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--Dr. Himanshu TrivediDr. Himanshu Trivedi--General ManagerGeneral Manager
--Quality Management and MethodsQuality Management and Methods--Bosch Rrexroth India LtdBosch Rrexroth India Ltd
Statistical Quality
Control
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What is Quality?What is Quality?
Quality is the total composite product andQuality is the total composite product andservice characteristics of marketing,service characteristics of marketing,
engineering, manufacturing and maintenanceengineering, manufacturing and maintenancethrough which the product and service in usethrough which the product and service in use
will meet the expectations by the customer.will meet the expectations by the customer.
(Armand(Armand FeigenbaumFeigenbaum))
Ability of a set of inherent characteristics of aAbility of a set of inherent characteristics of a
product, system or process to fulfillproduct, system or process to fulfill
requirements of customers and otherrequirements of customers and other
interested parties.interested parties. AS/NZS ISO9000:2000AS/NZS ISO9000:2000
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What comes to your mind whenWhat comes to your mind when
you think about Quality ?you think about Quality ?High performanceHigh performance
Meeting intended requirementsMeeting intended requirements
Meeting specificationsMeeting specifications
Zero defectZero defectFit for useFit for use
Value for moneyValue for moneyGood aestheticGood aesthetic
Good serviceGood service
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Quality GurusQuality Gurus
DemingDeming
JuranJuran
IshikawaIshikawa
FeigenbaumFeigenbaumCorsbyCorsby
..
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GRAPHICAL PICTURE OFGRAPHICAL PICTURE OF
QUALITY JOURNEYQUALITY JOURNEY
GAP
1950 1960 1975 2000
WESTERN
JAPAN
1970 20201990
INDIA
Q
UA
L
I
TY
I
N
D
E
X
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Evolution of TQM
Inspection Quality
ControlTQC
Sampling
1920 1940 1950 1970Time
TQM1980
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100 % Inspection
End of line RejectionIn %
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Is 100% inspection full proof ?Is 100% inspection full proof ?
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Sampling Inspection
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QUALITY CONTROL(QC)QUALITY CONTROL(QC)
Operational techniques and activitiesOperational techniques and activities
that are used to fulfill requirements forthat are used to fulfill requirements forquality.quality. It involves operationalIt involves operational
techniques and activities aimed both attechniques and activities aimed both at
monitoring a process and at eliminatingmonitoring a process and at eliminating
causes of unsatisfactory performance atcauses of unsatisfactory performance at
all stages of Quality Loop in order toall stages of Quality Loop in order toachieve economic effectiveness.(achieve economic effectiveness.(
ISO8402:1994 Sec.3)ISO8402:1994 Sec.3)
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Q Control & Q ImprovementQ Control & Q Improvement
Choose control subjectChoose control subject
Choose units ofChoose units of
measuremeasureSet goalsSet goals
Create SensorCreate Sensor
Measure actualMeasure actualperformanceperformance
Interpret the differenceInterpret the difference
Take action on theTake action on thedifferencedifference
Prove the need
Identify projects
Organise project teams
Diagnose the causes
Provide remedies, prove
that the remedies areeffective
Deal with resistance tochange
Control to hold the gains
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Sporadic shift/Assignable cause
Quality Control
Quality Control
Quality Improvement
Dr. JuranTime
Good
Bad
Per
forman
ce
Q Control & Q ImprovementQ Control & Q Improvement
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Reasons for variation in processReasons for variation in process
5M5M
2. The Machine
is subject to temperaturevariation, clearance in guides and
bearings (wear), and also to vibration,which can all lead to deviations from thetarget.
3. MaterialComposition, hardness,
tensions, porosity, bubbles,conditioning (water content).
4. The Method
ofmachining / processing
parts can be unsuitable.
5. Mother Nature
(the
environment)can contribute to measurementvariation, e.g. due to insufficient
lighting, dust/dirt, vibration.
As a rule, some (possibly all) of these groups together cause the
random variation
in production.
1. Man. According to the rule 80/20, mostproblems are caused by the process (80%).
Man Machine Material Method MotherNature
Variation
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Process Control System
Men
Machine
MaterialMethod
Environment
Process Product /Service Customer
Identify changing need
And ExpectationOutputInput
Statistical
Method
Voice of Customer
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7 QC TOOLS
1 CHECK SHEET
2 PARETO DIAGRAM
3 CAUSE & EFFECT DIAGRAM
4 GRAPHS & CHARTS
5 HISTOGRAMS
6 CONTROL CHART
7 SCATTER DIAGRAM * * ** * *
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Ishikawa / cause and effectIshikawa / cause and effect
LowMilageIn my
bike
Machine
environmentMethod
Man
Improper accelerator
Less driving skill Improper lubrication
Poor road quality
Poor quality of fuelImproperadherance to
serviceschedulw
Variation in service
Over loading
Poor Qua;lity of air
Traffic condition improper
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LTL M UTL
T
LTL M UTL
TWhich is the betterWhich is the better
process?process?
