Six Sigma Project - Brakes India - Wall Thickness Variation

8/10/2019 Six Sigma Project - Brakes India - Wall Thickness Variation

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6s Project

DefineMeasure & Analyze

ControlImprove


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Project Number SEL/QA/2006-001Plant SHOWA ENGG.LTD

Name of the Black Belt Mr.S.DORAISWAMY

Team Members Mr.C.SUKUMAR

Mr.D.PONNUVEL

Mr.V.VADIVELU

Mr.A.NANDHAKUMAR

Date of Start 03.07.2006

Six Sigma Project

6


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Caliper Housing

ApprovedComponent

RejectedComponent

Mounting hole less wall thickness


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Define Phase


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Phase 1- Problem Definition

Number of lines/presses/machines used for processing One Machine

Objective of the Project To Reduce this defect to Zero

Annual Savings in Rs. Lakhs if the defect is made zero and horizontally

deployed to other part numbers Rs.1,21,584

Response Variable / Attribute

Specification (if the response is variable)

PCD Dimension : 159.0 0.075 ,Wall thickness: 4.8 mm to 5.8 mm Is R&R study required

Yes / No

If R&R study is required, % R&R to tolerance 10%


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Problem Statement Pin hole less wall thickness (Up to 4.2 mm as against 4.8mm to 5.8mm)

Part number selected for study 29320155/56

Other similar part numbers having the problem

Nil Process stages where the Problem is detected

Opn No : 30

Pin hole drilling.

Current average rejection for last 6 months

27 Nos/month 0.11% Maximum and Minimum rejection in last 6 months

Maximum rejection in a month - 34 Nos -June06

Minimum rejection in a month - 23 Nos - Mar06


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Process Mapping

Input MaterialCasting

Opn. 10 - Disc MillingM/C : SPM Milling

Opn. 30 - Pin HoleDrilling

M/C : Systec

Opn. 40 - Feed & BleedM/C : Stama

Opn. 20 - Lug MillingM/C : Cincinnati

Milling

Opn. 60 - Rough BoreM/C : Column Drill

Opn. 50 - Banjo MillingM/C : Cincinnati Milling

Opn. 70 - Finish BoreM/C :1SC & LMW

Rejection occurring

stage


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Phase

Month Month Month

W1 W2 W3 W4 W1 W2 W3 W4 W1 W2 W3 W4

Define

Measure &Analyze

Improve

Control

Project Planning

PhasesPlannedStart date

PlannedCompletiondate

Actual startdate

Actualcompletion date

Status

Define 03.07.2006 08.07.2006 03.07.2006 07.07.2006 Completed

Measure & Analyze 10.07.2006 05.08.2006 15.07.2006 08.08.2006 Completed

Improve 07.08.2006 26.08.2006 10.08.2006 05.09.2006 Completed

Control 28.08.2006 09.09.2006 08.09.2006 06.10.2006 Completed

Planned Completed


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`Photograph of defect part

CastingPin hole drilling

(Problem operation) Finished component

Min 4.8mm


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Process flow


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Sq.

no Process step

Incoming source of

variation Symbol Desired outcomes Type Process characteristics

10 DISC MILLING 1.HARDNESS 1.DISC MILLING RADIUS BP 1.SPEED

LOADING 2.CASTING DIMENSION 2.RADIUS DEPTH BP 2.FEED

( TOOLING LOCATION W.R.TO 3.CENTER SHIFT OF RADIUS BP 3.COOLANT FLOW

CENTER OF CASTING ) 4.CLAMPING PRESSURE

5.TABLE MOVEMENT

6.LOCATING PIN IN FIXTURE

7.BUTTING THE CASTING BY

OPERATOR

8.SETTING DIMENSION FOR RADIUS

MILLING,RADIUS DEPTH AND

CENTER SHIFT OF RADIUS

20 LUG MILLING CENTER SHIFT OF RADIUS 1.FLANGE THICK NESS BP 1.SPEED

LOADING 2.DIMN. 11.5 MIN. FROM HOLE CENTER BP 2.FEED

3.DIMN 24.20 / 23.80 MM FROM "V" FACE BP 3.SPINDLE AXIAL AND RADIAL

PLAY

30 PIN HOLE 1.CASTING DIMENSION 1.PIN HOLE DIAMETER BP 1.SPEED

DRILLING ( SYMMETRICITY,CAVITY TO 2.PIN HOLE POSITION BP 2.FEED

LOADING CAVITY,CENTER SHIFT OF 3.WALL THICKNESS BP 3.COMPONENT BUTTING LOCATION

RADIUS ) 4.CLAMPING PRESSURE

2.RADIUD DEPTH

3.CENTER SHIFT OF RADIUS

Process flow diagram


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Process

FMEA


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Process FMEAPROCESS

STEPFAILURE MODE POTENTIAL CAUSES OCC

CURRENT PROCESS

CONTROL (TYPE - B)

CURRENT PROCESS

CONTROL (TYPE - C)

CURRENT PROCESS

CONTROL (TYPE - A)DET RPN

DISC MILLING 1.DISC MILLING 1.HARDNESS 1 NIL RECEIVING INSPECTION NIL

RADIUS AS PER SHOWA SINGLE

OVERSIZE SAMPLING PLAN

UNDERSIZE ( ACCEPTANCE LEVEL 0 )

RESP : INSPECTOR

2.RADIUS DEPTH

OVERSIZE 2.CASTING DIMENSION NIL RECEIVING INSPECTION NIL

UNDERSIZE ( TOOLING LOCATION W.R AS PER SHOWA SINGLE

TO CENTER OF CASTING ) SAMPLING PLAN

3.CENTER SHIFT ( ACCEPTANCE LEVEL 0 )

