Law

1
Law Order Police Investigation Exhaustive
interrogation of inputs to link suspect to the
crime
2
CSI Scientific Investigation Exhaustive
interrogation of outputs to link suspect to the
crime
3
Cause Effect Diagram Prioritised interrogation
of Inputs to find Relationship to Output
4
Shainin Philosophy Scientific Investigation of
the Process Output to determine the Red X!
5
X
The Shainin Philosophy
For every effect there is a principal cause, the
Red X The fastest route to the Red X is a
progressive search KISS (Keep It Statistically
Simple)
1 2 3
6
X
The Shainin Philosophy
For every effect there is a principal cause, the
Red X The fastest route to the Red X is a
progressive search KISS (Keep It Statistically
Simple)
1 2 3
7
Dictionary Game
A word has been selected at random from a
dictionary. Youre allowed only questions that
can be answered yes or no. The Red X is
like the secret word. We need to generate clues
(and find solutions) as efficiently as possible.
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Process of Elimination
Power of Convergence
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An Un-alphabetised Dictionary?
Cause and Effect Analysis (a.k.a. The Fishbone
Diagram)
39 possible root causes to investigate
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Dictionary
From 1656 pages to 25 pages in 6
questions (98 reduction)
This flow-down chart documents our progressive
search
Whats your next question?
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The strategy we use to split the dictionary will
be determined based upon the realities faced by
the project. (If the dictionary were organised
by some method other than alphabetical order, our
questions would have been different.) There are
two main approaches to Progressive Search
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If the CTQ described in the Focused Problem
Definition is a variable, the first layer of the
flow-down chart will probably be analysed using
Multi-vari and other variable tools. If the CTQ
described in the Focused Problem Definition is an
attribute, the first layer of the flow-down chart
will probably be analysed using Chi-square.
13
If the CTQ described in the Focused Problem
Definition deals with an assembly that can be
taken apart and re-assembled without damaging the
components themselves, a Component Search should
probably be considered.
14
Flow-down Chart
ANALYSE Layer(s) of Analysis and Identification
of the Red X
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BIG PICTURE
A good Flow-down Chart givesyou both
LSL
USL
CTQ
AND
Measurement Variation
Process Variation
details details details details
16
A good Flow-down Chart gives you both
17
Dice
240 dice are resting on a table. All are
identical except one which is lighter in weight
than the rest. You are given a balance and a set
of calibrated weights. Find the light die in 5
steps.
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240 Dice
Divide in 3 groups of 80
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(No Transcript)
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Multi-vari
Shainin Example

• A subcontractor to Pratt Whitney was making
  fuel pump rotor for jet engines.
• Problems had been blamed on the lathe, another
  was about to be ordered for 70,000
• Shainin said What if its not the machine?
• He was given 24 hours to find the answer,
  otherwise the lathe would be ordered.
• Foreman said it was tool wear!
• Engineering didnt know (or it would have been
  solved)
• So, Shainin began with talking to the parts.

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Multi-vari
Fuel Pump Rotor Shaft
0.250 0.001
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Detailed Measurements
C
D
Free End
A
D (minimum)
B
C (maximum)
Collet End
B (minimum)
A (maximum)
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Flow-down Chart
Excessive Variation in Rotor Shaft Diameter
Required
Existing
0.249 0.251 Rotor Shaft
Diameter (inches)
Measurement Variation
Process Variation
Isoplot
Time to Time
Part to Part
Within Part
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Families of Variation
For this problem...
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Multi-vari Chart
Upper Spec Nominal Lower Spec
26
Flow-down Chart
Excessive Variation in Rotor Shaft Diameter
Required
Existing
0.249 0.251 Rotor Shaft
Diameter (inches)
Measurement Variation
Process Variation
Isoplot
Time to Time
Part to Part
Within Part
Direction of Change
Tool Wear
Heat
Coolant
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Fuel Pump Rotor Shaft
Red X was overheated coolant. But what else did
you notice about the Multi-vari? All 15 results
had the same shape, i.e. the collet
measurements were greater than those on the free
end.
Guide rail induced taper was the Pink X. What
else? Out-of roundness, due to a worn bearing.
The lathe as it was found by Shainin had a
capability of 3.5 - 4 sigma. With improvements,
the lathe achieved 15 sigma capability.
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Families of Variation
1. Each project has its own particular families
of variation (may be more numerous than just
three). Families CANNOT be copied blindly from
one project to another, however, starting with
the basic three families of Time to Time, Unit to
Unit and Within Unit can allow to discern the
other families more easily. 2. Families of
variation are NOT variables. Things like guide
rail alignment and temperature will appear as
children in the families which have been
identified. 3. Only show the children of the
family containing the Red X - listing the
children for other families will be wasted effort
since those families inevitably wont contribute
nearly as much to the problem.
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Families of Variation Unit to Unit
Spool
Lot
Part
GroupingsConsider a scenario where a CTQ of
material hardness is being studied. Raw copper
is received in lots and each lot consists of
several spools. Each spool produces hundreds of
copper parts. Appropriate grouping families
would includeLot to lot Spool to spool Part
to part
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Families of Variation Within Unit
Parallel pathsConsider a project focusing on
record processing time. There are four different
offices entering data into a central database.
The records are processed at each office by one
of five clerks and are entered using either a
barcode system or by typing it in manually.
Appropriate parallel path families would
includeOffice to office Clerk to clerk Bar
code vs. manual NOTE Beware of the pitfall of
omitting the (non-parallel path) family of record
to record. This family should also be included
in the Solution Tree.
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Families of Variation Within Unit
Oven Rack Layout
Printed Circuit Card
Within type familiesA certain project was
focused on the signal strength of the electronic
components on a printed circuit card at a
functional test. At one point in the process,
the cards would get baked in an oven in sixteen
card batches. Appropriate Within families
would includeWithin Rack Within Card
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Families of Variation
Time to time families Time to time is, present
in every project in some form or another. Most
often, the time the process is performed is
almost exactly the same as the time of detection.
That being the case, the only remaining question
is what increment of time makes sense in light of
the nature of the process? (e.g., hour to hour,
shift to shift, day to day, month to month?)
For some reliability projects, another time to
time family may be considered the time to time
family that considers when in time the incident
occurred since this is much different from when
the defect was created.
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Families of Variation
Problem Defined
Process Variation
Measurement Variation
Time To Time
Within Unit
Unit To Unit
Side to Side Position to Position Operator to
Operator Machine to Machine Plant to Plant Centre
to Edge
Sequence Hour to Hour Shift to Shift Day to
Day Week to Week
Batch to Batch Lot to Lot Group to Group
Reference World Class Quality, 2nd Ed., KR Bhote
AK Bhote, AMACOMUSA, 2000.