[PPT]The Quality Improvement Model - Purdue Universitykuczek/stat513/SPC Course Slides/7... · Web...
Transcript of [PPT]The Quality Improvement Model - Purdue Universitykuczek/stat513/SPC Course Slides/7... · Web...
7-1
Investigate & Fix Special Causes
TheQualityImprovementModel
Use SPC to Maintain Current Process
Collect & Interpret
Data
Select Measures
Define Process
IsProcessCapable
?
Improve Process
Capability
IsProcessStable
?
Investigate & Fix Special Causes
No
Yes
No
Yes
Investigate & Fix Special Causes
Purpose:•Assure stability of the
measures.•Establish permanency of
solutions to recurring special causes.
•Improve procedures and training.
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Investigate & Fix Special Causes
Unstable Process
Time
Quality Characteristic
Control Chart
UCL
CL
LCL
How do we improve an unstable process?
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Investigate & Fix Special Causes
Potential Special Causes
Lack of standardization Lack of consistent process conditions
Uncontrolled process variables Unknown process variables Fluctuating business environment Equipment malfunctions
Unstable measurement process
Changes in process inputs
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Investigate & Fix Special Causes
The Improvement Process
Study the Symptoms Theorize Causes Establish True
Causes
Propose Alternative Solutions
Select & Apply Solution
Maintain Improvements
We must take the time to identify the cause before attempting to solve the problem.
Diagnose Solve
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Investigate & Fix Special Causes
Special Cause Action Plan(S.C.A.P.)
A planned sequence of activities for investigating and taking action on a problem which has been detected.
Provides a prioritized listing of potential special causes. The S.C.A.P. should be updated whenever necessary.
Actions1) Investigation2) Compensation 3) Documentation4) Correction5) Prevention
Note: This is the most important part in implementing S.P.C.
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Investigate & Fix Special Causes
Investigative Action
Systematic “detective” work to determine the root source of the special cause. The investigative actions should be directed toward determining:
What When Why Where
Unless the urgency of special cause dictates other action, investigative action should precede any other actions. Regardless of the urgency, investigative action should always be taken at some point.
Note: This is the most important part of the S.C.A.P..
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Investigate & Fix Special CausesCompensating Action
Adjustment made to the process after a nonconformity, defect, or other undesirable process situation in an attempt to restore the process to the desired state, without addressing the underlying cause of the situation. (ISO definition)
• Taking action on the process in the form of adjustments to the process. These actions do not remove the cause but are known to adjust the process in a favorable direction. (Adjusting)
OR• Taking action on the process to remove the symptom of the special cause. This may not prevent the same problem from recurring in the future. (Fixing)
Adjustments may help one part of the process but could be detrimental to others.
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Investigate & Fix Special Causes
DocumentationRecording the suspected cause of the problem, what actions were taken and how effective the action was.
Benefits:•
•
•
•
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Investigate & Fix Special Causes
Cause D
Cause G
CauseA
Cause B
Cause N All others
Frequency of Occurrence
Pareto of Causes
Note: Putting resources to eliminating Cause D will result in most significantImpact on process improvement.
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Investigate & Fix Special Causes
Corrective Action
Actions taken to eliminate the causes of existing nonconformity, defect, or other undesirable situation in order to prevent recurrence (ISO definition).
• Permanent removal of the root source of recurring special causes that have been identified.
Focus is on preventing major recurring special causes.
Implementation results in variability reduction.
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Investigate & Fix Special Causes
Preventive Action
Action taken to eliminate the causes of a potential nonconformity, defect, or other undesirable situation in order to prevent occurrence.(ISO definition)
• Permanent removal of the root source of a potential special cause that could affect the process.
May involve using learning's from one process on another process where the special cause might also occur.
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Investigate & Fix Special Causes
•A standard way to perform a task.
•A standard range that a key process variable should be within.
•Standards should be audited.
Control To A Standard
Note: S.O.P.'s NOT being followed can be a major reason for instabilities on control charts!
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Investigate & Fix Special Causes
• Control "Charts" will NOT improve the process!
•S.C.A.P's IMPROVE the process
•Provide a procedure for operations to follow in identifying and removing the special cause symptom.
• Promote a standardized approach to investigating and compensating for special causes.
• Provide a vehicle for documenting causes found and actions taken to aid in future problem solving.
Why S.C.A.P.'s?