OF RADIUS RESP : INSPECTOR

OVERSIZE

UNDERSIZE 3.BUTTING THE CASTING NIL POKA - YOKE ONCE IN 2 HRS BY QA 6 6

BY OPERATOR PROVIDED PRE-DESPATCH

INSPECTION

AS PER SHOWA SINGLE

SAMPLING PLAN

( ACCEPTANCE LEVEL 0 )

RESP : INSPECTOR

4.TABLE MOVEMENT NIL IT IS IN PM CHECK NIL

LIST


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PROCESS


CURRENT PROCESS

CONTROL (TYPE - B)

CURRENT PROCESS

CONTROL (TYPE - C)

CURRENT PROCESS


LUG FLANGE 1.CENTER SHIFT OF RADIU 1 PROCESS CONTROL NIL ONCE IN 2 HRS BY QA 6 6

MILLING THICKNESS CHART PRE-DESPATCH

VARIATION CHECK 1 NO/HOUR INSPECTION

RESP: OPERATOR AS PER SHOWA SINGLE

SAMPLING PLAN


INSPECTOR

2.SPINDLE AXIAL AND NIL ADDEED IN THE

RADIAL PLAY PM CHECK LIST

Process FMEA


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Process FMEAPROCESS


CURRENT PROCESS

CONTROL (TYPE - B)

CURRENT PROCESS

CONTROL (TYPE - C)

CURRENT PROCESS


PIN HOLE WALL 1.CASTING DIMENSION 4 NIL RECEIVING INSPECTION NIL 6

DRILLING THICKNESS ( SYMMETRICITY,

UNDERSIZE CAVITY TO CAVITY &

BOSS DIAMETER )

2.RADIUS DEPTH PROCESS CONTROL NIL 100% IN FINAL AREA 5 20

CHART USING GAUGE

CHECK 1 NO/HOUR ONCE IN 2 HRS BY QA

RESP : INSPECTOR PRE-DESPATCH

INSPECTION

3.CENTER SHIFT OF PROCESS CONTROL NIL AS PER SHOW A SINGLE

RADIUS CHART SAMPLING PLAN

CHECK 1 NO/HOUR ( ACCEPTANCE LEVEL 0 )

RESP : INSPECTOR RESP : INSPECTOR


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Calibration


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Variation due toInstrument


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Data Collection

1. Instrument Selected : Vernier Caliper

2. Instrument Number : SM 0200

3. Least Count : 0.01 mm

4. No. of Samples : 5 Nos

5. No. of Appraiser : 3


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Bias Estimation

Following are the readings obtained during calibration of Vernier Caliper

Master Value = 20 mmError = 0.00001 mm

S.No Reading

1 20.01

2 20.00

3 20.00

4 20.01

5 20.02

Average = 20.008

Error = Actual Value Master Value

Error = 20.008 20.000

Error = 0.008

Master Error = 0.01 microns = 0.00001 mm


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Bias Estimation

Standard Deviation( s)= 0.008

Standard Deviation of Averages( s (X bar) )= s/ Sqrt n

= 0.008 / Sqrt 5

=0.008 / 2.236

= 0.0036

t value for 5 data =2.7764

Random Uncertainty = t * (s(X bar))

=2.7764 * 0.0036

=0.009995


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Bias EstimationSystem Uncertainty

Total Uncertainty= Sqrt( (RU)2 + (SU)2 )

= Sqrt( (0.009995)2 + (0.00001)2 )

= 0.0099

Calculating Upper and Lower Boundary

UL= Error + TU

UL= 0.008 + 0.0099

UL= 0.0179

LL= Error - TU

LL = 0.008 - 0.0099

LL= - 0.0019

0 lies between the 2 limits. Hence the Error is 0.


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Conclusion for Uncertainty

Calculate TU/Tolerance %= 0.0099 / 1 * 100

= 0.99 %

0.99 % is < 25%

So the Uncertainty is Acceptable

Bias is 0

Uncertainty percentage is < 25%

Hence this Instrument can be used for ourproject.


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Linearity EstimationMethod-2 :Graphical Method

Following is the data collected after calibration

Master value 20 60 90 120 140

Error 0.00001 0.00000 0.00001 0.00004 0.00003

1 20.01 60.02 89.99 120.02 140.00

2 20.00 59.99 90.01 120.00 140.00

3 20.00 60.02 90.02 120.01 139.98

4 20.01 60.01 90.01 120.00 139.99

5 20.02 60.02 90.00 120.00 139.99

Average 20.008 60.012 90.006 120.006 139.992

Error 0.008 0.012 0.006 0.006 - 0.008

Master Slip Gauge InstrumentVernier Caliper

All dimensions in mm

G hi l M h d


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- 0.015

- 0.010

- 0.005

0.015

0.010

0.005

0.000

20 12010040 8060 140 160

Error

Master Value

Graphical Method

0 lies between the highest and lowest point. So it is Linear


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Gauge R&RStudy


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Appraiser Trial Sample 1 Sample 2 Sample 3 Sample 4 Sample 5

S.DoraisamyT1 12.99 13.08 12.96 12.99 12.98

T2 13.07 13.06 12.96 12.96 12.99

S.GaneshKumar

T1 12.98 12.94 12.92 12.94 12.94

T2 12.90 13.03 12.96 12.99 12.92

V.VadiveluT1 12.97 13.00 12.96 12.99 12.97

T2 12.99 13.02 13.02 12.98 12.99

S.Doraisamy 0.08 0.02 0.00 0.03 0.01

S.Ganesh Kumar 0.08 0.09 0.04 0.05 0.02

V.Vadivelu 0.02 0.02 0.06 0.01 0.02

0.55

15=R

R= 0.037

Maximum Range = 0.09


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To check the Consistency of the range

