2. Origin
Failure mode and effect analysis (FMEA) was one
of the first systematic techniques for failure analysis.
It was developed by reliability engineers in the 1950s
to study problems that might arise from malfunctions
of military systems
3. Most COMMON Types of FMEA's
Design (Potential) Failure Modes and
Effects Analysis-DFMEA
• Focus is on potential design- related failures
and their causes.
!
Process (Potential) Failures Modes and
Effects Analysis-PFMEA
• Focuses is on potential process failures and
their causes.
4. PFMEA's
!
● Focus is on potential process –related
failures and their causes.
▪Main drive is to understand the process through the
identification of as many potential failures as possible.
o e.g. Incorrect material used
● PFMEA typically assumes that the design
is sound.
● Development of Recommended Actions is
targeted at eliminating the Root Cause of
the potential failures.
5. PFMEA's benefits
•Identifies Process Functions
and Req’s!
•Identifies potential failure
modes!
•Assesses effect of failure!
•Identifies causes of failures!
•Identifies process controls!
•Identifies confirmed Critical
Characteristics!
•Provides an objective base for
action
6. PFMEA's - who
prepares it
•A team effort - including!
•Manufacturing/production!
•Engineering!
•Design !
•Quality!
•Test!
!
•However it is a moving feast
7. PFMEA
Three Parts:
● Process Flow Diagram (PFD)
● Process Failure Mode and Effects
Analysis (PFMEA)
● Process Control Plan (PCP)
13. PFD Feeds PFMEA
Identify the Function(s)
● Function is a description of what the
Process does to meet the requirements
➢Related to process specification and product
characteristics
➢Comes from the PFD operation description column
● Functions can be described as:
➢Do this operation…
➢To this part or material…
➢With this tooling or equipment…
28. Current Controls
2 types of controls
Prevention
Prevent the Cause/mechanism or failure mode/effect from
occurring or reduce their rate of occurrence
!
Detection
Detect the cause/mechanism and lead to corrective action
34. Analysis Of Risk
▪ RPN / RISK PRIORITY NUMBER
▪ What Is Risk?
▪ Probability of danger
▪ Severity/Occurrence/Cause
35. Evaluation by RPN Only
▪ Case 1
o S=5 O=5 D=2 RPN = 50
▪ Case 2
o S=3 O=3 D=6 RPN = 54
▪ Case 3
o S=2 O=10, D=10 = 200
▪ Case 4
o S=9 O=2 D=3 = 54
WHICH ONE
IS WORSE?
36. Example
▪ Extreme Safety/Regulatory Risk
o =9 & 10 Severity
▪ High Risk to Customer Satisfaction
o Sev. > or = to 5 and Occ > or = 4
▪ Consider Detection only as a measure of Test
Capability.
40. Re-rating RPN After Actions Have
Occurred
▪ Severity typically stays the same.
▪ Occurrence is the primary item to reduce / focus on.
▪ Detection is reduced only as a last resort.
▪ Do not plan to REDUCE RPN with detection actions!!!
o 100% inspection is only 80% effective!
o Reducing RPN with detection does not eliminate failure mode,
or reduce probability of causes
o Detection of 10 is not bad if occurrence is 1