Entrenamiento metodología PFMEA

1. PFMEA Training for Industry
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2. PFMEA
PFMEA analyzes Process risk – any type
of process
We anticipate Failure Modes – how
could the process fail?
What would the Effects of these
failures be, and what action
should we take?

3. PFMEA is a risk assessment tool that calculates a Risk Priority
Number (RPN) to prioritize risk levels
The Risk Calculation
RPN = Severity x Occurrence x Detection

4. PFMEA: RPN Value
RPN = S x O x D
SEVERITY
OCCURENCE
DETECTION
SEVERITY OF A GIVEN FAILURE MODE
1 = INSIGNIFICANT 10 = LIFE THREATENING
HOW OFTEN THE FAILURE IS LIKELY TO OCCUR
1 = INSIGNIFICANT 10 = REGULARLY
LIKELIHOOD THAT CURRENT CONTROLS WILL DETECT
1 = GUARANTEED 10 = NO DETECTION

5. Common Risk Rankings
SEVERITY OCCURENCE DETECTION
RANK
1
3
2
5
4
7
6
8
9
10
None
Hazardous, without
warning
Hazardous, with
warning
Very high
High
Moderate
Low
> 100 per 1,000
Certain
Very low
Minor
Very minor
50 per 1,000
20 per 1,000
10 per 1,000
5 per 1,000
2 per 1,000
1 per 1,000
.5 per 1,000
> .01 per 1,000
.1 per 1,000 Almost certain
High
Moderately High
Moderate
Moderately high
High
Absolutely impossible
Very remote
Remote

6. High RPN Example
Process Step: Screw the ground wire to the chassis
Potential Failure Mode: Screw not tightened to specified torque
Effect: Shock hazard if screw backs out over time
Loose
Severity: 10 (hazardous without warning)
Occurrence: 7 (10 per 1,000) manual operation
Detection: 6 (low) random audit
RPN = 10 x 7 x 7 = 700: High Risk

7. High RPN Example – Same Severity, Better Control
Process Step: Screw the ground wire to the chassis
Potential Failure Mode: Screw not tightened to specified torque
Effect: Shock hazard if screw backs out over time
Loose
Severity: 10 (hazardous without warning)
Occurrence: 2 (.1 per 1,000)
- automatic screwdriver with torque control
Detection: 2 (almost certain)
- built-in torque feedback, line will stop if < limit
RPN = 10 x 2 x 2 = 40: Low Risk

8. Success Factors - Conducting a PFMEA
• Good facilitator
• Design, manufacturing
team members present
• Paper copies of S, O, D –
get agreement up front
on the rankings
• Also pass out copies of
the process flow diagram
“The biggest hang-up in PFMEA’s is
debating the S, O, and D values for a
given risk. When in doubt, go with
higher-risk values and move on to the
next risk.”

9. Completing the PFMEA Template

10. Process Function, Failure Modes, Effect
Follow the process flowchart and
note each process step. A single
process step can have multiple rows
associated with it.
For each process step there can be
zero to any number of potential
failure modes. Note each failure
mode that the team is aware of.
For each potential failure mode, note
the effect of the failure, both on the
customer and inside the
manufacturing facility (if applicable).
The failure effect will determine the
severity score.
1
2
3

11. Severity, Potential Causes, and Occurrence Score
Note the severity of the
effect, using pre-determined
guidelines.
Note the causes of failure,
and the associated likelihood
of occurrence, also a 1-10
scale using pre-determined
guidelines.
4

12. Detection Score and RPN Calculation
Assign a detection score on a 1-
10 scale, then the spreadsheet
will do the math and update the
Risk Priority Number (RPN).
If the RPN is too high, discuss
countermeasures.
5

13. Actions Take and Updated RPN Score
Based on the
recommended actions, note
which actions were
implemented, along with the
updated Severity,
Occurrence, and Detection
values.
6

14. Wrap-Up – Measuring the Quality of a PFMEA
1. The team has done something about the high RPN’s: countermeasures
and updated RPN values are documented.
2. The steps in the PFMEA are matched up with a detailed process flow
diagram.
3. A control plan exists that mirrors the process controls referenced in the
PFMEA.