1. Control Phase Defect Prevention

2. Six Sigma Control Plans
Defect Controls
Six Sigma Control Plans
Defect Controls
Lean Controls
Welcome to Control
Wrap Up & Action Items
Realistic Tolerance and Six Sigma Design
Process Automation or Interruption
Poka-Yoke
In an effort to put in place Defect Controls we will examine Tolerances, Process Automation and Poka-Yoke.

3. Purpose of Defect Prevention in Control Phase
Process improvement efforts often falter during implementation of new operating methods learned in the Analyze Phase.
Sustainable improvements can not be achieved without control tactics to guarantee permanency.
Defect Prevention seeks to gain permanency by eliminating or rigidly defining human intervention in a process.
With defect prevention we want to ensure that the improvements created during the project stay in place.
Yes sir, we are in CONTROL!

4. s Level for Project Sustaining in Control
BEST
5-6s: Six Sigma product and/or process design eliminates an error condition OR an automated system monitors the process and automatically adjust critical X’s to correct settings without human intervention to sustain process improvements
4-5s: Automated mechanism shuts down the process and prevents further operation until a required action is performed
3-5s: Mistake proofing prevents a product/service from passing onto the next step
3-4s: SPC on X’s with the special causes are identified and acted upon by fully trained operators and staff who adhere to the rules
2-4s: SPC on Y’s
1-3s: Development of SOPs and process audits
0-1s: Training and awareness
Please read the slide.
WORST

5. 6s Product/Process Design
Designing products and processes such that the output Y meets or exceeds the target capability.
When designing the part or process, specifications on X are set such that the target capability on Y is achieved.
Both the target and tolerance of the X must be addressed in the spec limits. 20 19 18 17 16 15 14 13 12 11 10 24 22 21
Distribution of X
Distribution
of Y
Relationship Y = F(x)
Specification on Y
The best approach to defect prevention is to design Six Sigma right into the process.

6. Product/Process Design20 19 18 17 16 15 14 13 12 11 10 24 22 21
Distribution of X
Distribution
of Y
Relationship Y = F(x)
Specification on Y
Upper Prediction Interval
Lower Prediction Interval
If the relationship between X and Y is empirically developed through Regressions or DOE’s uncertainty exists.
As a result, confidence intervals should be used when establishing the specifications for X.
Please read the slide.

7. Product/Process Design Example
Using 95% prediction bands within MINITABTM
Stat > Regression>Fitted Lin Plot …..Options…Display Prediction Interval 5 10 20 30 40 50 60 70 80 90
Input
Output
Y = X
R-Sq = 88.0 %
Regression
95% PI
Regression Plot
What are the
spec limits for
the output?
What is the tolerance range for the input?
If you want 6 performance, you will remember to tighten the output’s specification to select the tolerance range of the input.
Generate your own Data Set(s) and experiment with this MINITABTM function.
Usually we use the prediction band provided by MINITABTM. This is controllable by manipulation of the confidence intervals. 90%, 05%, 99%, etc. Play with adjusting the prediction bands to see the effect it has.

8. Product/Process Design Example
Note: High output spec connects
with top line in both cases.
Lower input spec
Using top output spec determines high or low tolerance for input depending on slope of Regression. .

9. Poor Correlation does not allow for tighter tolerancing.
Poor Regression Impacting Tolerancing
Poor Correlation does not allow for tighter tolerancing.
Please read the slide.

10. Automatic gauging and system adjustments
5 – 6  Full Automation
Full Automation: Systems that monitor the process and automatically adjust Critical X’s to correct settings.
Automatic gauging and system adjustments
Automatic detection and system activation systems - landing gear extension based on aircraft speed and power setting
Systems that count cycles and automatically make adjustments based on an optimum number of cycles
Automated temperature controllers for controlling heating and cooling systems
Anti-Lock braking systems
Automatic welder control units for volts, amps and distance traveled on each weld cycle
Automation can be an option as well which removes the human element and its inherent variation. Although use caution to automate a process, many time people jump into automation prematurely. If you automate a poor process what will that do for you?

11. Full Automation Example
A Black Belt is working on controlling rust on machined surfaces of brake rotors:
A rust inhibiter is applied during the wash cycle after final machining is completed
Concentration of the inhibiter in the wash tank is a Critical X that must be maintained
The previous system was a standard S.O.P. requiring a process technician to audit and add the inhibiter manually
As part of the Control Phase, the team has implemented an automatic check and replenish system on the washer.
Full Automation
Don’t worry boss, it’s automated!!
Review this example of full automation.

12. 4 – 5 s Process Interruption
Process Interruption: Mechanism installed that shuts down the process and prevents further operation until a required action is preformed:
Ground fault circuit breakers
Child proof caps on medications
Software routines to prevent undesirable commands
Safety interlocks on equipment such as light curtains, dual palm buttons, ram blocks
Transfer system guides or fixtures that prevent over or undersized parts from proceeding
Temperature conveyor interlocks on ovens
Missing component detection that stops the process when triggered
This can be OK sometimes.

13. 4 – 5 s Process Interruption
Example:
A Black Belt is working on launching a new electric drive unit on a transfer system
One common failure mode of the system is a bearing failure on the main motor shaft
It was determined that a high press fit at bearing installation was causing these failures
The root cause of the problem turned out to be undersized bearings from the supplier
Until the supplier could be brought into control or replaced, the team implemented a press load monitor at the bearing press with a indicator
If the monitor detects a press load higher than the set point, it shuts down the press and will not allow the unit to be removed from press until an interlock key is turned and the ram reset in the manual mode
Only the line lead person and the supervisor have keys to the interlock
The non-conforming part is automatically marked with red dye
Process Interruption
This is a real world example.

