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TPM ManualTPM ManualChapter 7Chapter 7

QualityQuality--HozenHozen(Quality Maintenance)(Quality Maintenance)

JIPMJIPM--Solutions Co. Ltd.Solutions Co. Ltd.

Copyright 2010 JIPM-Solutions

The Definition of QualityThe Definition of Quality--Hozen (Quality Maintenance) Hozen (Quality Maintenance)

7 - 1

Definition Action

Establish zero-defect conditions in order to create equipment and processes that do not produce any quality defects

Establish Conditions

Check and measure those conditions periodically Daily Checks / Periodic Checks

Prevent quality defects by maintaining those conditions within a standard range of values

Preventive Quality-Hozen

Predict the possibility of quality defects by monitoring trends in the measured values

Trend Monitoring / Predictive Maintenance

Take preventive action Preventive Action


An illustration of The Definition of QualityAn illustration of The Definition of Quality--Hozen Hozen

Identify the 4-M conditions affecting quality and specify their control limits

Establish conditions

Condition BCondition CCondition D

Condition X

Monitor the state ofdeterioration, and maintain zero defects by taking preventive action

Condition Control

Condition A

Standard value

(4) Predict Defects

(2) Daily / Periodic Checks

(5) PreventiveAction

(Trend Monitoring)

(1) Establish Conditions and Standard Values (Establish Conditions)

Year / Month

(3) Prevent Deterioration of(Rate of deterioration)

7 - 2


The Basic Approach to QualityThe Basic Approach to Quality--Hozen Hozen

Develop sustainmentcapabilities

(the ability to spotabnormalities in thecausal system andrectify them swiftly

and accurately)

Men/WomenMaterials Machinery Methods

Sources of Quality Defects

Source zero-defect materials

Source zero-defect equipment

Find zero-defectmethods

Source zero-defect materials

Improve equipmentto zero-defect level

Improve methodsto zero-defect level

AutonomousMaintenance

Skills training

Quality Assurance

EquipmentManagement

Establish zero-defect conditions

for equipment


for processing

Condition control to preventoccurrence of defects

Zero quality defects

P-M Analysis

Control points

Controls (forchecking effects)

Checks (forchecking causes)

Reactivemanagement

1) Action is too late2) Action is badly timed

＋＋

Spot abnormalities

Deal withabnormalities andrestore required

conditions

Sustain requiredconditions

Create zero-defect materials

＋

＋

Create zero-defect equipment

Create zero-defect methods

Develop highly-competent operators expert in handing their equipment and work processes

Find out how quality characteristics relate to material properties, equipment precision and processing conditions


for materials

Preventiveaction


for equipment

7 - 3


The 4 Ms The 4 Ms –– The Determinants of QualityThe Determinants of Quality

Production standards

Standardisation

Process

Processed article

Quality Assurance

Inspection Inspectionstandards

MeasurementAdjustment

Training,observance ofwork standards

Establishoptimal

conditions

MachineryProcessing equipment

Jigs and toolsMeasuring instruments

•Work standards•Checking standards

Feedback

Feedback

MaterialsRaw materialsMaterials from previous process

MethodsProcess conditionsWork methodsMeasurementtechniques

Men / WomenSkillsMoraleEnvironment

Impr

ovin

g qu

ality

Sust

aini

ng q

ualit

y

7 - 4


QualityQuality--Hozen and the other TPM pillars Hozen and the other TPM pillars

＋

7 - 5

Quality Maintenance

Establish zero-defectcondition

(technical issues)decide rules rigorously

Maintain zero-defectconditions

(management issues)- observe rules strictly

Achieve and zero defects

Raising Improvement skills

Predict and prevent failures and defects

MP Design and robust design

Training &Education

•Revealing efficiency losses•Restoration•Pursuing excellence•Eliminating minor flaws•Turning adjustment into condition-setting•Identifying necessary skills

•P-M Analysis•Habit of thinking logically•IE (Industrial Engineering) techniques•The 7 QC tools•Quality engineering (design of experiments)

Raising analytical ability

•Detect deterioration•Measure deterioration•Restore equipment•Prevent deterioration

•Diagnostic techniques•Condition-based monitoring•Scheduled checks and overhauls

•Design zero-failure, zero-defect equipment•Vertical start-up•Design for manufacturability

Kobetsu-Kaizen(Focused Improvement)

