How to create an organization and implement FMEA on shop-floor

1. Subikash Roy –
Director Process Operations – Asia Pacific
Schaeffler Holding (China) Co. Ltd.

2. Using FMEA Intelligently – Techniques to Review PFMEA on Shopfloor Page 1

3. Objectives, Purpose and Scope of a PFMEA
Purpose • To predict failure modes
• To analyze effects of failures
• To build in safety and quality into the process
• To continuously improve robustness of processes
Scope • Ultimate user
• External customer
• Internal customer
• Society and Environment
Measurement • Severity
• Occurrence
• Detection
• RPN
• Customer & Supplier Rejections
• High Inprocess Rejections
Target • Zero Defects
• Safety and Quality to customers
Deployment Process • Deployment of shopfloor data to adjust Occurrence and Detection
Framework • Review mechanisms and methods for PFMEA updating
•Focus • Prediction of variations in shopfloor process
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4. Inputs to Process FMEA
 Process Flow Diagram
 Analyze flow of Process
 Team knowledge of manufacturing/ assembly process required
 Identify the incoming sources of variation
 Identify the desired outcomes
 What is the process supposed to do?
 What is its purpose
 What is its function?
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5. PFMEA Special Characteristics
PFMEA SPECIAL CHARACTERISTICS TABLE
FMEA Type Classification To Indicate Criteria Actions Required
Product Effect Assembly Effect
Customer/
Process
 Critical
Characteristic
Severity = 9, 10 Special Control
Required*
Process SC Significant Severity = 5-8, Special Control
Characteristic Occurrence = 4-10 Required*
Manufacturing/
Process HI High Impact Severity = 4-7 Emphasis**
Characteristic Occurrence = 4-10
Process OS Operator Safety Severity = 9, 10 Safety Sign-off
Process
 Special
requirements
As required by
Customer
As required by
Customer
* Included in Control Plan
** Included in Q-Alerts, Special WI etc.
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6. Process Function Requirements
 In Process FMEAs, functions have the following 2 components:
 Process characteristics or process requirements. These include operating
conditions and process parameters like job rates and production
maintenance requirements.
 Product specification requirements for the operations including the item
dimensions and all associated engineering requirements (i.e., engineering
spec., performance spec.)
– Example: Operation #20: Drill hole size X mm, through depth Y mm
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7. How to Identify Potential Failure Modes?
Type of Failure Categories of
How to Identify Failure Mode What to Check
Mode Failure Mode
• Why would the item be rejected at System Appropriate & Valid Std.
No Function
this process operation?
• How would the item not conform to Partial
specification at this process Manufacturing Dimension, Surface Finish
Function
operation? Relational, Part
• What would the next operator or Over Function Assembly Missing, Misaligned, Disori
subsequent operators consider ented
unacceptable? Time Degraded Receiving
Receiving Inspection
• What would the ultimate customer Function Inspection
find unacceptable?
• Is there a possibility to fail Unintended Testing/
Testing/ Inspection
regulatory compliance? Function Inspection
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8. Causes and Effects of Failures
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9. Severity Ratings – Changed only through change in product or process design
Criteria: Severity of Effect
This ranking results when a potential failure mode results in a final customer and/or a
Effect manufacturing/assembly plant defect. The final customer should always be considered first. If Ranking
both occur, use the higher of the two severities.
Criteria: Severity of Effect Defined
Hazardous Or may endanger operator (machine or assembly) without warning. High Accidents on
10
without warning machine/ operator.
Hazardous with
Or may endanger operator (machine or assembly) with warning. 9
warning
Or 100% of product may have to be scrapped, or vehicle/item repaired in repair department
Very High 8
with a repair time greater than one hour.
Or product may have to be sorted and a portion (less than 100%) scrapped, or vehicle/item
High 7
repaired in repair department with a repair time between a half-hour and an hour.
Or a portion (less than 100%) of the product may have to be scrapped with no sorting, or
Moderate 6
vehicle/item repaired in repair department with a repair time less than a half-hour.
Or 100% of product may have to be reworked, or vehicle/item repaired off-line but does not go
Low 5
to repair department.
Very Low Or the product may have to be sorted, with no scrap, and a portion (less than 100%) reworked. 4
Or a portion (less than 100%) of the product may have to be reworked, with no scrap, on-line
Minor 3
but out-of-station.
Or a portion (less than 100%) of the product may have to be reworked, with no scrap, on-line
Very Minor 2
but in-station.
None Or slight inconvenience to operation or operator, or no effect. 1
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10. Process Controls
 Points to consider
 To increase probability of Detection, process and/ or design revisions
are required.
 Generally, improving Detection controls is costly & ineffective for
quality improvements.
 Increasing quality control or inspection frequency is not a positive
corrective action and should be utilized only as a temporary measure.
 In some cases, a design change to a specific part may be required to
assist in Detection.
 Changes to current control system may be implemented to increase
probability of Detection.
 Emphasis must be on preventing defects (i.e., reducing Occurrence)
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11. Using FMEA Intelligently – Techniques to Review PFMEA on Shopfloor Page 10