UCL = D4*R

UCL = 3.267*0.037UCL = 0.121

LCL = 0

With in person Variation = 0.09

UCL is > With in person Variation

So It is Consistent

E i i R bili ( V i i i h i )


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Estimating Standard Deviation

=R

d2s

=0.037

2.48s

s= 0.015

Estimating Variation

5.15s= 5.15*0.015

= 0.077

Estimating Repeatability ( Variation with in person )

m = 5

g = 1

d2= 2.48

At 99% Confidence level

Actual EstimationWith in person 0.09 0.077

Person to Person Variation + With in person variation

Person to Person Variation only

Total R&R


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Mean

S.Doraisamy 13.030 13.070 12.960 12.975 12.985 13.004

S.Ganesh Kumar 12.940 12.985 12.940 12.965 12.930 12.952

V.Vadivelu 12.980 13.010 12.990 12.985 12.980 12.989

Estimating Person to Person and With in person Variation

Range = 0.052

Finding out the Range

R= 0.052

Estimating Standard deviation

=0.052

2.48s

s= 0.021

m = 5

g = 1

d2= 2.48


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Estimate Variation

5.15s= 5.15*0.021

= 0.108

Actual Estimation

With in person 0.090 0.077

Person to Person Variation + With in person variation 0.052 0.108

Person to Person Variation only

Total R&R


To find Reproducibility (Person to Person Variation) we have toremove Variation with in person from this

E ti ti R d ibilit


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Person to Person Variation

Actual Estimation



Person to Person Variation only 0.044 0.105

Total R&R

= Sqrt((AV)2 ((EV)2/(n*r)))

= Sqrt((0.052)2 ((0.090)2/(2*5)))

= 0.044

Estimating Person to Person Variation

= Sqrt((AV)2 ((EV)2/(n*r)))= Sqrt((0.108)2 ((0.077)2/(2*5)))

= 0.105

Estimating Reproducibility


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Actual R&R

Actual Estimation



Person to Person Variation only 0.044 0.105

Total R&R 0.100 0.130

= Sqrt((Repeatability)2 + (Reproducibility)2)

= Sqrt((0.090)2 + (0.044)2)

= 0.100

Estimating R&R

= 0.130

= Sqrt((Repeatability)2 + (Reproducibility)2)

= Sqrt((0.077)2 + (0.105)2)


l l l


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Calculating R&R / Tolerance%

Calculated R&R/Tolerance * 100 = 0.130 / 1*100

= 13 %

Takingsfrom my project

s = 0.082

5.15s= 5.15*0.082

= 0.4223

R&R/Part to Part Variation = 0.130 / 0.4223

= 30.8 %

Calculating R&R / Part to Part Variation%

Since R&R/Part to Part Variation is > 30%. We cannot use thisInstrument for Data Collection in our Project.

We allowed a deviation to our self to use this for data collection

since the deviation is too small.

Ph 1 P bl D fi iti


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Pareto (Based on last 6 months data)

21% of the Total rejection is due to pin hole less wallthickness.

Qty produced - 140782 nos.Total scrap Qty - 787 nos.Scrap Percentage - 0.55 %Pin hole out of pos. scrap 163nos.Pin hole less wall thickness % - 0.11 %


HOUSING PARETO CHART FOR

THE MONTH OF JAN'06 TO JUNE'06 ( SIX MONTHS)

36 33 29 28

6777

414247 45 44 40 37

58

163

21%

31%

40%47%

53%59%

65% 70%

75% 80%

85% 90%

94% 98% 100%

0

20

40

60

80

100

120

140

160

180

PIN

HOLE

LESS

WALL

THICKNESS

PIN

HOLE

CHAMFE

RD

IAO

/S

BORE

DIA

O/S

FEED

PORTSPOTFA

CE

DAMAGE

FEED

PORTS

.FACE

CHAT.MARK

BLEED

PORTSEATING

DAMAGE

FEED

PORTSHIFT

BLEED

PORTOUTOFPOSITION

LUG

MILLING

STEP

SEALGROOVE

DIA

O/S

FEED

PORTCORE

DIA

O/S

BORE

STEP

M10

THREAD

DAMAGE

BORE

DAMAGE

M10

THREAD

WASH

OUT

DEFECTS

REJECTQTY

0%

20%

40%

60%

80%

100%

120%

CUMULATIVEPERCENTAGE

As per Pareto Pin Hole Less Wall thickness is thehighest rejection. Hence this defect was taken for the

project.


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COPQ (Cost of Poor Quality) Calculation


Number of pieces rejected last month(for the part number identified for study)

34 ( June06)

Number of pieces scrapped last month 34

Number of pieces reworked last month _

Scrap cost/piece 298

Rework cost/piece _Total scrap cost (Rs. Lakhs) for lastmonth

Rs 10,132

Total rework cost(Rs. Lakhs) for lastmonth

_

Total Rejection cost (Rs. Lakhs) for lastmonth Rs 10,132

Extrapolated Total rejection cost (Rs.Lakhs) for one year

Rs : 1,21,584

Horizontal Deployment N.A

h bl f


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Listing Down Suspected Sources of Variations

Man Input Material

MachineProcess (Pin hole drilling)

