Transcript Finding the Root Cause

Finding the Root Cause
Identifying the Context for
Root Cause Investigation
ASQ PALMETTO SECTION
MAY 13, 2008
The Journey Ends (almost). . .
• Review of previous presentations on
addressing audit nonconformance's
• Refresher of CREI problem statement
format
• Every problem originates in a process
• Containment and Interim Actions
• Root Cause Analysis
In Previous Episodes. . .
• The preparation shop makes four types of
Widget blanks for the assembly shop,
named Type A, B, C and D
• Blanks are plastic tubes of various
diameters made on two extruders
• They are temporarily stored in plastic bins
• After storage they are transported to
cutting machines where they are cut to
different lengths
In Previous Episodes. . .
• The assembly shop puts the plastic tubes
together with other products to make a
final assembly
• They are sold to the automobile industry,
specifically Ford and GM
• The Widgets must be at the correct length
(+/- 2mm) and be free of cracks
Getting to the Process of Origin
• Where was the problem found?
• Where is the first process the problem
condition could occur?
• Go to these and any processes in between
to collect data recognizing where the
problem is actually first observed; this is
the process of origin!
• Use a process flow diagram to make this
investigation visual.
Step 3A: Containment – support
identification of Process of Origin
• Purpose: to isolate the
effects of the problem from
downstream processes and
customers; also a source of
data collection for
understanding with depth
and breadth of the problem
and identifying Process of
Origin
• Methods:
–
–
–
–
Planning of containment
Quarantine of product
Evaluation
Data collection
• Inputs:
–
–
–
–
CREI statement
Process flow
Timeline
Data to collect for Is/Is Not
Analysis
• Outputs:
– Data re: scope of problem,
(e.g. how many parts are
actually affected)
– Data for completion of Is/Is
Not Analysis
– Other opportunities
A Root Cause is. . .
A process factor which directly defines
the reason for the problem when it is
present and is having an influence on
the process and its output.
Root Cause Analysis
• Systematic investigation
of a process to identify
the root cause of the
gap, and take corrective
action to eliminate the
gap and keep it from
occurring again in the
future
• The Process of Origin
must be identified,
(using data), before
Root Cause Analysis
can proceed!
Process Hierarchy
Products/Services = output of producing Processes
Producing Processes to accomplish Plans
Planning Processes apply System
to fulfill customer requirements
System Processes = Policies, Objectives & Practices
(how an organization does business)
Audit findings are typically identified at Plan & System level
4 Levels of Root Cause
Defect/Detection Cause = Product level
Direct Process Cause = at Process of Origin
Actual Root Cause = previous process factors
contributing to Process Root Cause, (planning)
System Root Cause = management system
policy/practice contributing to Actual Root Cause
Dig! How Deep?
• Management decides
on depth of root
cause investigation
through the
establishment of
SMART goals for
each problem solving
effort.
Root Cause Analysis Levels
Root Cause
Consideration
Tools
Other
(Wide)
Product
Defect/Detection
cause
Condition of
controls to
detect problem
Control
Barrier
Analysis
What other
products have
similar
controls?
Process
Direct process
cause, (trigger at
process of origin
Factors at
process of
origin triggering
problem, (5Ms)
Fishbone,
(cause &
effect)
What
processes
have similar
trigger cause?
Plan
Actual root cause,
(led to trigger
cause)
Linkage to
planning
processes that
trigger cause
5 Why with
Hypothesis
testing
What other
processes
affected?
System
“weakness” in
mgt. policies or
practices
Linkage of mgt.
system to
actual cause
System
Cause
Analysis
Level
(Deep)
Other affected
mgt. policies
Failure Modes & Effects Analysis
(FMEA) – Clues for Root Cause Investigation
Process
Function
Requirements
Potential
Failure
Modes
Potential
Failure
Effects
Potential
Failure
Causes
Current
Product &
Process
Controls
Process of
origin
Technical
definition of
problem
Symptom
Process
factors = root
causes
Interim
actions
Step 3B: Interim Action
Identifying “Product-level” Root Cause
(Defect Detection Cause)
• Inputs:
• Purpose: to understand why
the problem condition escaped
the process/organization;
evaluation of existing process
controls for
weaknesses/deficiencies;
addressing this cause does not
prevent recurrence of the
problem
• Methods:
– Control barrier analysis
– Planning of interim actions
–
–
–
–
CREI statement
Process flow
FMEA
Control plan
• Outputs:
– Defect, (detection), cause,
(why problem escaped
existing controls)
– Interim controls
– Data for Is/Is Not Analysis
– Methods for monitoring interim
controls to collect data for
problem solving effort
– Other opportunities
Control Barrier Analysis
Worksheet
Process
Condition
Other Opportunities:
Control
Status Capability
Observations
Actions
Results of Control Barrier Analysis
• May recognize missing controls or controls not working
as planned
• Interim actions represent solutions to addressing these
concerns but should not be accepted as the
permanent solution
• When the results of this analysis uncover additional
problems, refer these to the team champion for
direction on addressing, (Other Opportunities)
• Team’s main focus at this point is to implement some
type of control to protect downstream processes from
continuing to experience the problem
• Solutions based on this level of “root cause
investigation” mainly are reactive in nature; they only
improve our ability to detect the problem condition but
don’t typically do anything about addressing the root
cause!
Direct Process Cause
(Trigger Cause at Process of Origin)
• Must confirm process of origin in order to conduct
investigation of process-level root cause!