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Investigate & Fix Special Causes
Rating of Importance to
Customer10 1 9 9 5 8
1 2 3 4 5 7
Bre
ak %
Mel
t Tem
p
Bot
tle O
utpu
t
Cla
rity
Wei
ght
Wal
l V
aria
tion
Total
Process Step Process Input
Melt Resin Resin 9 9 3 9 9 9 324Blow Bottle Mold Design 9 0 9 9 0 9 324
Extrude Parison Programing 3 3 9 0 9 9 231Extrude Parison Die Tip Temp 3 3 3 9 3 9 228
Blow Bottle Mold Water Temp 9 0 9 3 0 0 198
Blow BottleWater Volume/Cooling Rate
9 0 9 3 0 0 198
Extrude Parison Head Design 3 9 3 3 3 9 180Extrude Parison Tooling 3 3 3 3 3 9 174
Blow Bottle Pinch Design 9 0 9 0 0 0 171Melt Resin Barrell Temp 3 9 9 1 3 3 168Melt Resin Screw Speed 3 9 9 1 3 3 168Melt Resin Screw Design 3 9 9 1 1 1 142
Blow Bottle# of Mold Cooling Zones
9 0 3 0 0 0 117
Tail DetabTime from extraction to Detab
9 0 3 0 0 0 117
Remember The C&E Matrix
Note: C&E is a good place to start building control strategies. This information will be used to develop a Failure Modes Effect Analysis (FMEA) …
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Investigate & Fix Special Causes
Failure Modes and Effects AnalysisFailure Modes and Effects Analysis
A Tool for Developing SCAP's
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Investigate & Fix Special Causes
A structured approach to:A structured approach to: Assist in developing SCAP's identifying the ways in which a product or process
can fail estimating the risk associated with specific causes prioritizing the actions that should be taken to
reduce the risk evaluating the design validation plan (product) or
the current control plan (process)
Primary DirectivePrimary Directive:: Identify ways the product or process can fail and eliminate or reduce the risk of failure
FMEA Definition
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Investigate & Fix Special Causes
Vague Workmanship
Standards
Poor Control Plans & SOP’s
Raw Material Variation
Poorly Developed Specification
LimitsMeasurement Variation
(Online and QC)
Machine Reliability
Potential Safety
HazardsUnclear Customer Expectations
D. H. Stamatis, FMEA:FMEA from Theory to Practice, Quality Press, 1995
Poor Process Capability
Cumulative RiskCumulative Risk
Where Do Risks Come From?
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Key tool of process team to improve the process in a preemptivepreemptive manner (before failures occur)
Used to prioritizeprioritize resources to insure process improvement efforts are beneficial to customer
Used to documentdocument completion of projects
Should be a dynamicdynamic document, continually reviewed, amended, updated
Role of FMEA
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AnalyzesAnalyzes new processes
IdentifiesIdentifies deficiencies in the process control plan
EstablishesEstablishes the priority of actions
EvaluatesEvaluates the risk of process changes
IdentifiesIdentifies potential variables to consider in Exploratory Data Analyses (EDA) and Design of Experiments (DOE) studies
GuidesGuides the development of new processes
HelpsHelps set the stage for breakthrough
Purposes of FMEA
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Investigate & Fix Special CausesFMEA Inputs and Outputs
InputsInputs Process map C&E matrix Process history Process technical procedures
OutputsOutputs List of actions to prevent causes or to detect
failure modes History of actions taken
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Investigate & Fix Special CausesFMEA Team
Team approach is necessary
Recommended representatives: Design Practitioners / Operators / Supervisors Quality Reliability Maintenance Materials Testing Supplier
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Investigate & Fix Special Causes
Failure Mode
Effect
Cause
Current Controls
Severity, Occurrence, Detection
Risk Priority Number (RPN)
FMEA Terms
Next, Going to define each of these terms…
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Investigate & Fix Special CausesFMEA Exercise
Input Failure Mode Effects Causes Controls
As we go through the different definitions and terms, complete the form below for your process
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Investigate & Fix Special CausesFailure Mode - Definition
Failure ModeFailure Mode - the way in which a specific process input fails - if not detected and either corrected or removed, will cause the effect to occur
Can be associated with a defect (in discrete manufacturing) or a process input variable that goes outside of specification
o Anything that an operator can see that’s wrong is considered a failure mode
ExamplesExampleso Incorrect PO numbero Sample Size too smallo Dropped call (customer service)o Temperature too higho Surface contaminationo Paint too thin
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Investigate & Fix Special CausesEffect - Definition
EffectEffect - impact on customer requirements Generally external customer focus, but can also include
downstream processes
ExamplesExamples Incorrect PO number: Accounts receivable traceability
errors Dropped call: Customer dissatisfaction Temperature too high: Paint cracks Surface contamination: Poor adhesion Paint too thin: Poor coverage
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Investigate & Fix Special CausesCause - Definition
CauseCause Sources of process variation that causes the failure mode to
occur Identification of causes should start with failure modes
associated with the highest severity ratings
ExamplesExamples Incorrect PO number: Typographical error Dropped call: Insufficient number of CS representatives Temperature too high: Thermocouple out of calibration Surface contamination: Overhead hoist systems Paint too thin: High solvent content
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Investigate & Fix Special CausesCurrent Controls - Definition
Current ControlsCurrent Controls Systematized methods/devices in place to prevent or
detect failure modes or causes (before causing effects)
Prevention consists of mistake proofing, automated control and set-up verifications
Controls consist of audits, checklists, inspection, laboratory testing, training, SOP’s, preventive maintenance, etc.