Pin hole less wall

thickness

Radial play in Milling &

Systec machines

Cavity to cavity variation

Dia. of the bosses

Symmetricity of the bosses

Radius depth in SPM

Milling

Center Shift of RadiusLoading variation in

pin hole operation


Clamping variation in Pin hoe operation

Listing Down all SSVs


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Listing Down all SSV s

1.Incoming Material 1.Cavity to Cavity Variation

2.Boss diameter

3.Symmetricity of Boss

4.Radius depth in SPM Milling

5.Center shift of radius

7.Clamping in Pin hole operation

SSVs

6.Loading Variation in pin hole operation

3.Process

4.Machine 8.Spindle Runout in Milling and Systec Machine

2.Operator


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The following SSVs are Constant and Hence are not considered forfurther study for the Y at this Stage

1.Loading - Mistake Proof Arrangement

(Both in previous operation & in problem generated operation)

2.Clamping - Constant

3.Spindle Runout in Systec machine - Constant

Ph 1 P bl D fi iti


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1. Input MaterialCasting Related

1.Cavity to Cavity Variation

2.Boss diameter


Previous (Earlier) operation Related

1.Radius Milling depth

2.Center shift of radius

2. SSVs are Nilin the Process (Drilling Operation) at which Y is created

Suspected Sources of Variation (SSVs) for the Problem statement

1st level SSVs

ALL THE ABOVE SSVs ARE VARIABLES

Ph 1 P bl D fi iti


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SSVsCurrent

Specification

Input Material

Boss diameter 20.0 + 0.60

Cavity number 7,8,9 & 10

Symmetricity 26.50 + 0.60

Previous Operation

related

Radius depth 133.70 + 0.30

Center shift of radius 48.50 / 47.50

Response (Hole ) Y = Wall thickness 4.80 mm to 5.80 mm

P bl St t t


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Problem Statement

Cavity Number

4.8 mm to 5.8 mm.

(Wall thickness)

20+0.6 (Boss dia)

Boss - A Boss - B

47.5 / 48.5

133.7 +0.3

B with respect to A

Y = Wall thickness

X = Symmetricity,Boss diameter,Cavity to Cavity Variation,Radius depth and centershift of radius

Si Si T l d


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Six Sigma Tools used

Phase Tools

Define 1. Process Mapping

2. Process FMEA3. Pareto

4. Calibration

5. Gauge R&R Studies


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Measure andAnalyze Phase

Machines


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Machines

SPM Milling Systec

Root Cause = X Response = Y

Suspected Source Machine Generating Machine

DOE Tool Selection


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DOE Tool Selection

The identified SSVs are Measurable on both Good and Badcomponents and are Input related.

Hence DOE Tool PAIRED COMPARISONwas selected.

Y= f(x)

Y = Response

= Wall Thickness

X = SSVs

Input Material Parameters

1.Cavity to Cavity

2.Boss


4.Radius Depth

5.Center Shift in Radius


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Measurement

Data Collection


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Data Collection

8 Good parts (Best of Best) and 8 Bad parts (Worst of Worst)

based on Wall thickness (Response) were selected for study.

WOW parts were collected from already rejected lot as thecurrent rejection rate for this defect is 0.11% and need to

wait 8 to 9 thousand numbers (Which is 10 daysproduction) to get 8 Bad components. BOB parts werecollected from a shifts production Quantity.

