Resource file for ‘Lean Six Sigma Dual Certification:
White and Yellow Belt’
Section: Yellow Belt (Improve Phase)
Instructor: Gunjan Subedi
Terms used in FMEA analysis
Severity (S):
The seriousness of the failure consequences is termed as Severity. On a scale the of 1 to 10, the
effects with low severity is given lesser scores and the effects with higher severity is given higher
score.
Score Severity Guidelines
Level of Severity Six Sigma
Failure to Meet Safety and/or Regulatory
Requirements: May endanger operator
10 (machine or assembly) without warning. Injure a customer or employee
Failure to Meet Safety and/or Regulatory
Requirements: May endanger operator
9 (machine or assembly) with warning. Be illegal
Major Disruption: 100% of product may have
8 to be scrapped. Line shutdown or stop ship. Render product or service unfit for use
Significant Disruption: A portion of the
production run may have to be scrapped.
Deviation from primary process including
7 decreased line speed or added manpower. Cause extreme customer dissatisfaction
Moderate Disruption: 100% of production
run may have to be reworked off line and
6 accepted. Result in partial malfunction
Moderate Disruption: A portion of the
production run may have to be reworked off Cause a loss of performance which is likely to result in
5 line and accepted. a complaint
Moderate Disruption: 100% of production
run may have to be reworked in station before
4 it is processed. Cause minor performance loss
Moderate Disruption: A portion of the
production run may have to be reworked in Cause a minor nuisance but can be overcome with no
3 station before it is processed. performance loss
Minor Disruption: Slight inconvenience to Be unnoticed and have only minor effect on
2 process, operation, or operator. performance
1 No Effect: No discernible effect. Be unnoticed and not affect the performance
Table 1: Severity Guideline. Source: Automotive Industry Action Group AIAG (PFMEA 4th ed.)
Resource file for ‘Lean Six Sigma Dual Certification:
White and Yellow Belt’
Section: Yellow Belt (Improve Phase)
Instructor: Gunjan Subedi
Occurrence (O) : There may be many kinds of failure causes which should be identified properly and
documented. The causes which occurs or repeats more is more dangerous and needs to be handled
first than the failure cause with low chances of occurrence. On a scale of 1 to 10, higher score
indicates high occurrence which should be given more focus to solve than a lower score value.
Score Occurrence Guidelines
Level of Occurrence Six Sigma
10 Very High: ≥ 100 per thousand; ≥ 1 in 10 More than once per day > 30%
9 High: 50 per thousand; 1 in 20 Once every 3-4 days < 30%
8 High: 20 per thousand; 1 in 50 Once every week < 5%
7 High: 10 per thousand; 1 in 100 Once per month < 1%
6 Moderate: 2 per thousand; 1 in 500 Once every 3 months < 0.03%
5 Moderate: 0.5 per thousand; 1 in 2,000 Once every 6 months < 1 per 10,000
4 Moderate: 0.1 per thousand; 1 in 10,000 Once per year < 6 per 100,000
3 Low: 0.01 per thousand; 1 in 100,000 Once every 1-3 years < 6 per million
< 3 per 10
2 Low: ≤ 0.001 per thousand; 1 in 1,000,000 Once every 3-6 years million
1 Very Low: Failure is eliminated through preventive control. Once every 6-100 years < 2 per billion
Table 2: Occurrence Guideline. Source: Automotive Industry Action Group AIAG (PFMEA 4th ed.)
Resource file for ‘Lean Six Sigma Dual Certification:
White and Yellow Belt’
Section: Yellow Belt (Improve Phase)
Instructor: Gunjan Subedi
Detection (D):
Detection indicates how easy or hard the quality assurance or quality inspectors can detect the
causes of failure. On a scale of 1 to 10, 10 indicates a situation very difficult to detect whereas
subsequent lower values indicate higher chances of detection.
Score Detection Guidelines
Level of detection Six Sigma
Almost Impossible. No detection opportunity: No current
10 process control; cannot detect or is not analysed. Defect caused by failure is not detectable
Very Remote. Not likely to detect at any stage: Failure
Mode and/or Error (Cause) is not easily detected (e.g.,
9 random audits). Occasional units are checked for defects
Remote. Problem Detection Post Processing: Failure
Mode detection post-processing by operator through
8 visual/tactile/audible means. Units are systematically sampled and inspected
Very Low. Problem Detection at Source: Failure Mode
detection in-station by operator through
visual/tactile/audible means or post-processing through
use of attribute gauging (go/no-go, manual torque
7 check/clicker wrench, etc.). All units are manually inspected
Low. Problem Detection Post Processing: Failure Mode
detection post-processing by operator through use of
variable gauging or in-station by operator through use of
attribute gauging (go/no-go, manual torque check/clicker
6 wrench, etc.). Manual inspection with mistake-proofing modifications
Moderate. Problem Detection at Source: Failure Mode or
Error (Cause) detection in-station by operator through use
of variable gauging or by automated controls in-station
that will detect discrepant part and notify operator (light,
buzzer, etc.). Gauging performed on setup and first-piece
5 check (for set-up causes only). Process is monitored (SPC) and manually inspected
Moderately High. Problem Detection Post Processing:
Failure Mode detection post-processing by automated
controls that will detect discrepant part and lock part to SPC is used with an immediate reaction to out of
4 prevent further processing. control conditions
High. Problem Detection at Source: Failure Mode
detection in-station by automated controls that will detect
discrepant part and automatically lock part in station to SPC as above, 100% inspection surrounding out of
3 prevent further processing. control conditions
Very High. Error Detection and/or Problem Prevention:
Error (Cause) detection in-station by automated controls
that will detect error and prevent discrepant part from
2 being made. All units are automatically inspected
Resource file for ‘Lean Six Sigma Dual Certification:
White and Yellow Belt’
Section: Yellow Belt (Improve Phase)
Instructor: Gunjan Subedi
Almost Certain. Detection not applicable; Error
Prevention: Error (Cause) prevention as a result of fixture
design, machine design or part design. Discrepant parts
cannot be made because item has been error-proofed by Defect is obvious and can be kept from affecting the
1 process/product design. customer
Table 3: Detection Guideline. Source: Automotive Industry Action Group AIAG (PFMEA 4th ed.)