Jishu-HozenAutonomous Maintenance

Kobetsu-KaizenEffective Maintenance

EarlyManagement

The 7 steps of Autonomous Maintenance

Develop operators expert in equipment,products and processes


The Evolution of QualityThe Evolution of Quality--Hozen Hozen

7 - 6 - a

1. QM at Fujikoshi1 Check quality standards

and quality characteristics

2 Check quality defect phenomena

3 Determine equipment to be managed

4 Identify equipment functions and structure, processing conditions and setup procedures

5 Investigate state of equipment and restore

6 Do P-M Analysis7 Establish defect causes8 Optimise settings,

processing conditions and setup procedures

9 Expose flaws10 Restore or improve11 Check results12 Establish conditions that

allow good product to be achieved

13 Consolidate checking methods

14 Determine standard values

15 Create Quality-Hozen Matrix

16 Incorporate into checking standards

17 Monitor trends and confirm results

2. QM Procedure from TPM Instructor Course (this manual)1 Verify the existing

situationConfirm quality standards and characteristics

valuesCreate flow diagram of individual processes

for building in qualityInvestigate defect situation and phenomena,

and stratify2 Investigate the

processes where defects occur

Draw up QA matrix

3 Investigate and analyse 3M conditions

Investigate 3M conditions in each processIdentify deficiencies through on-site

investigation4 Plan action to

correct deficiencies

Create Deficiencies Chart and identify countermeasures

Verify state of equipment, and restore / improve it

5 Analyse situations where the conditions for building in quality are unclear

Analyse situations where the conditions for building in quality are unclear

Experiment to find optimal conditionsEvaluate

6 Eliminate flaws in 3M conditions

Expose flaws in 3M conditionsCarry out improvementsEvaluate results

7 Finalise 3M conditions

Establish 3M conditions that allow goodproduct to be achieved

8 Consolidatechecking methods

Find ways to consolidate and fix the checking methods, and carry out improvements

9 Determine standard values for checks

Determine standard values for checksCreate QM matrixIncrease reliability of checks, simplify them,

and reduce number of people involved10 Revise standards

and monitortrends

Revise materials standards, checking standards and work standards

Identify Q components so that standardsare keptMonitor trends and confirm results

3. QM at Nissan1 Identify Existing Situation

2 Eliminate Deficiencies

3 Analyse Causes of Chronic Defects

4 Eradicate Causes of Chronic Defects

5 Establish Zero-Defect Conditions

6 Maintain Zero-Defect Conditions

7 Improve Zero-Defect Conditions

Carry out checks based on check standards

Monitor trends

Maintain Conditions

7

Consolidate checksRevise check intervalsImprove checking methods

Improve Conditions

6

Revise QM matrixRevise standards


5

Thoroughly investigate all causes

Restore and improveCheck results

Eradicate Causes

4

Analyse causesRevise the ideal conditions (standard values)

AnalyseCauses

3

Restore to current optimal stateheck results

Restore2

Investigate quality situationIdentify rules and proceduresAssess compliance

Identify Existing Situation

14. The Figure-of-Eight Method


The Evolution of QualityThe Evolution of Quality--Hozen Hozen

The History of Quality-Hozen

1984: Fujikoshi wins TPM Award; a particular highlight is its development of QM

1986: JIPM publishes Fujikoshi no TPM (‘TPM at Fujikoshi’)

1991: Nissan Motor Corp.’s Tochigi Plant wins Special TPM Award

1993: TPM Instructor Course manual is revised

1993: JIPM publishes Nissan Jidosha no TPM (‘TPM at Nissan Motor Corp.’)

1997: JIPM publishes Hinshitsu Hozen Hachi no Ji Tenkaiho (’The Figure-of-Eight Method forQuality-Hozen ’)

2003: TPM Instructor Course manual is again revised and updated

2003: JIPM publishes Ryohin 100% no Hinshitsu Hozen (‘Quality-Hozen for Perfect Product’)

The award of the TPM Prize to Fujikoshi and the publication of ‘TPM at Fujikoshi’ were the events that triggered the development of Quality-Hozen . The methodology has become firmly established and is continually being enhanced through the efforts of the JIPM to inform industry about it, and the research and practical application carried out by individual companies.

Sustain Improve36 4

5

7

1 2

7 - 6 - b


Overview of the FigureOverview of the Figure--ofof--Eight Method for QualityEight Method for Quality--Hozen Hozen

Sustain(Observe rules and procedures rigorously)

Improve(Tighten up existing rules and procedures, and replace any missing ones)


1-1 Investigate quality situation1-2 Identify rules and procedures1-2 Assess compliance

Restore

2-1 Restore2-2 Check results

AnalyseCauses

3-1 Analyse causes3-2 Revise standards

Eradicate Causes

Investigate causesRestore and improveCheck results


5-1 Revise QM Matrix5-2 Revise standards

Maintain Conditions

• Perform checks• Monitor trends(Revise the rules to ensure

they are observable)

Improve Conditions

• Reduce number• Extend intervals• Reduce times(Make them easier to observe)

1 2

3 4

5

6 7

Check

7 - 7


Overview of the FigureOverview of the Figure--ofof--Eight Method for QualityEight Method for Quality--Hozen Hozen （（Step1,2Step1,2））





Restore


AnalyseCauses


Eradicate Causes




Maintain Conditions



Improve Conditions


1 2

3 4

5

6 7

Check

7 - 8


Actions Taken After Checking ResultsActions Taken After Checking Results

12

3

[Type 1] [Type 2] [Type 3]

Determine conditions Revise sustainment system Sustain and Improve

7 6

5

4

12

5

74

12

5

74

3 6 36

7 - 9


Overview of the FigureOverview of the Figure--ofof--Eight Method for QualityEight Method for Quality--Hozen Hozen （（Step3,4,5Step3,4,5））





Restore


AnalyseCauses


Eradicate Causes




Maintain Conditions



Improve Conditions


1 2

3 4

5

6 7

Check

7 - 10


Overview of the FigureOverview of the Figure--ofof--Eight Method for QualityEight Method for Quality--Hozen Hozen （（Step6,7Step6,7））





Restore


AnalyseCauses


Eradicate Causes




Maintain Conditions



Improve Conditions


1 2

3 4

5

6 7

Check

7 - 11


Draw up orthogonal arrayQuality Engineering

The figure of Eight Method for QualityThe figure of Eight Method for Quality--HozenHozen

4. Eradicate causes

*

Sustain Improve(Tighten up existing rules andprocedures, and replace any missing ones)

1. Identify existingsituation

2. Restore

3. Analyse causes

5. Establish conditions

7.