12. Triggering the PFMEA
Man Machine Material Method Measurement Management
• Skill Change • Low MTBF, High • Not conform to • Process Change • Faulty measurement •Takt Time change
• New Operator MTTR spec. • Six Sigma Projects equipment (Self & supplier) • Non-std. activities
• Not trained • High Rejections • Supplier process • Value Stream • Infrequent calibration • Not conform no.
Senior & Middle Management
sufficiently after • High quality variation change •High & recurring in-process of jobs per hour
method change variation • Inconsistent tool • Kaizen project rejections • Cycle time higher
• Operating new • New machine wear • Bypass Poka Yoke/ • High supplier rejections than planned
machine • New product on • New substituted Safety • High & recurring customer • FMEA Review
STRATEGY
• New product in machine material • Supplier Method complaints System
CHECK
production change • Tool capability low • Supplier change
OCCURRENCE RATING ADJUST
• In-process Rejections Trend - <If continuously increasing for >1 week>
• Customer complaints Trend - <If continuously increasing for > 1 week>
ACT
DETECTION RATING ADJUST
• High frequency of problem being detected outside process (Detection Probability = Pieces detected outside
process/ Total pieces produced) <Includes Internal & External Customers>
Lower Mgmt. & Operator.
• No. of customer complaints related to FMEA Failure Modes
EXECUTION
• Sort out Issues by Priority (5s of Mind and Action)
• Prepare timing plan for each issue
PLAN
• Monitoring system including coaching and mentoring of employees where required
• Recurrence and Sustenance criteria
• Verify actual Data from Shopfloor Check
• Observe in Gemba for issues (include Mura and Muri also)
DO
• Use appropriate QC tools for arriving at Root Cause of the problem Do Act
• Check and verify solution for recurrence and sustenance
• Check for convenience of operation to operator Plan
• Communication solution to Higher Management
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13. Occurrence Ratings From Actual Process Performance
Possible Failure
Probability of Failure Cpk Ranking
Rates
1 in 2 < 0.33 10
Very High: Failure is almost inevitable
1 in 3 ≥ 0.33 9
High: Generally associated with processes similar to 1 in 8 ≥ 0.51 8
previous processes that have often failed 1 in 20 ≥ 0.67 7
Moderate: Generally associated with processes 1 in 80 ≥ 0.83 6
similar to previous processes which have 1 in 400 ≥ 1.00 5
experienced occasional failures, but not in major
proportions 1 in 2,000 ≥ 1.17 4
Low: Isolated failures associated with similar
1 in 15,000 ≥ 1.33 3
processes
Very Low: Only isolated failures associated with
1 in 150,000 ≥ 1.5 2
almost identical processes
Remote: Failure is unlikely. No failures ever
1 in 1,500,000 ≥ 1.67 1
associated with almost identical processes
Above Figures are only indicative samples
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14. Detection Ratings from Actual Process Performance
Criteria: Likelihood the existence of a defect will be
Detection detected before product advances to next or subsequent Ranking
process or to customer
Almost
Detection Probability < 80 % 10
Impossible
Very Remote Detection Probability 80 % 9
Remote Detection Probability 82.5 % of failures 8
Very Low Detection Probability 85 % of failures 7
Low Detection Probability 87.5 % of failures 6
Moderate Detection Probability 90 % of failures 5
Moderately High Detection Probability 92.5 % of failures 4
High Detection Probability 95 % of failures 3
Very High Detection Probability 97.5 % of failures 2
Almost Certain Detection Probability 99.5 % of failures 1
Above Figures are only indicative samples
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15. Suggested Detection Methods based on Ranking
Detection Criteria Suggested Range of Detecting Methods Ranking
Error Proof
Inspection
Gauging
Manual
Almost Absolute certainty of non- Cannot detect or is not checked 10
Impossible detection
Improve Process
Very Remote Controls will probably not Control is achieved by indirect or random checks only 9
Robustness
detect
Remote Controls have very poor Control is achieved with visual inspection only 8
chance of detection
Very Low Controls have poor chance Control is achieved with double visual inspection only 7
of detection
Low Controls may detect Control is achieved by SPC 6
Moderate Control may detect Control is based on variable post process gauging. OR Go/NoGo 5
gauging performed on 100% of parts post process.
Moderately Controls have a good Error detection in subsequent operations OR gauging performed 4
High chance to detect in setup and first piece check.
High Controls have a very good Error detection in-process OR in subsequent process by multiple 3
chance to detect layers of acceptance. Cannot pass discrepant part.
Very High Controls almost certain to Error detection in-process by automatic gauging with stop 2
detect feature. Cannot accept discrepant part.
Extremely Controls certain to detect Discrepant parts cannot be made because item has been error 1
High proofed by DFMEA
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16. Re-rating RPN After Actions Have Occurred
– Severity typically stays the same. This can only be changed
through product/ process redesign
– 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!!!
 100% inspection is only 80% effective!
 Reducing RPN with detection does not eliminate failure mode, or
reduce probability of causes
 Detection of 10 is not bad if occurrence is 1
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