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Investigate & Fix Special Causes
Failure Mode 1
Failure Mode 2Effect 1
Note that the relationship between the failure mode and the effect is not always 1-to-1
Effect 1
Effect 2Failure Mode 1
Linking Failure Modes to Effects
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Investigate & Fix Special CausesRisk Priority Number (RPN)
The output of an FMEA is the Risk Priority Number The RPN is a calculated number based on
information you provide regarding o the potential failure modes, o the effects, and o the current ability of the process to detect the
failures before reaching the customer It is calculated as the product of three quantitative
ratings, each one related to the effects, causes, and controls:
Effects Causes ControlsRPN = Severity X Occurrence X Detection
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Investigate & Fix Special CausesDefinition of RPN Terms
Severity (of Effect)-Severity (of Effect)- importance of effect on customer requirements - could also be concerned with safety and other risks if failure occurs (1=Not Severe, 10=Very Severe)
Occurrence (of Cause)-Occurrence (of Cause)- frequency with which a given cause occurs and creates a failure mode. Can sometimes refer to the frequency of a failure mode (1=Not Likely, 10=Very Likely)
Detection (capability of Current Controls) -Detection (capability of Current Controls) - ability of current control scheme to detect or prevent: the causes before creating failure mode the failure modes before causing effect 1=Likely to Detect, 10=Not Likely at all to Detect
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Investigate & Fix Special Causes"Example" Rating Scale
Rating Severity of Effect Likelihood of Occurrence Ability to Detect
10 Hazardous without warningVery high:
Can not detect
9 Hazardous with warningFailure is almost inevitable
Very remote chance of detection
8 Loss of primary functionHigh:
Remote chance of detection
7Reduced primary function
performanceRepeated failures
Very low chance of detection
6 Loss of secondary functionModerate:
Low chance of detection
5Reduced secondary function
performanceOccasional failures
Moderate chance of detection
4Minor defect noticed by most
customersModerately high chance of detection
3Minor defect noticed by some
customers Low:High chance of detection
2Minor defect noticed by
discriminating customersRelatively few failures
Very high chance of detection
1 No effect Remote: Failure is unlikely Almost certain detection
Detection is typically assumed to imply action can be taken
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Investigate & Fix Special CausesQuiz!
Sev Occ Det Result Action1 1 11 1 1010 1 110 1 101 10 1
1 10 10
10 10 1
10 10 10
Take 5 minutes to fill in the results and what action should be taken. Be prepared to discuss results.
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Investigate & Fix Special CausesFMEA Form - Initial Assessment
Process Step/Input Potential Failure Mode Potential Failure Effects
SEV
Potential CausesOCC
Current ControlsDET
RPN
Actions Recommended
What is the process step/ Input under
investigation?
In what ways does the Key Input go wrong?
What is the impact on the Key Output Variables (Customer Requirements) or internal requirements?
How
Sev
ere
is th
e ef
fect
to th
e cu
sotm
er? What causes the Key Input to
go wrong?
How
ofte
n do
es c
ause
or
FM
occ
ur? What are the existing controls and
procedures (inspection and test) that prevent eith the cause or the Failure Mode? Should include an SOP number.
How
wel
l can
you
de
tect
cau
se o
r F
M? What are the actions
for reducing the occurrance of the
Cause, or improving detection? Should
have actions only on high RPN's or easy
fixes.
0
0
0
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Investigate & Fix Special CausesFMEA Form - Long Term History
Current ControlsDET
RPN
Actions Recommended Resp. Actions Taken
SEV
OCC
DET
RPN
What are the existing controls and procedures (inspection and test) that prevent eith the cause or the Failure Mode? Should include an SOP number.
How
wel
l can
you
de
tect
cau
se o
r FM
? What are the actions for reducing the
occurrance of the Cause, or improving detection? Should
have actions only on high RPN's or easy
fixes.
Whose Responsible
for the recommended
action?