1-(1)Investigate quality situation• Identify quality characteristics• Identify qualitycharacteristic values

• Stratify defect phenomena

1-(2)Identify rules and procedures

1-(3)Assess

compliance

A B C D

QM matrix

A B C D

2-(1)Restore

3-(2)Revise standards

P-M Analysis table (1) P-M Analysis table (2)

Perform experiments

Do statistical processing

Test results

Revise

Standards

A B C D E F Improvement 1Improvement 2Improvement 3Improvement 4PM Analysis

A B C D

Improvementresults

QM matrix

6. Improve conditions

1 2 3 4 5 6 7 8 9 10 11 12Date

Revise checksheet

7-(2)Monitor trends

7-(1)Perform checks

1 2 3 4 5 6 7 8 9 10

Standard value

Trend control graph

Maintain conditions

(Observe rules and procedures rigorously)

5-(2)Revisestandards 5-(1)

Revise QM Matrix

3-(1)Analyse causes6-(1)(2)(3)

• Reduce number• Extend intervals• Reduce times(Make them easierto observe)

2-(2)Checkresults

7 - 12

Standards

Perform tests to establish optimal values

[The 4 Kaizen Principles:]EliminateCombine RearrangeSimplify

4-(1)(2)(3)• Investigate causes• Restore and improve• Check results

Result

Counterm

easuresIdentificationInvestigationStandardsItem

s forcheck

Parts

86 75

Com

ponents

Assem

bly parts

Unit Level

Phenomenon

Explanation by A

BC

D

Diagram

1 2 3 4

3

3+6

6

Insp

ectio

nIte

ms


Results of Investigating Quality SituationResults of Investigating Quality Situation

100

99

98

97

96

0

Qua

lity

Rat

e

Year / Month

%2.5

2.0

1.5

1.0

0.5

0

100

80

60

40

20

0

Def

ect R

ate

Col

our d

ensi

ty

defe

cts

Run

s

Cur

rent

pas

sage

de

fect

s

Oth

er d

efec

ts

3

2

1

0

Def

ect R

ate

Year / Month

Colour density defects

% %

(1) Quality Rate (2) Pareto diagram (3) Stratified bar chart

[Monitoring overall quality rate] [Stratifying defect rates] [Monitoring individual defect rates]

36 4

5

7

1 2

Case1

7 - 13


Process

Racking

Electrolysis

Degreasing

Etching

Neutralisation

Electrolytic pigmentation

H2SO4

NaOH

H2SO4

NiSO4 Ni

Remove oil and grease from Al-Mg-

Si alloy

Process Function

Dissolve surface of aluminium (to

eliminate grease and scratches)

Remove smut (Mg, Si)

Form alumite

Deposit nickel (pigment)

Principal conditions

• Sulphuric acid concentration• Temperature• Immersion time

• Caustic soda concentration• Temperature• Immersion time

• Sulphuric acid concentration• Immersion time

• Sulphuric acid concentration• Temperature• Electrolysis

• Quantity of nickel metal salts deposited

• Temperature• Immersion time

Function of Surface Treatment ProcessFunction of Surface Treatment Process

H2SO4

36 4

5

7

1 2Case1

7 - 14


QM Matrix for Surface Treatment ProcessQM Matrix for Surface Treatment Process

36 4

5

7

1 2

Case1

7 - 15

Quality CharacteristicsProcess Control Item Standard value Interval Person

responsible Runs Colour hue

Colour density

Water temperature XX ± 2 ﾟC O XpH 3.8 – 4.2 1/shift Manufacturing O △

Circulation rate 20% open Daily Maintenance -Water supply rate X m3/h Weekly Technical O OImmersion time X’ XX” Monthly O △

NiSO4 concentration XX±10 g/l Annually O OLiquid temperature XX±1ﾟC ± O O

pH 4.7 – 5.3 O OAl concentration XX ppm max. O OCirculation rate 100% open -

Current density XX A/m3 O O OP process XX second O O △

Switchover XX second O O OC process XX second O O △

NiSO4 concentration XX g/l max. O O -Circulation rate Open : 50% -Surface height 461 mm O -

Water supply rate X m3/h O O

No. 14Pigmen-

tationProcess

Process conditions

No. 13Pigmen-

tationProcess

No.9 Wash

(Water)

Compliance


Change in Water Temperature and Colour Density VariationChange in Water Temperature and Colour Density Variation

Col

our d

ensi

ty

Dark

10

8

6

4

Wat

er te

mpe

ratu

re

Col

our d

ensi

ty

Light

Dark

Light

10

8

6

4

Wat

er te

mpe

ratu

re

Before Improvement After Improvement

Conditions changed by operator

36 4

5

7

1 2

Case1

7 - 16

02468

10121416182022

Jan

Feb Mar AprMay Ju

n Jul

Aug Sep OctNov Dec

Colour density

Water temperature

02468

10121416182022

Jan

Feb Mar AprMay Ju

n Jul

Aug Sep OctNov Dec

Colour density

Watertemperature


Change to More Tolerant ConditionsChange to More Tolerant Conditions

t : 15 sec.