Who is the better marksman?Who is the better marksman?
LSL USL LSL USL
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LTL M UTL
T
Who is the better marksman?Who is the better marksman?
LSL USL
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2020
Machine and Process CapabilityMachine and Process Capability
Cause and Effects Diagram (Fishbone, Ishikawa)Cause and Effects Diagram (Fishbone, Ishikawa)
Process resultProduct characteristic
Man Machine
Mother
Nature
MethodMaterial
Staff
Shift
Speed
Feed rate
Tool
Cycle time
Coolant flow and temp.
Pressures
Current (welding)
Power
Warm-uptime
Process flow
Pre-machining
Roughmaterial
Supplier
Batch
Roomtemp.
HumidityAir pressure
Unusual
events
Shock/Vibration
Location
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Cp =USL - LSL
6
Cpk=Near Spec Limit - Mean
3
LSL USL6
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2222
Machine and Process CapabilityMachine and Process CapabilityCapability IndicesCapability Indices
LSL USL
Process spread6 * s
Tolerance
Mean value
Tolerance
Cp = -----------------------------6 * s
Minimum value of:
USL Mean value
Cpk = -----------------------------
3 * s
and
Mean value LSL
Cpk = -----------------------------3 * s
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LSL USL
Process Width
6 Cp
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Cpk andCpk anddefect ratesdefect rates
Capability IndicesCapability Indices
0
5
10
15
20
25
25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
Merkmalswert
rel.Hu
figkeitin%25,00
30,00
35,00
40,00
45,00
0 50 100 150 200
Messwert Nr.
Merkmalswert
Cp 0.82Cpk 0.48
ppm 77105
% 7.7105
Not centered
Too much variation
Process not capable
Me
asuredValue
Value No.
Measured Value
Relativefrequencyin%
USLLSL
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LSL USL
Process Width
6 Cp >1
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LSL USL
Process Width
6
Cp>>1
Six Sigma QualitySix Sigma Quality
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Machine and Process CapabilityMachine and Process Capability
Capability IndicesCapability Indices
0
5
10
15
20
25
30
35
25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
Merkmalswert
rel.Hufigkeitin%25,00
30,00
35,00
40,00
45,00
0 50 100 150 200
Messwert Nr.
Merkmalswert
Cp 1.41Cpk 1.41
ppm 54
% 0.0054
Centered
Variation relatively small
Process capable
M
easuredValue
Value No.
Measured Value
Relativefrequencyin%
LSLLSL
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Is 99.9% Quality ok for you ?Is 99.9% Quality ok for you ?
What does 99.9% means to our daily life?What does 99.9% means to our daily life?
500 defective surgeries weekly500 defective surgeries weekly
20 000 wrong prescriptions yearly20 000 wrong prescriptions yearly22 000 checks hourly withdrawn from22 000 checks hourly withdrawn from
wrong bank accountwrong bank account
20 non tightened wheel nuts daily20 non tightened wheel nuts daily
80 failures of each car produced80 failures of each car produced
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Six Sigma
Most recent trend in the world of Quality
is Six Sigma developed by Mikel Harry
of USA.
Six Sigma claims to develop direct linkingbetween costumer complain reduction and
bottom line of Business.Implemented by Motorola, ABB,Allied Signals, GE, Wipro
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Six Sigma as a GoalSix Sigma as a Goal
PPM (withPPM (with ++ 1.5 s1.5 s
process shift)process shift)CpCp
22 3,08,5373,08,537
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Six Sigma as a BenchmarkSix Sigma as a BenchmarkSigmSigm
aa
SpellingSpelling TransformerTransformer
Mfg.Mfg.
Filling a PurchaseFilling a Purchase
OrderOrder
33 1.5 misspelled1.5 misspelled
words/page inwords/page in
a booka book
6680766807
defects/milliondefects/million
itemsitems
6680766807 incorrect orincorrect orunreadableunreadable
entries/million boxes toentries/million boxes tobe filledbe filled
44 1 misspelled1 misspelled
words/30words/30
pagespages
6210 defects /6210 defects /
million itemmillion item
62106210 incorrect orincorrect orunreadable entries /unreadable entries /
million boxes to bemillion boxes to befilledfilled
55 1 misspelled1 misspelled
word in a set ofword in a set ofencyclopediaencyclopedia
233 defects /233 defects /
million itemmillion item
233233 incorrect orincorrect or
unreadable entries /unreadable entries /million boxes to bemillion boxes to be
filledfilled
66 1 misspelled word1 misspelled wordin all of the bookin all of the bookcontained in acontained in a
small librarsmall librar
3.4 defects /3.4 defects /
million itemmillion item3.43.4 incorrect orincorrect or
unreadable entries /unreadable entries /
million boxes to bemillion boxes to be
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But thats not the end of the road of Quality
the journey of Quality is endless !
We have miles to go to reach the destination
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