What are the completed actions taken with the
recalculated RPN? Be sure to include
completion month/year
0 0
0 0
0 0
0 0
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Investigate & Fix Special CausesFMEA Methodology
Two major approaches: Starting with Cause & Effect Matrix Starting with FMEA directly from the Process Map
We will explain the approach using the C&E matrix, though both approaches are very similar
Spreadsheet tools have been prepared to assist you in the preparation of the FMEA
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Investigate & Fix Special CausesFMEA Methodology - Starting with
C&E Matrix AdvantageAdvantage:: The Cause & Effect Matrix assists the
team in defining the important issues that the FMEA should address by helping to prioritize important customer requirements Process inputs that could potentially impact these
requirements Prioritizing the Key Process Inputs according to
their impact on the Output variables (We want to focus on Inputs that highly impact a large number of Outputs first
The C&E Matrix also provides quantitative output that can be used in the determination of the specific severity ratings for the next stage of the FMEA process
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Investigate & Fix Special CausesFMEA - Step by Step
1. For each process input, determine the ways in which the input can go wrong (failure modes)
2. For each failure mode associated with the inputs, determine effects of the failures on the customer
Remember the internal customers! 3. Identify potential causes of each failure mode4. List the Current Controls for each cause or failure mode5. Create Severity, Occurrence, and Detection rating scales6. Assign Severity, Occurrence and Detection ratings to each
cause7. Calculate RPN’s for each cause8. Determine recommended actions to reduce high RPN’s9. Take appropriate actions and recalculate RPN’s
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Investigate & Fix Special CausesProcess Mapping Examples
ManufacturingManufacturing
Outputs Outputs
• TV of Mix -Quality Check around extrusion
• TV of Mix - Quality Check around extrusion
• Surface Area
• Pore Volume
• Appearance
• pH• Temp• Specific Gravity• Clarity
• Appearance (Color, Wetness)
• Appearance (Color)
• Physical Chemical Properties
• Cycle Time (plugging)
• Zone 3 Temp
MixingWater and
Metals Preparation
ExtrusionExtrude
through die
Dryer Calciner
Material drying, surface
area issues
NADMSolution
Preparation
Impregnation
Metals addition
Fluid Bed DryerFinal
preparation / appearance
issues
Total Rate CMixer Speed CAl2O3 Qual URec Comp U
Ext Rate CDie Wear UExt RPMs CDie Change U
Temperature CRot speed CDraft CFeed Rate CDrying air U
Inputs Types Inputs Types
Nitric Acid CH2O2 CWater CADM CHold Time UAgitation C
Phos Acid CNozzle Type CSpray Time CWater CMoly CNickel CBase C
Temperature CRate CAir Flow CRes Time C
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Investigate & Fix Special CausesC&E Matrix Example
This is the C&E Matrix for the previous Manufacturing Process Map with the Key Inputs sorted by the Total Score
Rating of Importance to Customer 8 8 4 9 10 4 8 8
1 2 3 4 5 6 7 8
Plu
ggin
g C
ycle
Tim
eLe
ngth
D
istri
butio
nP
oros
ity
Dis
tribu
tion
Col
orC
atal
yst
Per
form
ance
Mol
y D
istri
butio
n in
P
elle
tt (w
ithin
&
bet
wee
n)
Dus
t/Fin
es
Con
tent
% M
oly
& %
N
icke
l
Total
Process Step Process Input
Impregnation Moly 9 0 0 3 9 3 9 9 345NADM ADM 9 0 0 1 9 3 9 9 327
Impregnation Two Step / One Step Process 9 0 0 3 9 9 9 3 321Impregnation Base 3 9 9 0 9 3 3 1 266Impregnation Order of Addition 3 0 0 3 9 9 3 3 225Impregnation Water 3 0 0 9 0 9 9 0 213Impregnation Nickel 1 0 0 9 3 0 0 9 191
NADM Nitric Acid 9 0 0 0 3 9 3 1 170NADM Hydrogen Peroxide 9 0 0 0 3 9 3 1 170NADM Water 9 0 0 3 1 3 3 3 169NADM Temperature (Steam Inj) 9 0 0 3 1 3 3 3 169
Fluid Bed Dryer Temp 3 0 0 9 3 0 1 0 143Mixing Al2O3 Quality 1 9 9 0 0 0 3 0 140Mixing Recycle Rate 1 1 1 0 1 3 3 9 138
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Investigate & Fix Special CausesFMEA Worksheet
Before we move to the example let’s look at an FMEA worksheet
The information on this sheet is transferred directly to the FMEA form
The purpose of this worksheet is to focus the team on the FMEA inputs and not on scoring
The scoring should be done after the basic inputs have been madeThe scoring should be done after the basic inputs have been made
FMEA Worksheet.XLSFMEA Worksheet.XLS
Process Step Key Process Input
Failure Modes - What can go
wrong? Effects Causes Current Controls
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Investigate & Fix Special Causes
1. For Each Process Input, Determine the Ways in Which the Input Can Go Wrong (Failure Modes)
We will first deal with the Moly Flow Rate input variable.