L:8.6

Before Improvement

(current density XX A/m2)

Col

our

Dark

Light

After Improvement

(current density YY A/m2)

Col

our

Dark

Light

second

36 4

5

7

1 2

Case1

7 - 17

20 25 30 35 40 4520 25 30 35 40 45

second

L:4.8

t : 15 sec.


Improvement ResultsImprovement Results

Trend in Defect Rates36 4

5

7

1 2

Case1

7 - 18

0

1

2

3

4

Before After

Def

ect R

ate →

Other defectsCurrent passage defectsRunsColour density defects

%


Colour Density Control MechanismColour Density Control Mechanism

Electrolysis

Alumite LayerBarrier Layer

Post-Electrolysis Wash

(4-stage)

Pigmentation

(Pre-treatment)

(Full current passage)

When anodic oxidation is carried out in a 10% sulphuric acid electrolyte, the film properties change and become irregular, and the colour of the aluminium substrate itself changes, as a result of heat generation and voltage in the vicinity of the barrier layer

Dissolved Al becomes hydrated, forming an Al(OH)4 gel, if the water pH is too high or the immersion time too long (i.e.the alumite turns into boehmite)

Passing current through the pigment layer enlarges the barrier layer and improves the pigmentation coverage

Ni is deposited and the colour density is changed by controlling the time for which current is passed, in accordance with Faraday’s Law:

amount of Ni deposited = current (A) x time (s)

Pigmentation

36 4

5

7

1 2

Case1

H2SO4H2SO4

H2SO4

H2SO4

H2SO4 H2SO4

Ni Ni Ni Ni NiNi Ni Ni Ni

Ni Ni Ni Ni NiNi Ni Ni Ni

7 - 19


PP--M analysis TableM analysis Table

36 4

5

7

1 2

Case1

7 - 20

Standard

Dark

Light

Phenomenon Physical Analysis Contributing Conditions

4-M Correlations (Primary)

4-M Correlations (Secondary)

Investigation results

1-1-1 pH variation X O1-1-2 Liquid temperature variation X O

1-1-3 Immersion time variation

1-1-4 Variation in quality of liquid in tank X O

2-1-1 Variation in P treatment time X2-1-2 Variation in P treatment time X

2-2-1 Soiling of clamping jig O2-2-2 Soiling of electrical connector

to beam O

2-2-3 Looseness of V-groove attachment bolt O

2-2-4 Corrosion of beam bracket O

2-2-5 Soiling of electrical connector to pigmentation layer O

2-2-6 Anode condition O2-3-1 Difference in material O2-3-2 Variation in heat-treatment

condition X

2-3 The electrical conductivity of the Al sections varies

2-2 There are defects in the current path

Anodic oxidation film

Level of deposition of metal salts

2-1 Inappropriate control of current

2. Variation in flow of current into material

1. The activity of the porous anodic oxidation film varies during pigmentation.

1-1 Post-electrolysis wash conditions are unsuitable.

Sometimes the colour is darker or lighter than standard

The amount ( C ) of nickel oxide (B) deposited in the porous anodic oxidation film (A) varies (D)


Increase in Precision of Current Passage ControlIncrease in Precision of Current Passage Control

Power supply

Signal

Output Output

Signal

Setting Error: ±2sec.

Setting Error: ±0.3 sec.

<Before improvement> <After improvement>

36 4

5

7

1 2

Case1

7 - 21

XX calculation

XX command

Reagent controlScan time

2 sec.

Current Passage

control

Process computer

XX calculation

XX command

Reagent controlScan time

2 sec.

Current Passage

control

Process computer

Power supply

Current passage

table


Other defectCurrent Passage defectsRunsColour density defect

Trend in Defect RatesTrend in Defect Rates

Before Improvement

After completion of Step2

After completion of Step4

Def

ect R

ate

→

36 4

5

7

1 2

Case1

7 - 22

0

1

2

3

4%

0

1

2

3

4%

Colour density defect


Trend Monitoring at No. 10 Water Washing BathTrend Monitoring at No. 10 Water Washing Bath

36 4

5

7

1 2

Case1

Date

7 - 23

3.4

3.5

3.6

3.7

3.8

7/1 5 10 15 20 25

pH


Standards for Evaluating Level of Control of Rules and ProcedureStandards for Evaluating Level of Control of Rules and Procedures s

Control Level

Description of Control Level

Preventing defects from occurring

Preventing defects from being passed on

A

Cannot create defects

Error-proofing of causes

-The equipment controls the good-product conditions, and if the conditions are not satisfied, then the equipment will not operate

-Defects do not occur-Zero possibility of passing on defects

B

Cannot pass on defects

Error-proofing of results

-Individual defects are identified as and when they occur

-There is a system for preventing defective product from being passed on. Defective product halted by equipment and process.

