Title: The Quality Improvement Model
1TheQualityImprovementModel
Define Process
Select Measures
Collect Interpret Data
Investigate Fix Special Causes
IsProcessStable?
Investigate Fix Special Causes
No
- Purpose
- Assure stability of the measures.
- Establish permanency of solutions to recurring
special causes. - Improve procedures and training.
Yes
IsProcessCapable?
No
Improve Process Capability
Yes
Use SPC to Maintain Current Process
2Unstable Process
How do we improve an unstable process?
3Potential 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
4The Improvement Process
Diagnose
Solve
- 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.
5Special 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.
Actions 1) Investigation 2) Compensation 3)
Documentation 4) Correction 5) Prevention
Note This is the most important part in
implementing S.P.C.
6Investigative Action
- Systematic detective work to determine the root
source of the special cause. The investigative
actions should be directed toward determining
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..
7Compensating 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.
8Documentation
Recording the suspected cause of the problem,
what actions were taken and how effective the
action was. Benefits
9Pareto of Causes
Note Putting resources to eliminating Cause D
will result in most significant Impact on
process improvement.
10Corrective 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.
11Preventive 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.
12Control To A Standard
- A standard way to perform a task.
- A standard range that a key process variable
should be within. - Standards should be audited.
Note S.O.P.'s NOT being followed can be a major
reason for instabilities on control charts!
13Why S.C.A.P.'s?
- 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.
14Remember The CE Matrix
Note CE is a good place to start building
control strategies. This information will be used
to develop a Failure Modes Effect Analysis (FMEA)
15FMEA Definition
- 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 Directive Identify ways the product or
process can fail and eliminate or reduce the risk
of failure
16Role of FMEA
- Key tool of process team to improve the process
in a preemptive manner (before failures occur) - Used to prioritize resources to insure process
improvement efforts are beneficial to customer - Used to document completion of projects
- Should be a dynamic document, continually
reviewed, amended, updated
17Purposes of FMEA
- Analyzes new processes
- Identifies deficiencies in the process control
plan - Establishes the priority of actions
- Evaluates the risk of process changes
- Identifies potential variables to consider in
Exploratory Data Analyses (EDA) and Design of
Experiments (DOE) studies - Guides the development of new processes
- Helps set the stage for breakthrough
18FMEA Inputs and Outputs
- Inputs
- Process map
- CE matrix
- Process history
- Process technical procedures
- Outputs
- List of actions to prevent causes or to detect
failure modes - History of actions taken
19FMEA Team
- Team approach is necessary
- Recommended representatives
- Design
- Practitioners / Operators / Supervisors
- Quality
- Reliability
- Maintenance
- Materials
- Testing
- Supplier
20FMEA Terms
- Failure Mode
- Effect
- Cause
- Current Controls
- Severity, Occurrence, Detection
- Risk Priority Number (RPN)
Next, Going to define each of these terms
21Failure Mode - Definition
- Failure 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 - Anything that an operator can see thats wrong is
considered a failure mode - Examples
- Incorrect PO number
- Sample Size too small
- Dropped call (customer service)
- Temperature too high
- Surface contamination
- Paint too thin
22Effect - Definition
- Effect - impact on customer requirements
- Generally external customer focus, but can also
include downstream processes - Examples
- 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
23Cause - Definition
- Cause
- 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 - Examples
- 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
24Current Controls - Definition
- Current 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, SOPs,
preventive maintenance, etc.
25Risk 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 - the potential failure modes,
- the effects, and
- 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
RPN Severity X Occurrence X Detection
26Definition of RPN Terms
- Severity (of Effect)- importance of effect on
customer requirements - could also be concerned
with safety and other risks if failure occurs
(1Not Severe, 10Very Severe) - 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 (1Not Likely, 10Very Likely) - 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
- 1Likely to Detect, 10Not Likely at all to Detect
27"Example" Rating Scale
Detection is typically assumed to imply action
can be taken
28FMEA Form - Initial Assessment
29FMEA Form - Long Term History
30FMEA Methodology
- Two major approaches
- Starting with Cause Effect Matrix
- Starting with FMEA directly from the Process Map
- We will explain the approach using the CE
matrix, though both approaches are very similar - Spreadsheet tools have been prepared to assist
you in the preparation of the FMEA
31FMEA Methodology - Starting with CE Matrix
- Advantage 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 CE 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
32FMEA - 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
mode 4. List the Current Controls for each cause
or failure mode 5. Create Severity, Occurrence,
and Detection rating scales 6. Assign Severity,
Occurrence and Detection ratings to each
cause 7. Calculate RPNs for each
cause 8. Determine recommended actions to reduce
high RPNs 9. Take appropriate actions and
recalculate RPNs
33Process Mapping Examples
34FMEA Step 1
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.
35FMEA Step 2
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
36FMEA Step 3
3. Identify Potential Causes of Each Failure Mode
In most cases, there will be more than one Cause
for a Failure Mode but well keep it simple for
this exercise
May elect to list both effects on a single line
since they relate to a single cause, and reduce a
line in the table.
37FMEA Step 4
4. List the Current Controls for Each Cause
For each failure mode/cause we list how we are
either preventing the cause or detecting 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
38FMEA Step 5
5. Create Severity, Occurrence, and Detection
Rating Scales
Example Rating Scale
39FMEA Step 6
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 ALL causes
for the related failure mode (Worst Case) - When combining effects that have the same cause
Next Slide
40RPN 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
41Approaches to FMEA
- Approach One (CE Matrix Focus)
- Start with key inputs with the highest scores
from the CE Matrix analysis - Fill out the FMEA worksheet for those Inputs
- Calculate RPNs and develop recommended actions
for the highest RPNs - Complete the Process FMEA for other Inputs over
time - 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 RPNs develop recommended actions
42Approaches to FMEA Continued
- 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 RPNs
- 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
43S.C.A.P. Considerations
1) A single joint is above UCL or below LCL 2) A
run of 8 above or below CL
Note S.C.A.P. may need to be specific to the
type of instability
44Measurement System Investigation
45Knowledge/Systems Requirementsfor a S.C.A.P.
46S.C.A.P.
- 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.
47Statistical Process Control
- 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