• Relates one or more factors of the affected
process, (process of origin), not “behaving” as
required to obtain the desired output result at that
process
• Use Cause & Effect diagram, (fishbone technique)
• Direct process causes, (trigger causes), are the
starting point for identifying actual root cause
• Some action may be required to address the direct
process/trigger cause but actions should not be
taken until actual root cause is known
Fishbone Diagram
PROCESS:
Material
Man
Gap:
Mother
Nature
Method
Machine
Fishbone Process
• Involve personnel from process of origin in
brainstorming of potential causes at the process of
origin triggering the problem
• Develop a sketch/list of the process factors, (man,
material, machines, methods, mother nature), related
to the process of origin
• After brainstorming, review each identified cause to
establish:
– If the cause is actually a factor at the process of origin
– If the cause makes sense based on the operational definition
of the problem
• Prioritize remaining causes as to their possible
contribution to the problem condition
• Develop hypothesis test to evaluate each potential
cause at the process of origin
Actual Root Cause
• Explains why trigger cause/condition exists at the
process of origin
• Typically found in previous “planning” processes
• Use 5 Why Analysis with Hypothesis testing to identify
and confirm, (collect data!)
• Many problems have multiple causes
• Usually only one over-riding cause that when addressed,
can significantly reduce the problems impact on the
organization
• Very complex problems may have interacting causes but
these are typically viewed as isolated problems that only
repeat infrequently, (often managed as Just Do It), until
resources allow necessary time to discover interaction
through data collection, analysis and experimentation
5 Why Analysis
• Ask “Why does this
happen?” for each identified
process cause from Cause &
Effect diagram
• Differentiates between
process, (direct) cause and
underlying root cause
• Each level of causes
identified in 5 Why analysis
must also be confirmed via
testing in order to verify root
cause
• Deeper levels of 5 Why
Analysis which get into
Planning processes will
require interview-type data
collection
Root Cause Analysis Plan
• Identify causes to be investigated
• What data supports each cause?
• Can cause be introduced and removed to
confirm presence/absence of problem?
• What tests will be performed to confirm root
cause?
• What is the statistical confidence of these
tests? (i.e. how much data is needed?)
• Results of tests recorded and analyzed with
conclusions drawn
System Causes
• What in the system allowed this problem/cause
to occur
• Identifies why the process root causes occurred
based on current management policies/practices
• Often not readily measurable
• Data obtained through interview
• By identifying system causes, systemic
improvement can be made in order to prevent
recurrence of problem in other similar processes
• Typically addressed once process root causes of
problem are known and confirmed
System Cause Analysis Worksheet
Operational Definition:
Process of origin cause:
Process root cause:
Which management system process is the process root cause related
to?
Who is responsible for this management system process?
What documentation/policies are available describing actions and
controls for this management system process?
Does this documentation/policy recognize the possibility for this
problem to occur?
Are there any current management system controls in place to
prevent or detect this problem?
Has this management system process been associated with previous
problems?
What other processes within the organization are driven by this
management system process?
Possible Management System Level Solutions: 1) Create new policy
2) Change existing policy 3) Reinforce/re-apply current policy
As a result of Root Cause Analysis
• Product-level cause, (related to current controls),
identified and confirmed along with appropriate
interim controls to “protect” downstream
processes/customers
• Trigger cause at process of origin identified and
confirmed
• Actual root cause, (what allowed the trigger
cause to exist at the process of origin), known
and confirmed
• System root cause identified, relating actual root
cause to management policies/practices
A Key Outcome of Every Problem
Solving/Root Cause Investigation. . .
Expansion of Knowledge
Next Steps, (Next Year?)
• Solution identification, (3 possible
solutions to every problem), and
evaluation/selection for each root cause
level
• Implementation of selected solutions
• Verification of the effectiveness of
implemented solutions
• Lessons learned
Your Turn for Root Cause Analysis
• For previous case study on widget
manufacture:
– CREI statement, (given)
– Process flow, (given)
– Is/Is Not analysis, (given; process of origin
known)
– Fishbone potential causes at process of origin
– Create questions for 5 Why investigation
Widget CREI
• Concern: customer complaint from GM
re: cracked tubes, (widgets)
• Requirement: per GM drawing #123,
assembly should be free from cracks
• Evidence: GM customer complaint
• Impact: assembly leaks, (performance),
GM is requiring contained shipping, ($$$)
Widget Making Process Flow
Extrude
Store extruded
pieces
Cutting
Assembly
Final inspection
Ship to customer
Is/Is Not Analysis
Focus
Aspect
Data to
Collect
Where to
Collect
How to
Collect
Results –
IS
Results –
IS NOT
Comments
What?
Problem
condition
# cracked
tubes
Process
flow
Visual
evaluation
Visible
cracks on
tubes
Other
defects
Refer to
requirement
Where?
Geographicall
y
Processe
s where
cracked
tubes
found
Process
flow
Note
processes
where
cracked
tubes found
Cutting,
customer
Extrusion,
assembly,
final
inspection
See process
flow
Where?
On output
Location
on part
During
containmen
t
Concentratio
n diagram
Cracks at
edge of
tube
Cracks
along
length or
in other
locations
Refer to
problem
condition
When?
First seen
Problem
report
Customer
service
Review of
customer
complaints
4/28/08,
(date of
customer
complaint
)
Prior to
this date
Refer to
timeline
Who?
Identified
problem
Names,
positions,
contact
info
Customer
service
Interview
GM,
(customer
)
Other
customers
Involved in
related
Functions
Process
flow
Interview
Cutting
operator
Other
cutting
Refer to
process flow
Fishbone Diagram
PROCESS: Cutting
Material
Man
Cracks on
cut edge of
tube
produced
on 3rd shift
on 4/28/08
Mother
Nature
Method
Machine
Possible Questions for
5 Why Analysis
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