C

Does not create or pass on defects

Operator checks

-Operators control the good-product conditions. If the conditions are not met, then they make adjustments.-There is a possibility of a series of defects occurring

-To prevent defective product from being passed on, operators check the quality and halt any defective products.-High chance of passing on defects

DOut of control No control

method established

-Defects cannot be prevented -If a defect occurs, it is always passed on

36 4

5

7

1 2

Case2

7 - 24


Procedure for Developing QualityProcedure for Developing Quality--Hozen in Manual Work Processes Hozen in Manual Work Processes

1-(3) Identify work conditions

1-(4) Create Process QA Rate EvaluationTable

2-(1) Assess control level1-(1) Clarify qualitycharacteristics

2-(2) Evaluate QA level

Prevention ofoccurrence

Preventing ofpassing on

2-(3) Calculate QA rate for process

Prevention ofoccurrence

Preventing ofpassing on

a b c d a b c d

1-(2) Investigate defectsituation

% In-processdefects

ppm Passed-on defects

3. Investigate relationships between QA level and defect situation

4. Establish targets

5. Propose improvements and implement them (right-first-time assurance to prevent occurrence of defects)

a b c d a b c d

% In-processdefects

ppm Passed-on defects

6. Check results and evaluate

+=

7. Consolidate gains and sustain

Improvementtopics

Conditions

Control level

ProcessAssurance

Level

QualityCharacteristics

Re-assessassurance rate

Process QA rateevaluation table

36 4

5

7

1 2

Case2

7 - 25


Quality Assurance Rate in an Assembly Process Quality Assurance Rate in an Assembly Process

High Low

(1) Process quality assurance rate = No. of characteristics in grey shaded area X 100

Total no. of characteristics

High

Low

(2) The symbol indicates the thrust of activities for improving the process QA rate

Countermeasures already in equipment, e.g. error-proofing

Warning functions exist

Depends on worker's skills

A B C

Function1

Function2

Function3

Function4

Level (cannot make / cannot pass on)

Impo

rtanc

e of

aut

omat

ic

trans

mis

sion

uni

t fun

ctio

n36 4

5

7

1 2

Case3

7 - 26


Trend in Rate of Assembly Defects Trend in Rate of Assembly Defects

Defects passed on to later processes

Def

ect R

ate

(ppm)

9 10 11 12 1 2(year/month)

△△

△△

0

36 4

5

7

1 2

Case3

7 - 27


QA Matrix (Process QA Rate Evaluation Table)QA Matrix (Process QA Rate Evaluation Table)

36 4

5

7

1 2

Case3

7 -28

Assurance (Check ) Process

1 2 5 6 7 20

Importance

FEMA

Actual D

eficiency

C

A

B

A

BBBAAA

O

O

O

O

O

OO

Knock pins Part missing Insertion Defect A A Error Proofed

O-ring Missing C Needs Action

E-ring Missing B Needs Action7 Parking Assembly

Ball Missing A Error ProofedRing Insertion B Needs Action

6 Shaft AssemblyPin Missing B

5 Spring Assembly Fastening Defect C Needs Action

2 Support Assembly Fastening Defect A A Error Proofed

Lever pins Part missing Insertion Defect A B A Error Proofed1

Press Fitting

One-way valve Assembled B B A Test Pattern Changed

Performance

test

Shaft A

ssembly

Parking A

ssembly

Press Fitting

Support A

ssembly

SP Assem

bly

Overall Verdict

RemarksName of ProcessActual /EnvisagedDeficiencies


Improving OperatorImproving Operator--Dependent Assurance Modes 1Dependent Assurance Modes 1

36 4

5

7

1 2

Case3

7 - 29

Before Improvement After ImprovementItem

Error-proofing introduced to detect missing O-ring

Error-proofing introduced to prevent missing components in control valve assembly

O-rings installed here

O-rings

Sensor for confirming jig installationO-rings are installed in the three grooves on the shaft. It was envisaged that one or more of the O-rings might be omitted when doing this task.

O-ring identification

sensor

An error-proofing device was installed, consisting of a detector used after installation to check that all the O-rings are in place.

Beep!

11 different components are used in assembling the control valve; the operator occasionally missed a component and had to redo the task..

An error-proofing device was installed, using sensors fitted to the component box and assembly tools. If one of the components or tools has not been used, then the hydraulic tool for fastening the last bolt is prevented from operating.

Missing components

Woops!

Missing components


Improving OperatorImproving Operator--Dependent Assurance Modes 2Dependent Assurance Modes 2

36 4

5

7

1 2

Case3

7 - 30

Before ImprovementItem

Error-proofing introduced to prevent missing springs

Error-proofing introduced to prevent omission of bearing races

In the automatic assembly device used in the packing process, 12 springs are supplied by a parts feeder. At the next station, components are installed on top of these springs. The team were concerned that springs might be omitted.

Error-proofing using contact sensors was introduced, to check that all the springs were in place after the supply step. If a spring is missing, an alarm sounds and the machine is halted.

It was imagined that, when fitting the bearing races, some might be left out, or the wrong ones used.

An automatic feed device was installed to supply the bearing races, one by one, in the correct order. Each time one is taken out, a photocell detects it, and the device delivers the next one to be fitted. This system prevents bearing races from being missed out, or the wrong ones being used.

Which one’s next?Pneumatic cylinder

supplies bearing races in correct order

Beep!

Detect presence of

springsParts feeder moves down

Moves downSupplies

spring

Moves up after

supplying spring

After Improvement

Detector senses when bearing race has been taken out


Confirmation of Results Confirmation of Results

0 9 10 11 12 1 2 3 4 5 6 7 8 9 10

0

85

90

95

100(%)

(Month)

Ass

uran

ce L

evel

Def

ect R

ate

～

～

Process quality assurance

Defects passedon to later stages

(ppm)

36 4

5

7

1 2

Case3

7 - 31

Z

Y

X

95.3


Using ParetoUsing Pareto--diagram Stratification to Observe the diagram Stratification to Observe the GenbutsuGenbutsu

Why?

