accept discrepant part.
Very High Controls almost certain to detect Error detection in-station (automatic gauging with automatic
stop feature). Cannot pass discrepant part. 2
Certain Controls certain to detect Discrepant parts cannot be made because item has been error-
proofed by process/product design. 1



10
Confirmed Critical Characteristic
9
S 8
e 7 Confirmed Significant
v
Characteristic; Action Required
e 6
r 5
i
4 Annoyance
t
y 3 Zone
2
1
1 2 3 4 5 6 7 8 9 10
Occurrence


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