Process Step/Input
Failure Modes - What can go
wrong? Effects CausesCurrent Controls
Impregnation/Moly Flowrate
Moly Flowrate is too high
Moly Flowrate is too low
FMEA Step 1
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Investigate & Fix Special Causes
2. For Each Failure Mode Associated with the Inputs, Determine Effects
These effects are internal requirements for the next process and/or to the final customer
Process Step/Input
Failure Modes - What can go
wrong? Effects CausesCurrent Controls
Impregnation/ Moly Flowrate
Moly Flowrate is too high
Off-Spec Material
Plugs dryer
Moly Flowrate is too low
Off-Spec Material
FMEA Step 2
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3. Identify Potential Causes of Each Failure Mode
In most cases, there will be more than one Cause for a Failure Mode but we’ll keep it simple for this exercise
Process Step/Input
Failure Modes - What can go
wrong? Effects CausesCurrent Controls
Impregnation/ Moly Flowrate
Moly Flowrate is too high
Off-Spec Material Weigh Cell Failure
Plugs dryer Weigh Cell Failure
Plugs dryer Operator Error
Moly Flowrate is too low
Off-Spec Material Weigh Cell Failure
Off-Spec Material Operator Error
May elect to list both effects on a single line since they relate to a single cause, and reduce a line in the table.
FMEA Step 3
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4. List the Current Controls for Each Cause
Process Step/Input
Failure Modes - What can go
wrong? Effects CausesCurrent Controls
Impregnation/ Moly Flowrate
Moly Flowrate is too high
Off-Spec Material Weigh Cell Failure DCS Program/Lab Verification
Plugs dryer Weigh Cell Failure DCS Program/Lab Verification
Plugs dryer Operator Error DCS Program/Lab Verification
Moly Flowrate is too low
Off-Spec Material Weigh Cell Failure DCS Program/Lab Verification
Off-Spec Material Operator Error DCS Program/Lab Verification
For each failure mode/cause we list how we are either preventingpreventing the cause or detectingdetecting the failure mode
We will list the procedure number where we have a SOP
We need to be considerate of “holes” in the current controls column…..in this example, there are controls on the operation
FMEA Step 4
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Investigate & Fix Special Causes
5. Create Severity, Occurrence, and Detection Rating Scales
Example Rating ScaleRating Severity of Effect Likelihood of Occurrence Ability to Detect
10 Hazardous without warningVery high:
Can not detect
9 Hazardous with warningFailure is almost inevitable
Very remote chance of detection
8 Loss of primary functionHigh:
Remote chance of detection
7Reduced primary function
performanceRepeated failures
Very low chance of detection
6 Loss of secondary functionModerate:
Low chance of detection
5Reduced secondary function
performanceOccasional failures
Moderate chance of detection
4Minor defect noticed by most
customersModerately high chance of detection
3Minor defect noticed by some
customers Low:High chance of detection
2Minor defect noticed by
discriminating customersRelatively few failures
Very high chance of detection
1 No effect Remote: Failure is unlikely Almost certain detection
FMEA Step 5
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6. Assign Severity, Occurrence and Detection Ratings to Each Cause
We are now ready to transfer the worksheet input to the FMEA form
Copy and paste the worksheet columns into the appropriate FMEA form columns
The team then starts scoring each row to compute the RPN values
Notes: You will only use one Severity value Determine which effect has the highest associated Severity and
use that SEV value for ALLALL causes for the related failure mode (Worst Case)
o When combining effects that have the same cause … Next Slide
FMEA Step 6
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Investigate & Fix Special Causes
6. RPN Component Value AssignmentProcess
Step/InputPotential
Failure ModePotential
Failure Effects
SEV
Potential Causes
OCC
Current Controls
DET
RPN
Impregnation / Moly Flowrate
Moly flowrate is too high.
Off-Spec Material 10 Weigh Cell
Failure 1DCS
Program/Lab Verification
2 20
Off-Spec Material 10 Operator Error 1
DCS Program/Lab Verification
2 20
Plugs dryer 4 Weigh Cell Failure 1
DCS Program/Lab Verification
2 8
Plugs dryer 4 Operator Error 1DCS
Program/Lab Verification
2 8
Moly flowrate is too low.
Off-Spec Material 10 Weigh Cell
Failure 1DCS
Program/Lab Verification
2 20
Off-Spec Material 10 Operator Error 1
DCS Program/Lab Verification
2 20
If you chose to combine these and put both the Off-Spec Material and Plugs dryer in a single effects block, then the SEV score should be 10.
FMEA Step 6 Continued…
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Investigate & Fix Special Causes
7. Calculate RPNs• Multiply the Severity, Occurrence, and Detection values for each line in the
FMEA
• The Excel form automatically calculates the RPN for you
• Then sort all lines by RPN
• Notice that you have to identify all cells so you can carry the failure modes, effects, causes and current controls along with the sort
Process Step/Input
Potential Failure Mode
Potential Failure Effects
SEV
Potential Causes
OCC
Current Controls
DET
RPN
Impregnation / Moly Flowrate
Moly flowrate is too high.