Too Many Process Defects

Why?

Too Many Coil Defects

Too Many VoltageResistance Defects Windings are Too Thick

Bobbin

Coil Case

Too Many CoilDefects

Why? Observe‘Genbutsu’

Too Many VoltageResistance Defects

PM Analysis Step 1

7 - 32


Understanding the Contact point and the Principles of ProcessingUnderstanding the Contact point and the Principles of Processing

2

3

4

Copper Wire

Flyer

Bobbin

Contact Diagram

[ Principles and Parameters ]

PM Analysis Step 2

7 - 33

1

A fixed bobbin (1) is wound with copper wire (4) paid out from a rotating flyer (2) that moves axially (3).


Physical Analysis Using ABCD Description Physical Analysis Using ABCD Description

Draw Diagram To Aid Thinking Process

Describe in ABCD Format

Copper Wire (B)

Pitch (C)

Small (D)

(Varies)

•A fixed bobbin (A)

•Is wound withcopper wire (B)

•Paid out from arotating flyer andpitch (C)

•Is too small (D)(varies)

Bobbin (A)

PM Analysis Step 2

7 - 34


Simple Mechanism Diagram (Compact Turntable Winder)Simple Mechanism Diagram (Compact Turntable Winder)PM Analysis Step 3

7 - 35

Tensioning Arm

Cooper Wire

Tensioning PulleyTensioner

Drive UnitGuide rod

Splined Shaft

Indexing Table

Bobbin

V Belt

Flyer

DC Motor

Gearwheel

Winder

Guide rod

Ball thread

Tensioning Lever

Shock Absorber

Timing Belt

DC Motor

DC Motor

Cooper Wire

Timing Belt


Unit Function Investigation Table Unit Function Investigation Table

FunctionsFunctional

Unit Necessary Desirable

Tensioner Supply copper wire

Maintain constant tension Yes Tension varies

Winder Rotate flyer Rotate at constant speed Yes Rotation speed varies

Drive unit Move flyer axially Move at constant speed Yes Speed varies

Indexing table Supply bobbins Supply to fixed point Yes Bobbin moves

Poor materials

Number of contributing conditions = total number of functional units +2 Unsatisfactory method

Affects Physical

Quantity?

Contributing conditions

PM Analysis Step 3

7 - 36


PP--M Analysis TableM Analysis Table

Phenomenon Physical Analysis

Contributing Conditions

4-M Correlations(Primary)

4-M Correlations (Secondary)

1-1-1. Playing spring fixing block1-1-2. Block fixing bolts loose1-1-3. Springs worn out1-1-4. Play in shock-absorber plate1-1-5. Shock-absorber spring worn out1-1-6. Shock-absorber spring adjustment bolts loose1-1-7. Play in tension lever fixing1-1-8. Play in tension arm fixing1-2-1. Wire not wound correctly onto supply wheel1-2-2. tension rubbers worn1-2-3. Rubber tension adjusting bolts loose…..2-1. Variation in rotational

speed of motor …..2-2-1. Timing belt loose worn2-2-2. Timing pulley worn2-2-3. Pulley loose2-3-1. Ball screw worn2-3-2. Block fixing bolts loose2-3-3. Guide bar bolts loose2-3-4. Sliding bearings worn or loose

(remainder omitted)

2-3. Variation in speed of movement of flyer

2.The lateral speed varies

2-2. Variation in rotational speed of ball screw

1-2. Set tension cannot be maintained

The Pitch[C] of a copper wire[B] wound about a

bobbin[A] shows variation[D]

The coil windings are

too thick

The Pitch[C] of a copper

wire[B] wound about a bobbin[A]

shows variation [D]

1-1. Tension setting varies

1.The required tension varies

Bobbin

Pitch

Copper wire

PM Analysis Step 4

7 - 37


Investigation Results and Deficiencies Identified Investigation Results and Deficiencies Identified

Location of Check

Item to be Checked

Measurement Method Tolerances Measured

value Corrective Action Result

Tensioner Variation in tension Tensometer 510–580 g 120–580 g

1. Redesign tensioner device2. Redesign all rollers3. Clean all guide holes

Kept within tolerances

WinderVariation in rotational speed

Tachometer ± 2% ± 0 OK

Drive unitVariation in speed of movement

Dial gauge

Variation in return point ± 0.05mm

0–0.32 mm

1. Adjust slack in timing belt2. Halt operation for 0.5 sec. at return point

Within 0.03 mm

(remainder omitted)

PM Analysis Step 5,6,7,8

7 - 38


Condition of Windings and Trend in Voltage Resistance Defects Condition of Windings and Trend in Voltage Resistance Defects After Improvement After Improvement

0

10

20

30

40

50

60

None of thewindings is too

thick. Gapbetween windings

and case ismaintained. N

umbe

r of D

efec

ts

( Month )

PM Analysis - result

7 - 39

Trailed on model winding machine

Extended to other winding machines


The Development of QualityThe Development of Quality--Hozen (a 10Hozen (a 10--step procedure)step procedure)

7 - 40 - a

・ Investigate 3-M conditions, using drawings, standards, manuals, etc.・ Work out what the 3-M conditions should be, on the basis of processing principles, equipment mechanisms/functions, etc.・ Do on-site investigation to establish 3-M conditions and highlight failures to maintain them

Investigate and analyse 3-Mconditions

3

・ Find relationships between individual processes and defect modes

Investigate processes where defects occur

2

Inve

stig

ate

and

Ana

lyse

(4) Set targets and make action plan

(3) Investigate defect situation and phenomena, and stratify

・ Identify equipment systems’ mechanisms, functions, processing principles, sequences, etc.

