Notes SPC - Nirma

8/8/2019 Notes SPC - Nirma

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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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1414

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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2828

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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