Off-Spec Material 10 Weigh Cell
Failure 1DCS
Program/Lab Verification
2 20
Off-Spec Material 10 Operator Error 1
DCS Program/Lab Verification
2 20
Plugs dryer 4 Weigh Cell Failure 1
DCS Program/Lab Verification
2 8
Plugs dryer 4 Operator Error 1DCS
Program/Lab Verification
2 8
Moly flowrate is too low.
Off-Spec Material 10 Weigh Cell
Failure 1DCS
Program/Lab Verification
2 20
Off-Spec Material 10 Operator Error 1
DCS Program/Lab Verification
2 20
FMEA Step 7
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Investigate & Fix Special CausesRPN Review
Once you calculate the RPN for each failure mode / cause / controls combination, review the results and look for insights Do the gut check - does the Pareto of items make
sense? If not, maybe the ratings given are varying
Determine potential next steps: Data collection Experiments Process improvements Process control implementations
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Investigate & Fix Special Causes
8. Determine Recommended Actions to Reduce High RPN’sNow fill in recommended actions for top RPNs
Actions are recommended for only the high RPN’s
The key is FOCUSFOCUS!
Process Step/Input
Potential Failure Mode
RPN
Actions Recommended Resp.
Impregnation / 2 step 1 step
1 step (solution slimes on surface)
800
1. Define causes. 2. What is on the base? 3. Sample the wet catalyst for slime. 4. Simulate the mechanical effects of plant handling.
LAKE CHARLES / TECH CENTER
Impregnation / 2 step 1 step
1 step (solution slimes on surface)
80
Impregnation / 2 step 1 step
1 step (solution slimes on surface)
32
Impregnation / 2 step 1 step
2 Step appears as 1 Step 32
Go through timing on one cycle of the Honeywell program
CURTIS BAY
FMEA Step 8
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Investigate & Fix Special Causes
9. Take Appropriate Actions and Recalculate RPNs
We have recorded the action taken and the impact on the RPN Notice that this is a nice way to track past activities
The FMEA should be re-evaluated by the group as new recommended actions are identified, completed and recorded
Process Step/Input
Potential Failure Mode
RPN
Actions Recommended Resp. Actions Taken
SEV
OCC
DET
RPN
Impregnation / 2 step 1 step
1 step (solution slimes on surface)
800
1. Define causes. 2. What is on the base? 3. Sample the wet catalyst for slime. 4. Simulate the mechanical effects of plant handling.
LAKE CHARLES / TECH CENTER
Impregnation / 2 step 1 step
1 step (solution slimes on surface)
80
Impregnation / 2 step 1 step
1 step (solution slimes on surface)
32 0
Impregnation / 2 step 1 step
2 Step appears as 1 Step 32
Go through timing on one cycle of the Honeywell program
CURTIS BAY
FMEA Step 9
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Investigate & Fix Special CausesB-326 DI FMEA Example
Prepared by: Glen P. WiegerFMEA Date (Orig) 5 September, 2002 (Rev) 12 September, 2002
Process Step/ I nput Potential Failure Mode Potential Failure Eff ectsSEV
Potential CausesOCC
Current ControlsDET
RPN
I tem Number
What is the process step/ Input under
investigation?
In what ways does the Key I nput go wrong?
What is the impact on the Key Output Variables
(Customer Requirements) or internal requirements?
How
Seve
re is
the
eff
ect
to t
he c
usot
mer?
What causes the Key I nput to go wrong?
How
ofte
n do
es c
ause
or
FM o
ccur
?
What are the existing controls and procedures (inspection and test) that prevent either the cause or the Failure Mode?
Should include an SOP number.
How
well
can
you
dete
ct
or p
reve
nt c
ause
or
FM?