(2) Create flow diagram of individual processes that determine product quality

・ Specify the quality characteristics to be maintained(1) Confirm quality standards and characteristics

Verify existing situation

1

Prep

are

Impr

ove

Qua

lity

CommentsContentsStep

On this basis, draw up a QA matrix* Investigate individual processes where defect modes occur

(1) Investigate 3-M conditions in each process(2) Identify lapses in these conditions through on-site investigation

・ Understand circumstances in which a quality defect occurs in processing・ Stratify defect phenomena・ Identify individual processes giving rise to defect phenomena



7 – 40 - b

Finalise 3-M conditions7

Eliminate flaws in 3-Mconditions

6

Impl

emen

t Im

prov

emen

ts

Analyse situations where conditions for achieving good product are unclear

5

(1) Create Deficiencies Chart and identify countermeasures(2) Verify state of equipment, and restore/improve it

Plan action to correct deficiencies

4

Plan

Impr

ovem

ents

(1) Analyse situations where the conditions for building in quality are unclearExperiment to find optimum situation(2) Evaluate

(1) Expose flaws in 3-M conditions(2) Improve(3) Evaluate results

Establish conditions for the 3 Ms which allow good product to be achieved

・ Verify sustainment through Jishu-Hozen activities; investigate process conditions and setup methods; restore to fix deficiencies・ Improve equipment that does not meet equipment conditions

・ Return to principles and parameters of processing, and identify all relationships between quality characteristics and processing conditions / equipment precision・ If there are several problematic characteristics in the same equipment, then work out which part of the equipment affects which quality characteristic・ Use P-M Analysis, FMEA, design of experiments, etc. to pinpoint the relationships between defect causes and the 3 Ms; establish 3-M conditions for building in quality・ Set provisional tolerances (standards) for equipment precision and processing conditions, so that the quality characteristics stay in the standard range

・ Check/investigate 3 Ms according to 3-M conditions from analysis results・ Identify deficiencies, restore original state and improve・ If all checkpoints are within provisional tolerances, check that quality characteristics meet standard values



7 – 40 - c

Revise standards and monitor trends

10

Determine standard values for checks

9

・ Classify the checkpoints into static precision, dynamic precision and processing conditions; try to consolidate checks・ At the same time, do improvements to make checks quicker and easier

Find ways to consolidate and fix the checking methods, and carry out improvements

Consolidate checking methods

8

Stan

dard

ise

Sust

ain

Qua

lity

(1) Revise materials standards, checking standards and work standards(2) Display Q component tables so that standards are adhered to(3) Monitor trends and confirm results

(1) Determine standard values for checks(2) Create QM matrix(3) Increase reliability of checks, simplify and reduce number of people involved

・ Using methods such as vibration measurement, establish substitute characteristics for controlling the equipment precision tolerances (standard values) required to keep quality characteristics within standards・ Assign all checks apart from those needing special measuring equipment, or strip-down checks requiring skill/time, to the Operations Department・ Find and implement ways of increasing checking reliability, simplifying checks, and reducing number of personnel required

・ Managers must educate operators about the reasons why these checks are necessary, on the basis of the equipment mechanisms, structures and functions, and the processing principles・ Operators should add their own notes to checking manuals・ By monitoring trends, take preventive action before values exceed the standard ranges・ If any other quality problem arises, unrelated to the specified standard values, revise the standard values, items to be checked, and checking methods


QA Matrix

Investigate and analyse 3-M conditions

As current situation

List deficiencies

Aims1. Confirm quality characteristics (built in by process or equipment)2. Study and assess defects or complaints where quality characteristics are not satisfied3. Investigate individual processes where defect mode has occurred

Identify 3-M conditions that will produce zero defects in each individual process

Identify measures for combating deficienciesStudy carefully how these measures are actually to be implemented

3-M conditions are deficient

Deficiencies where conditions for achieving good product are hard to define

Cannot be consolidated

Revise Standards

Consolidate and fix

Establish 3-M conditions Checking standards

Work standards

Standards must be capable of being observed, and their

observance must be monitored

P-M Analysis

Revise 3-M conditions

Carrying Out QualityCarrying Out Quality--Hozen Hozen

Improve materials and methods

Kobetsu-Kaizen plan (analyse, experiment, evaluate)

Improve equipment

Deficiencies where conditions for achieving good product are hard to define

Improve materials and methods

Kobetsu-Kaizen plan (analyse, experiment, evaluate)

Improve equipment

Cannot be consolidated Consolidate and fix

Establish 3-M conditions

Revise 3-M conditions

7 - 41


Basic Approach to Consolidating ChecksBasic Approach to Consolidating Checks

Classify as fixed cause or variable cause

Identify checks via P-M Analysis

Identify items that affect quality

Fixed VariableImprove

Classify as static precision, dynamic precision, or processing condition

Static precision Dynamic precision Processing condition

Improve and consolidate to facilitate

checking

Leads to unacceptable dimensional precision, etc

Leads to unacceptable precision of visual appearance


checking

Consolidate checks by using substitute characteristics

Consolidate checks by using substitute characteristics

Fix by quantification and indexing

Fix by quantification and indexing

Establish static conditions

Establish static conditions

Establish conditions based on vibration level,

etc.