The parts were marked as B1,B2,B3,B4,B5,B6B7 & B8

W1,W2,W3,W4,W5,W6,W7& W8

Data Collection


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S.No

Input Material SSVs (Casting Related)Earlier Process Related

(Machining Related)Specification

Response CavityNo

Boss

Dia - A200.6mm

Boss

Dia - B200.6 mm

Symmetricity Radius Depth133.70.3mm Center shift ofRadius Response

B1 GOOD 7 21.12 21.38 0.70 133.67 47.82 5.57

B2 GOOD 8 21.00 20.88 0.55 133.75 48.32 5.58

B3 GOOD 9 20.98 21.17 0.60 133.62 48.10 6.00

B4 GOOD 9 20.80 20.80 0.80 133.80 48.00 5.57B5 GOOD 10 21.90 21.00 0.60 133.72 47.80 5.90

B6 GOOD 10 20.97 20.90 0.50 133.55 48.20 5.80

B7 GOOD 8 21.80 21.00 0.80 133.66 48.37 5.70

B8 GOOD 9 20.80 20.80 0.50 133.70 48.20 6.00

W1 BAD 7 21.37 22.00 1.50 133.90 47.88 4.78

W2 BAD 7 21.37 21.33 1.35 134.13 47.70 4.70W3 BAD 7 20.84 20.90 0.78 133.70 48.17 4.70

W4 BAD 7 21.30 21.33 1.10 134.21 47.95 4.75

W5 BAD 8 20.85 20.80 0.70 134.15 47.45 4.79

W6 BAD 10 20.80 20.80 1.12 134.02 47.80 4.78

W7 BAD 7 20.80 21.00 0.80 133.95 47.50 4.57

W8 BAD 7 20.88 21.40 0.70 134.07 47.75 4.76

Data Collection


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Analysis

Analysis Step1


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S.No Response Cavity no

1 GOOD 7

2 GOOD 8

3 GOOD 9

4 GOOD 9

5 GOOD 10

6 GOOD 10

7 GOOD 8

8 GOOD 9

1 BAD 7

2 BAD 7

3 BAD 7

4 BAD 7

5 BAD 8

6 BAD 10

7 BAD 7

8 BAD 7

S.No Response Boss A Boss B

1 GOOD 20.88 20.80

2 GOOD 20.80 20.80

3 GOOD 20.80 20.88

4 GOOD 20.90 20.90

5 GOOD 20.97 21.00

6 GOOD 20.98 21.10

7 GOOD 21.10 21.178 GOOD 21.12 21.38

1 BAD 20.80 20.80

2 BAD 20.80 20..90

3 BAD 20.84 21..90

4 BAD 20.85 21.00

5 BAD 20.88 21.33

6 BAD 21.30 21.33

7 BAD 21.37 21.40

8 BAD 21.37 22.40

Analysis Step1To find out the root causes among the chosen SSVs

Parameter - 1 Parameter - 2

All Cavity numbers are both in goodand bad components. Hence Cavity

Variation is not the cause forVariation in Y

In both Boss s both Max. and Min. sizes are

in Bad Components. Hence these dias are

not the reason for Variation in Y

Analysis Step1


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S.No Response Symmetricity

1 GOOD 0.50

2 GOOD 0.50

3 GOOD 0.55

4 GOOD 0.60

5 GOOD 0.60

6 GOOD 0.70

7 GOOD 0.80

8 GOOD 0.80

1 BAD 0.70

2 BAD 0.70

3 BAD 0.78

4 BAD 0.80

5 BAD 1.10

6 BAD 1.127 BAD 1.35

8 BAD 1.50

S.No ResponseRadiusDepth

1 GOOD 133.55

2 GOOD 133.623 GOOD 133.66

4 GOOD 133.67

5 GOOD 133.70

6 GOOD 133.72

7 GOOD 133.75

8 GOOD 133.80

1 BAD 133.70

2 BAD 133.90

3 BAD 133.95

4 BAD 134.02

5 BAD 134.07

6 BAD 134.13

7 BAD 134.15

8 BAD 134.21

S.No Response CenterShift

1 GOOD 47.80

2 GOOD 47.823 GOOD 48.00

4 GOOD 48.10

5 GOOD 48.20

6 GOOD 48.20

7 GOOD 48.32

8 GOOD 48.37

1 BAD 47.45

2 BAD 47.50

3 BAD 47.70

4 BAD 47.75

5 BAD 47.80

6 BAD 47.88

7 BAD 48.17

8 BAD 47.95

y pParameter - 4Parameter - 3 Parameter - 5

SymmetricityMin & Max do notbelong to the same category. NorMin or Max are in both thecategories. Hence this is one of

the causes.

Radius DepthMin & Max do notbelong to the same category. NorMin or Max are in both thecategories. Hence this is one of

the causes.

Center ShiftMin & Max are not inthe same category. Nor Min orMax are in both the categories.Hence this is one of the cause.

1STlevel funneling


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1.Cavity to

Cavity2.Boss diameter3.Symmetricity4.Radius Depth5.Center Shift

CONCLUSION:

From the above, Cavity to Cavity andBoss Parameter are not the causes for the

response.That leaves with Symmetricity,Radius

Depth and Centre shift of Radius are potentialcauses for the rejection.

g

2ndlevel SSVs

1.Symmetricity2.Radius Depth

3.Center Shift

SSVs remains after 1stlevel funneling

1stlevel funneling ToolDOE-Paired Comparison

1.Symmetricity2.Radius Depth3.Center Shift

Proceeding further to find whether they are the root causes

Analysis Step2


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Arranging values in Ascending order

Sl. No Response

1 G

2 G

3 G

4 G

5 G6 G Top Line

7 B

8 B

9 B

10 B

11 G

12 G Bottom Line

13 B

14 B

15 B

16 B

Symmetricity

0.50

0.50

0.55

0.60

0.600.70

0.70

0.70

0.78

0.80

0.80

1.50

0.80

1.10

1.12

1.35

SSV1 : Symmetricity

Analysis Step2

Top count =51/2

Bottom Count = 4Total Count =91/2

Total Count is > 6.Hence this SSV is oneof the root causes for the response at 95%

confidence level

Analysis Step2


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SSV2 : Radius DepthAnalysis Step2

Top count =41/2

Bottom Count = 7Total Count =111/2


Confidence level

Sl. No Response

1 G

2 G

3 G

4 G

5 G Top Line

6 B7 G

8 G

9 G Bottom Line

10 B

11 B12 B

13 B

14 B

15 B

16 B

134.15

134.21

133.95134.02

134.07

134.13

133.72

133.75

133.80

133.90

133.66

133.67

133.70

133.70

Radius depth

133.55

133.62

Analysis Step2


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SSV3 : Center shift of radius

y p

Top count = 5

Bottom Count = 4Total Count = 9

Sl. No Response

1 B2 B

3 B

4 B

5 B Top Line

6 G7 G

8 B

9 G

10 B

11 G12 B Bottom Line

13 G

14 G

15 G

16 G

48.20

48.32

48.37

47.90

48.0048.10

48.17

47.8047.80

47.82

47.88

47.45

47.50

47.70

47.75

Radius centre

47.45


Confidence level

Conclusion


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Conclusion

SSV1=Symmetricity

SSV2 =Radius Depth

SSV3= Center shift of Radius

Are the root causes for the Wall thickness Variation (Response Y)

Fixing Specification


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Fixing Specification

Since all the three parameter have count more than 6,New specifications arearrived at

New specifications are based on the sizes from good components.

Parameter Total Count New Specification

Symmetricity 91/2 < 0.60

Radius Depth 111/2 133.55 / 133.67

Center Shift of Radius 9 48.17 / 48.37

Proceeding Further


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Proceeding Further

Can we control the new specification to with in the limits arrived at?

Radius depth and Radius shift are set dimension in the Machine. Hence can becontrolled.

Symmetricity is created at Foundry and they have agreed study to restrictSymmetricity in 0.60 Max.

A l i


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Analysis

Checking the Contribution of Each Root Causefor the Response

Since there are 3 Parameters which affect theResponse, I have selected DOE tool

FullFactorial

for checking the contribution.