272Cation Production - Filter H2O Flow Flow Too Low
Vessel capacity not utilized before regen required for spacing, results in production loss 9
No flow equilization between vessels 10 None 8 720
283Cation Production - Filter H2O Flow Flow Too Low
Vessel capacity not utilized before regen required for spacing, results in production loss 9
Lack of DCS control logic to control flow 10 None 8 720
291Cation Production - Filter H2O Flow Flow Too High
Unequal spacing of vessel run-lengths, early regeneration resulting in production loss 6
No flow equilization between vessels 10 None 8 480
301Cation Production - Filter H2O Flow Flow Too High
Unequal spacing of vessel run-lengths, early regeneration resulting in production loss 6
Lack of DCS control logic to control flow 10 None 8 480
305Cation Production - Filter H2O Flow Flow Too High
Run lengths shortened due to bottom layer of resin breakthrough, resulting in production loss 6
No flow equilization between vessels 10 None 8 480
315Cation Production - Filter H2O Flow Flow Too High
Run lengths shortened due to bottom layer of resin breakthrough, resulting in production loss 6
Lack of DCS control logic to control flow 10 None 8 480
111Cation Production - Resin Condition
I nsuffi cient exchange capacity
Loss of exchange capacity - results in short run lengths, loss of production, higher regen costs 7
I mproper regeneration (over time) 8 DCS control 7 392
Building 326 DI PlantUtilities Division Six Sigma Team
Process or Product Name:Responsible:
7-53
Investigate & Fix Special CausesB-326 DI FMEA Example
Distribution of PRN Ratings(318 Failure Modes / Eff ects Evaluated)
0
100
200
300
400
500
600
700
800
1 16 31 46 61 76 91 106 121 136 151 166 181 196 211 22 241 25 271 28 301 316
Tota
l Rat
ing
I ncreased I mpact
7-54
Investigate & Fix Special CausesApproaches to FMEA
Approach One (C&E Matrix Focus)Approach One (C&E Matrix Focus) Start with key inputs with the highest scores from the C&E
Matrix analysis Fill out the FMEA worksheet for those Inputs Calculate RPN’s and develop recommended actions for the
highest RPN’s Complete the Process FMEA for other Inputs over time
Approach Two (Customer Focused)Approach Two (Customer Focused) Fill out the failure mode and effects columns of the worksheet.
Copy to FMEA form and rate Severity. For High Severity Ratings, List causes and rate Occurrence
for each Cause For the highest Severity * Occurrence Ratings, evaluate
current controls For Highest RPN’s develop recommended actions
7-55
Investigate & Fix Special CausesApproaches to FMEA Continued…
Approach Three (Comprehensive)Approach Three (Comprehensive) Good approach for small processes Fill out the FMEA worksheet beginning with the
first process step and ending with the last Score SEV, OCC and DET for all causes Develop recommended actions for highest RPN’s
Approach Four (Super Focused)Approach Four (Super Focused) Pick the top Pareto defect item (Damaged
Components) or Failure Mode (Variability in Temperature)
Focus the FMEA process on only that defect or failure mode
Purpose: To “kill” that failure mode
7-56
Investigate & Fix Special Causes
Process Step/Input Potential Failure Mode Potential Failure Effects
SEV
Potential CausesOCC
Current ControlsDET
RPN
Actions Recommended
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
What is the Input
What What can go can go wrong wrong
with the with the Input?Input?
What can What can be done?be done?
What is What is the Effect the Effect
on the on the Outputs?Outputs?
What are What are the the
Causes?Causes?
How can How can these be these be found or found or
prevented?prevented?
How How Bad?Bad?
How How Often?Often?
How How well?well?
FMEA Overview
7-57
Investigate & Fix Special CausesS.C.A.P. Considerations
1) A single joint is above UCL or below LCL2) A run of 8 above or below CL
Target
Time
2) Chronic Problems
Bad
BetterTime
1) Sporadic Problems
Note: S.C.A.P. may need to be specific to the type of instability
7-58
Investigate & Fix Special Causes
Plot Data on Control Chart
Recheck Lab Analysis
ControlChart
Signal?
RecheckValue InsideControl Chart
Limits?
• Adjust Process Variable (Knob)• Wait for Another Sample
NextSample ValueInside ControlChart Limits?
• Delete Original Value• Replace With “New” Value
No
Yes
Yes
No
YesNo
A “Typical” S.C.A.P.
7-59
Investigate & Fix Special CausesA “Suggested” S.C.A.P.
Plot data on Control Chart
ControlChart
Signal?Is
AdjustmentProcess Variable
Appropriate?
Adjust ProcessVariable and CollectAnother Sample as
Soon as Appropriate.
StabilityRestored?
Continueto
Monitor
IsAnother
AdjustmentCalled for?
DocumentActions
&Results
• Process Operating Conditions• Equipment Failure• Raw Material Change• Procedure Deviation
All OK?
Correct Process andCollect Another
Sample as Soon as Appropriate
StabilityRestored?
Continueto
Monitor
“LastResort”
Adjustments
DocumentActions
&Results
Continueto
Monitor
Document allActions, Results
and Additional
Observations
PreventiveAction
Documentation
Documentation
Corrective Action
Investigative Action
Documentation
Compensating Action
No
YesYes
LaboratoryControlStrategy
Yes Yes
Yes
NoNo
No
No
No
Yes
Yes
ProductionControlStrategy
7-60
Investigate & Fix Special Causes
Special Cause DetectedBy Production ControlChart
DoesControl Strategy
Direct Investigating forSpecial Cause in
Laboratory?
Retest Sample
TestResults
Confirmed? Is RangeBetween Test Results
Less Than3.7M?
MeasurementProcess Stable?
(AccuracyMonitoring)
Report Initial TestResult To Production
Check for Special Causein Production Process
No
Yes
Yes
Was DataRecordedCorrectly?