Establish conditions based on vibration level,

etc.Items that cannot be fixed in any way

Items that cannot be fixed in any way

ConsolidateConsolidate

Static precision Dynamic precision Processing condition


checking


checking

7 - 42


* Gap between bearing and shaft

Plan view of cylindrical grinder

Vibration measurement point

Investigate vibration levels and

roundness in similar models.

Correlation exists between vibration

level and roundness. Correlation

coefficient was 0.87, so looked for

regression line

Correlation between roundness and vibration

velocity

Max. vibration set to 2 mm/s

Why do some machines vibrate a lot and some only a

little?

Machines that vibrate a lot have a large gap between bearing and shaft

When bearing was adjusted, vibration velocity reduced, and roundness

improved

Bearings of heavily-vibrating machines

were adjusted to bring vibration

velocity below 2 mm/s

Measure vibration once a fortnight, and

monitor trendsAdjust bearing if vibration starts to approach 2 mm/s

Before adjustment

After adjustment

Freq

uenc

y

Roundness (μm)Comparison of frequency distribution of roundness before and after adjustment

Examples of Consolidating Checks by Vibration MonitoringExamples of Consolidating Checks by Vibration Monitoring

From regression line, vibration velocity must

be kept to 2 mm/s or less to keep roundness within 3 μm of standard.

7 - 43

X=1.6S=0.13

X=3.0S=0.22

1 2 3

Roundness Vibration

Before A

djustment

μm80 -

100

5.0μm

12.1 mm/s

After A

djustment

μm20 -

30

2.7μm

1.8 mm/s

Rou

ndne

ss

Vibration velocity (mm/s)2 4 6

6

4

32

(μm)

Relation between Roundness and Vibration after adjustment


Example of Check Consolidation in Chemical PlantExample of Check Consolidation in Chemical Plant

Check Possibility of Consolidation Consolidation

Materials

1 PVC slurry density30% max.

2 PVC slurry temp.70% max.

3 Feed water concentration

1 PVC slurry determined in previousstep; no direct relationship with contaminants in the feed stage, so no need for check here

2 Feed water standards adhered to

No checks required

Equipment

1 P11 –1, 2, 3, 4-D stuffing boxMust not overheat

2 P11 –1, 2, 3, 4-D stuffing boxWater injection 2l/min. at least

3 Water injection pump: min. pressure 5kg/cm2

1 P11 –1, 2, 3, 4-D stuffing box converted to self-flushing (does not require water injection). No overheating occurs, but priming is needed at start up and shutdown.

2 Check required

1 Consolidate checks so that water volumes injected at pump start up and shutdown are checked as part of standard operating procedures.

2 Check at start up and shutdown.

Methods (People)

1 Stuffing box overheating checkOnce / shift

2 Stuffing box water flowrate check3 Pump discharge pressure check

2 kg/cm2 minimum4 Pump current check Once / shift5 Water injection pump discharge

pressure check 5 kg/cm2 minimum

1 Water injection required at startup and shutdown, as in Equipment category.

2 Confirmation required atshutdownConfirmation of normal operation required

3 Check required

1 Same as Equipment category, so check to confirm water volume of 2l/min. at pump startup and shutdown

2 Check once per shift3 Check once per shift

11 Checks 5 Checks

7 - 44


Example of Quality Check Matrix Example (1)Example of Quality Check Matrix Example (1)

Quality characteristics

Part Item to be measured Standard value Measurement

intervalRoundness Cylindricality Surface

damage

AGrindstone spindle

Vibration Y mm/s or less Once / month ○

BWork spindle

Vibration Y mm/s or less Once / month ○

D Table Parallelism A μm or less Once / month ○

E Aux. guide Wear B mm or less At setup ○ ○

F Aux. guide Wear C mm or less At setup ○ ○

7 - 45


Example of Quality Check Matrix Example(2)Example of Quality Check Matrix Example(2)

7 – 46,47

Extrusion Machine Die Forming diePart RT

temp.Barrel Screw Temp. Outer

dia.Clearance Top die Bottom

dieClearance Cooling

water

Check PointTemp. Wear Wear Temp. Wear Thickness

differenceVacuum nozzle dia.

Vacuum nozzle dia.

Thickness difference

Flow rate

Temp.

Standard value185ºC± 3ºC

Dia.±0.3mm

Dia.±0.3mm

220ºC±3ºC

0.02mmmax.

1.13 mm ±0.03

1.0–0.2 max.

1.0–0.2 max.

1.55 ±0.03 15ºC ±2ºC

FrequencyOnce / day

Once / 6 mth.

At setup Once / day

At setup At setup At setup At setup At setup Once / cycle

Once / cycle

Bumpiness O O O O O O

Lustre O O

Shrinking O O

Quality

Characteristics Warping O O O O O

tpm manual chapter 7 quality-hozen - industristore.com · an illustration of the definition of...

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