Stage 0: Factorial Analysis


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Stage 0:

Identification of (+) Setting and (-) Setting

ParameterIdentified As

Actual ParameterUnit of

Measurement

(+)

Setting

(-)Setting

A Symmetricity In mm < 0.60 > 1.00

B Radius Depth In mm 133.50 134.05

C Center Shift In mm 48.30 47.60

These are the parameters identified as root causes. (+) Settings are those which

produced Good components and (-) Settings are those which produced Bad

components.

Factorial Analysis

Stage 1: Making of Factorial Table


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Stage 1: Making of Factorial Table

A B C

Response A*B B*C A*C A*B*C

Symmetricity Radius Depth

Center Shift

of Radius

- - - + + + -

+ - - - + - +

- + - - - + +

+ + - + - - -

- - + + - - +

+ - + - - + -

- + + - + - -

+ + + + + + +

We have 3 Parameters

Hence No. of Rows = 2n = 2x2x2 = 8No. of Columns = n-1 = 8-1 = 7

Stage 1: Data Collection


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g

+ -

Symmetricity < 0.60 > 1.00

Radius Shift 133.50 134.05

Center Shift 48.30 47.60

Second RunSpecification for Factorial Analysis

Good Response Bad Response

G1 5.88 B1 4.24

G2 5.35 B2 4.46

G3 5.48 B3 5.20

G4 5.58 B4 4.38

G5 5.48 B5 4.78

G6 5.63 B6 4.56

Mean 5.56 Mean 4.60

Range 0.53 Range 0.96

First Run


G1 5.24 B1 4.82

G2 5.17 B2 4.72

G3 5.18 B3 4.63

G4 5.48 B4 4.79

G5 5.38 B5 4.93

G6 5.50 B6 4.63

Mean 5.33 Mean 4.75


Third Run


G1 5.54 B1 4.84

G2 5.43 B2 4.84

G3 5.32 B3 4.61

G4 5.32 B4 4.75

G5 5.28 B5 4.37

G6 5.28 B6 4.40

Mean 5.36 Mean 4.64


+ - - - + - + + -- - -


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S.No Response

1 4.92

2 4.89

3 5.26

4 4.75

5 5.11

6 4.71

Mean 4.94

Range 0.55

+ - +

S.No Response

1 5.17

2 5.50

3 5.11

4 5.30

5 5.27

6 5.45

Mean 5.30

Range 0.39

S.No Response

1 4.79

2 4.94

3 4.76

4 4.78

5 5.06

6 4.68

Mean 4.84

Range 0.38

S.No Response

1 4.70

2 4.71

3 4.70

4 4.69

5 4.14

6 4.71

Mean 4.61

Range 0.57

- + +

S.No Response

1 4.97

2 5.23

3 4.99

4 5.00

5 5.04

6 4.99

Mean 5.03

Range 0.26

- - +

S.No Response

1 5.21

2 5.38

3 5.50

4 5.17

5 5.28

6 5.24

Mean 5.30

Range 0.33

+ + +

S.No Response

1 5.88

2 5.35

3 5.48

4 5.58

5 5.48

6 5.63

Mean 5.56

Range 0.53

S.No Response

1 4.24

2 4.46

3 5.20

4 4.38

5 4.78

6 4.56

Mean 4.60

Range 0.96

Factorial Analysis


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y

A B C Response

Average wall

thickness

Symmetricity Radius Depth Center Shift of Radius

- - - 4.60

+ - - 4.94

- + - 4.84

+ + - 4.61

- - + 5.30

+ - + 5.30

- + + 5.03

+ + + 5.56

To Check Contribution of each Parameter


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o C ec Co t but o o eac a a ete

Response from Collected Data

A B CResponse AxB BxC AxC AxBxC

SymmetricityRadiusDepth

Center Shiftof Radius

- - - 4.60 + + + -

+ - - 4.94 - + - +

- + - 4.84 - - + +

+ + - 4.61 + - - -

- - + 5.30 + - - +

+ - + 5.30 - - + -

- + + 5.03 - + - -

+ + + 5.56 + + + +

+

0.64

-

0.10

+

2.20

-

0.04

+

0.08

+

0.420

+

1.10

+

0.16

-

0.025

+

0.55

-

0.01

+

0.02

+

0.105

+

0.275

Contributionof parameters

Total

Conclusion


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Conclusion

Parameter ContributionWhen the Parameter is moved from- to+,Response Increases or Decreases

A 0.160 Increases

B 0.025 Decreases

C 0.550 Increases

Based on the Factorial Analysis done for the data the Conclusions are given inthe table below

Using Minitab


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Using Minitab

Using Minitab


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g

Using Minitab


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Using Minitab



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70

g

Phase Tools

Measure and

Analyze

1.Paired Comparison

2.Full Factorial


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Improvement

Phase


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Validating the

Root Causes

Selection of DOE Tool


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Since Good and Bad parts Can be created alternately,We selected B Vs C Toolto Validate the root cause(s)

Deciding B and C Condition for the Project

The Tool used for finding out the root cause is Paired Comparison.

Hence the B condition are those corresponding to Good category and

The C condition are those corresponding to Bad condition.