14. See if you can find the Poka- Yokes!
3 – 5  Mistake Proofing
Mistake Proofing is best defined as:
Using wisdom, ingenuity, or serendipity to create devices allowing a 100% defect free step 100% of the time
Poka-Yoke is the Japanese term for mistake proofing or to avoid “yokeuro” inadvertent errors “poka”.
See if you can find the Poka- Yokes!
Mistake proofing is great because it is usually inexpensive and very effective. Consider the many everyday examples of mistake proofing. You can not fit the diesel gas hose into an unleaded vehicle gas tank. Pretty straightforward, right?

15. Traditional Quality vs. Mistake Proofing
Traditional Inspection
Result
Worker or
Machine Error
Don’t Do
Anything
Defective
Sort
At Other
Step
Discover
Error
Take Action/
Feedback No
Defect
Source Inspection
“KEEP ERRORS FROM
TURNING INTO DEFECTS”
Next
This clearly highlights the difference between the two approaches. What are the benefits to the Source Inspection method?

16. Styles of Mistake Proofing
ERROR ABOUT TO OCCUR
DEFECT ABOUT TO OCCUR
(Prediction)
WARNING SIGNAL
CONTROL / FEEDBACK
SHUTDOWN
(Stop Operation)
ERROR HAS OCCURRED
DEFECT HAS OCCURRED
(Detection)
There are 2 states of a defect which are addressed with mistake proofing.
Mistake Proofing Approaches
Please read the slide.

17. Mistake Proofing Devices Design
Hints to help design a mistake proofing device:
Simple
Inexpensive
Give prompt feedback
Give prompt action (prevention)
Focused application
Have the right people’s input
BEST makes it impossible for errors to occur
BETTER ……allows for detection while error is being made
GOOD detects defect before it continues to the next operation
The very best approaches make creating a defect impossible, recall the gas hose example, you can not put diesel fuel into an unleaded gas tank unless you really try hard or have a hammer.

18. Types of Mistake Proof Devices
Contact Method
Physical or energy contact with product
Limit switches
Photo-electric beams
Fixed Value Method
Number of parts to be attached/assembled etc are constant
Number of steps done in operation
Motion-step Method
Checks for correct sequencing
Checks for correct timing
Photo-electric switches and timers 1
Guide Pins of
Different Sizes 2
Error Detection
and Alarms 3
Limit Switches 4
Counters 5
Checklists
Please read the slide.

19. Mistake Proofing Examples
Everyday examples of mistake-proofing:
Home
Automated shutoffs on electric coffee pots
Ground fault circuit breakers for bathroom in or outside electric circuits
Pilotless gas ranges and hot water heaters
Child proof caps on medications
Butane lighters with safety button
Computers
Mouse insertion
USB cable connection
Battery insertion
Power save feature
Automobile
Seat belts
Air bags
Car engine warning lights
Office
Spell check in word processing software
Questioning “Do you want to delete” after depressing the “Delete” button on your computer
Factory
Dual palm buttons and other guards on machinery
Retail
Tamper proof packaging
Let’s consider examples of mistake proofing or Poka-Yoke devices even in the home. Have a discussion about them in the work environment as well.

20. Advantages of Mistake Proofing as A Control Method
Mistake Proofing advantages include:
Only simple training programs are required
Inspection operations are eliminated and the process is simplified
Relieves operators from repetitive tasks of typical visual inspection
Promotes creativity and value adding activities
Results in defect free work
Requires immediate action when problems arise
Provides 100% inspection internal to the operation
The best resource for pictorial examples of Mistake Proofing is:
Poka-Yoke: Improving Product Quality by Preventing Defects.
Overview by Hiroyuki Hirano. Productivity Press, 1988.)
To see a much more in-depth review of improving the product or service quality by preventing defects you MUST review the book shown on this slide. A comprehensive 240 Poka-Yoke examples are shown and can be applied to many industries. The Poka-Yoke’s are meant to address errors from processing, assembly, mounting, insertion, measurement, dimensional, labeling, inspection, painting, printing, misalignment and many other reasons.

21. Defect Prevention Culture and Good Control Plans
Involve everyone in Defect Prevention:
Establish Process Capability through SPC
Establish and adhere to standard procedures
Make daily improvements
Invent Mistake-proofing devices
Make immediate feedback and action part of culture
Don’t just stop at one mistake proofing device per product
Defect Prevention is needed for all potential defects
Defect Prevention implemented MUST be
documented in your living FMEA for the
process/product
All of the Defect Prevention methods used must be documented in your FMEA and the Control Plan discussed later in the Control Phase.

22. Talk with your fellow workers about:
Class Exercise
Take a look around your work area or office to see what things you can identify as mistake proofed.
Talk with your fellow workers about:
How was the need for the control system identified?
If a Critical X is mistake proofed, how was it identified as being critical?
How are they maintained?
How are they verified as working properly?
Are they ever disabled?
Look for other areas where such beneficial things could be applied.
Exercise.

23. Class Exercise about Defect Prevention
Prepare a probable Defect Prevention method to apply to your project. List any potential barriers to implementation.
Exercise.

24. At this point, you should be able to:
Summary
At this point, you should be able to:
Describe some methods of Defect Prevention
Understand how these techniques can help with project sustainability:
Including reducing those outliers as seen in the Advanced Process Capability section
If the vital X was identified, prevent the cause of defective Y
Understand what tools must document the Defect Prevention created in the Control Phase
Please read the slide.

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