Notify Productionof Lab Problem
Notify Productionof Lab Problem
Find and CorrectSpecial Cause inMeasurement Process(Precision Monitoring)
Find and CorrectSpecial Cause inMeasurement Process(Accuracy Monitoring)
Correct Error
Discard OriginalTest Results
Discard OriginalTest Results
Report CorrectedResults to Production
Retest Sample
Retest Sample
No
No
NoYes
Yes
Measurement System Investigation
7-61
Investigate & Fix Special Causes
%9835 Control Strategy for PM-9877-C Process
Reason for low % 9835, if found:
Action taken:
Out-of-ControlCondition
PossibleCauses
Actionto Take
InvestigativeResults
InvestigatedBy
%9835 above uppercontrol limit for 1
1. Incorrect calculations
1. Recheck all calculations1. Calculations Correct? ____Yes ____No _________
batch or above targetfor 8 consecutivebatches
2. Not enough PM-939 added.
2. a. Check the batch records. b. Check the scales for accuracy. c. Check valves in charging line. d. Check packing gland on Milroyal pump for leaks. e. Check packing gland on autoclave agitator.
2. a. Amount of PM-939 added ______lbs.
b. Scales are accurate? ____Yes ____No
c. Any valves leaking? _____Yes ____No d. Packing gland leaking? ____Yes ____No
e. Agitator packing gland leaking? _______ Yes _______ No
_________
_________
_________ _________
_________Batch Number
__________
3. Overcharge of PM-9835.
3. a. Check the batch records. b. Check the scales for accuracy.
3. a. Amount of PM-9835 charged?_____lbs
b. Scales are accurate? ____Yes ____No
_________
_________
4. Assay of PM-9835 is low or high.
4. a. Check the assay of the PM-9835 used in computer. b. Was thisfirst batch after changing lots of PM-9835?
4. a. PM-9835 assay _____% (in computer)
PM-9835 assay _____% (from vendor)
b. New lot of PM-9835? ____Yes ____No
_________
5. Change in PM-1530 catalyst quality.
5. a. Check if catalyst drum was changed for this batch. b. Sample catalyst.
5. a. New catalyst drum? ____Yes ____No b. 4-ounce sample. Hold for tech staff.
_________
6. Incorrect temperature and/or pressure conditions.
6. Check the batch records and charts.
6. a. Maximum temperature _______C
b. Maximum pressure ________psig
c. Addition time ______hrs ______min
_________
_________
7. Recorders out of calibration.
7. Have the recorders checked for proper calibration.
7. Were the recorders properly calibrated? _______ Yes _______ No
_________
8. Laboratory error.
8. a. Ask lab whether analysis was repeatable. b. Re-sample batch and hold sample for tech staff.
8. a. Laboratory test run in duplicate?
_______ Yes _______ No If no, request that sample be re-run. Record both values on batch record. b. 4-ounce sample. Hold for tech staff.
_________
S.C.A.P. Check Sheet Example
7-62
Investigate & Fix Special CausesKnowledge/Systems Requirements
for a S.C.A.P.Compensating Action
• Criteria for judging if compensating action is appropriate.• What process variable is to be adjusted?• Required effect of process variable adjustment.• Amount of adjustment to obtain the required effect.• Criteria for judging if stability has been restored.
Investigative Action• Standard (Required) Process Operating Conditions.• Equipment failures signals.• Raw material analysis techniques.• Well-defined procedures.
Corrective Action• Well-defined procedures for correcting any deviation detected in the Investigative Action.• “Last Resort” adjustment procedures.• Criteria for judging if stability has been restored.
Documentation•Procedures/Systems for documenting actions, results and additional observations.• Procedures, Lists, charts for accumulating actions, results and additional observations.
7-63
Investigate & Fix Special Causes
• Control Charts provide information, I.e., when to take action and when not to take action.
• People must know what action to take. Actions need to be standardized for all people.
• People control the process, not the control charts.
• Investigation of Assignable Causes and the correction/ prevention of problems should never end.
• Control Charts and the S.C.A.P. need to be reviewed periodically and updated as needed.
• Process Control is the responsibility of Operations. Control Charts need to be in the hands of the people who control the process.
S.C.A.P.
7-64
Investigate & Fix Special Causes
Statistical Process Control
Use SPC to Maintain Current Process
Collect & Interpret
Data
Select Measures
Define Process
IsProcessCapable
?
Improve Process
Capability
IsProcessStable
?
Investigate & Fix
Special Causes
No
Yes
No
Yes
Statistical Process Control (SPC)
is a collection of activities:•Selection of appropriate process
measures•Collection of process data•Graphical analysis of data•Analysis of process stability•Use of data to investigate and
fix special causes in a continuous improvement cycle