Symmentricity Radius Depth Centre shift of Radius

B Condition < 0.60 133.55 / 133.67 48.17 / 48.37

C Condition > 1.00 133.90 / 134.10 47.50 / 47.70

Symmetricity Radius Depth Center shift of RadiusDeciding Sample Size


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S. No Symmetricity Response

1 0.50 G

2 0.50 G

3 0.55 G

4 0.60 G

5 0.60 G

6 0.70 G

7 0.70 B

8 0.70 B

9 0.78 B

10 0.80 B

11 0.80 G

12 0.80 G

13 1.10 B

14 1.12 B

15 1.35 B

16 1.50 B

S. No Radius Depth Response

1 133.55 G

2 133.62 G

3 133.66 G

4 133.67 G

5 133.70 G

6 133.70 B

7 133.72 G

8 133.75 G

9 133.80 G

10 133.90 B

11 133.95 B

12 134.02 B

13 134.07 B

14 134.13 B

15 134.15 B

16 134.21 B

S. No Center Shift Response

1 47.45 B

2 47.45 B

3 47.50 B

4 47.70 B

5 47.75 B

6 47.80 G

7 47.80 G

8 47.82 B

9 47.88 G

10 47.90 B

11 48.00 G

12 48.10 B

13 48.17 G

14 48.20 G

15 48.32 G

16 48.37 G

Top count=51/2

Bottom count=4

Total count=91/2

Top count=41/2

Bottom count=7

Total count=111/2

Top count=5

Bottom count=4

Total count=9

Top

line

Bottom

line

Top

line

Bottom

line

Top

line

Bottom

line

Symmetricity Radius Depth Ce te s t o ad us

# Since Total Count is less than 16,We need to Machine 6B & 6C

Data Collection


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Deciding Sample Size

Assumption: There could be some overlap in the responses between

B & C condition as while establishing the rootcauses the Total counts were less then 12 for all the 3SSVs. Hence 6B & 6C were selected

Deciding whether 6B & 6C are to be in Nos. or in BatchesSince the response (Wall thickness) is Variable 6B & 6C will be in Nos.

Deciding what big Y will be Monitored

The big Y is Wall thickness (Response) and is Variable.This will be Monitored in Actual Values

Deciding Data collection Methodology

Decided to machine 6B and 6C by creating B and C condition alternatively

Specifications for Current & Better


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Specifications for Current & Bettercondition

CharacteristicBetter condition(New specification)

Current condition

Symmentricity < 0.60 > 1.00

Radius Depth 133.55/ 133.67 133.90 / 134.10

Centre shift of Radius 48.17 / 48.37 47.50 / 47.70

Data Collection


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Example NoResponse Y by

B ConditionResponse Y by

C Condition

1 5.88 4.242 5.35 4.46

3 5.48 5.20

4 5.58 4.38

5 5.48 4.78

6 5.63 4.56

Note :

1. During drilling operation the B Condition & C Condition were alternated for each piece

2. Since there is no overlap, the root causes are correct

Y = 4.80mm to 5.80mm

Analysis for 6B and 6C


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S.No Condition Response Y

1 C 4.24

2 C 4.38

3 C 4.46

4 C 4.56

5 C 4.78

6 C 5.20

7 B 5.35

8 B 5.48

9 B 5.48

10 B 5.58

11 B 5.63

12 B 5.88

Finding Whether the cause is correct (Another Way)

Top Count =6

Bottom Count =6Total Count =12

Since Total Count is >6,the root causes are correct.

if i h f

Analysis


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Quantifying the amount of Improvement

The Average of B = Xb = 5.57 mm

The Average of C = Xc = 4.60 mm

The Difference between Xb & Xc = Xb-Xc = 0.97 mm

Sigma value of B Values = Sigma B = 0.1813

K Value at 95% CL for 6,6 = 2.96

K * Sigma = 2.96 * 0.1813 = 0.537

( Xb Xc ) >= K * Sigma

0.97 > 0.537

Since Xb Xc is greater K * Sigma.

Improvement has taken place at the assumed C.L of 95%

The Amount of Improvement = Xb - Xc

= 0.97 mm

Of th 3 t


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Of the 3 root causes

Symmetricity is Foundry related dimension

Radius Depth and Center shift of radius are machining relateddimension. They are set and locked.

During the middle of the Project stage we discussed with Foundry for

maintaining to new specification of Symmetricity to 0.60 max. They said they

need a tolerance of 1.2 mm max. for their process and they will keep trying tobring it to 0.60 max.

Hence we proceeded with the project with Symmetricity up to 1.20 mm.

6 Nos were produced with Symmetricity 1.00 to 1.20 mm and the other two

dimensions to New specification.The response is as follows.

BOB and WOW Parts specification


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BOB and WOW Parts specification

Characteristic Better condition Current condition

Symmentricity A < 0.60 1.00 to 1.20

Radius Depth B 133.55 133.55

Centre shift of Radius - C 48.30 48.30

Data Collection


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Example NoResponse Y by

B ConditionResponse Y by C Condition with B

Condition data except Symmetricity

1 5.88 4.97

2 5.35 5.23

3 5.48 4.99

4 5.58 5.00

5 5.48 5.04

6 5.63 4.99

Note :

1. Since there is no overlap, the root causes are correct

Y = 4.80mm to 5.80mm



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K * Sigma = 2.96 * 0.1813 = 0.54


0.53 < 0.54

Since Xb Xc is Less than K * Sigma.

Improvement has not taken place at the assumed C.L of 95%



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84






K * Sigma = 2.61 * 0.1813 = 0.473


0.53 > 0.473

Since Xb Xc is More than K * Sigma.

Improvement has taken place at the assumed C.L of 90%

The Amount of Improvement = Xb - Xc

= 0.53 mm


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Animation


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Phase Tools

Improve 1. B Vs C


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Control Phase

We have Introduced the following Controls forth SSV


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the SSVs

SSV 1 Symmetricity : Foundry has agreed to study the process and reduce

the variation in Symmetricity to < 0.60. Till then they

will supply castings up to 1.20mm Symmetricity.

However,to ensure the coming castings whether they

are received with in 1.20mm Symmetricity thefollowing check has been introduced.

For every batch 30nos are taken at random and

Symmetricity is measured and the lot is accepted if

6s level is < = 75% of Tolerance.

Symmetricity Variationi i I i i l


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S.NoSymmetricity

in mm

1 0.25

2 0.30

3 0.20

4 0.25

5 0.10

6 0.05

7 0.15

8 0.20

9 0.20

10 0.24

11 0.25

12 0.25

13 0.05

14 0.45

15 0.20

S.NoSymmetricity

in mm

16 0.10

17 0.30

18 0.15

19 0.18

20 0.43

21 0.45

22 0.40

23 0.4524 0.40

25 0.10

26 0.20

27 0.50

28 0.52

29 0.3030 0.10

s = 0.1364

6s= 0.8181

6slevel is lesser than 75% of the Tolerance

Therefore the lot is Accepted

Incoming materialchecked on: 27.09.06

Casting Tolerance = 1.20 mm

Symmetricity VariationS i i I i t i l


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S.NoSymmetricity

in mm

1 0.70

2 0.95

3 0.45

4 0.80

5 0.30

6 0.60

7 1.42

8 0.40

9 0.15

10 0.83

11 0.65

12 0.60

13 0.65

14 0.40

15 0.25

S.NoSymmetricity

in mm

16 0.07

17 0.08

18 0.25

19 0.70

20 0.80

21 0.91

22 0.76

23 0.5324 0.57

25 0.53

26 0.95

27 0.05

28 0.37

29 0.0730 0.80

s = 0.3221

6s= 1.9327

6s

level is greater than 75% of the Tolerance

Therefore the lot is Rejected

Incoming materialchecked on :29.09.06

Casting Tolerance = 1.20 mm

SSV 2 & 3 Radius Depth and Center Shift of Radius :


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These are Setting dimensions in Milling Machine.Hence every

time when setting takes place or tool is changed, the setting will

be controlled based on response . The parameters are locked in

the system and operator cannot change. This can vary only due to

Wear in the Machine parts and Fixture parts. Periodical

Inspection and change of Wear parts have been introduced.

Further a Checking gauge which can give measured value for

SSVs has been provided to check the parameter at periodical

intervals.Currently the parameters are checked once in a day and

whenever fresh setting is done and cutter changed.

Radius checking Gauge with Master


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Gauge No :S GV 7018

This Gauge is added in theControl plan no 29320155/6

Page no: 3 of 52

Q Parts in the Fixture


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Check List for Q parts in fixtures


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Cell Name :Housing

Machine :SPM

Operation :Milling

S.No Part Name CharacteristicsSpecification

In mm

ActualDimensions

Frequencyin Months

ResultsActionTaken

Q1 R.H Side Sliding block

Working

Condition ofretainer spring

Spring load

1kg on44/46mmlength

1kg on

44mmlength

3 OK ---

Q2 L.H Side butting pin 1 Height 26.50 0.01 26.505 3 OK ---

Q3 L.H Side butting pin 1 Height 25.50 0.01 25.504 3 OK ---

Q4 Bottom butting pin 1 Height 17.00 0.01 17.005 3 OK ---




Checked on: 17.08.06

Check List for Q parts in Machine


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S.No Part NameSpecification

In mm

ActualDimensions

Frequencyin Months

ResultsActionTaken

1 Bearing Worn-out --- 12 OK ---

2 Spindle axial play 0.020.03 mm 0.022 mm 12 OK ---

3 Spindle Radial play 0.020.03 mm 0.027mm 12 OK ---

4X Axis

Repeatability0 - 0.02 mm 0.017 mm 12 OK ---

5 Z AxisRepeatability

0 - 0.02 mm 0.010 mm 12 OK ---

Cell Name :Housing

Machine :SPM

Operation :Milling

Checked on: 04.06.06


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Variation Analysis for Root

Cause and Response

Step 1: Identifying Parameters

R di D h d C Shif f R di h


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Radius Depth and Center Shift of Radius are the two root cause

parameters identified for Variation Analysis as they are

1. Measurable and Variable

2. These root causes are generated from the milling process andnot functional parameters.

3. These are generated from discrete production process and not

from a batch process.4. Can be measured with Non-destructive method.

5. We can detect the parameter immediately if something goeswrong immediately after generation.

6. Apart from the root causes,Variation Analysis for Response (Y)I.e., Wall thickness was also decided to be done to find outwhether the estimated Variation is < = 50% i.e.,6s level

Step 2: Identifying Product / Process StreamIn this case only one Stream is there.

Step 3: Deciding Sample Size

Th f ll i d id d d f ll d


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The following were decided and followed

1. Sample size - 3 Nos

2. Time block chosen - 25

3. Period of Coverage - 4 Hrs

4. Planned events between the Time blocks were captured.

5. Randomized Time intervals were followed.

6. Time blocks were closer because Cycle time is < 3 mins

(Actual is 56 Secs)

Step 4: Collection of Data

Instrument and Dial Gauge with Accuracy which is less than 10%of Tolerance is used.

Step 5: Multi Vari Analysis

Not done as products are not produced from different Streams


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Variation Analysis for

Root Causes (X)

Variation Analysis for Root Cause (X)

P t D t il


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Part Details

CharacteristicRadiusDepth

Part Number 29320155/6 Gauge Number S GV 7018

Unit ofMeasurement

MM PartDescription

HousingMachining

GaugeDescription

RadiusGauge

Target Value Date 08.02.06Gauge Least

Count0.01 mm

Tolerance 0.20 mm

Gauge R&RValue 7.98USL 133.600

Study Dates& Shift

06.07.06

1stShift

LSL 133.400Any other

details----

Data Grouping and Sample details

Number of Groups (Number of Time blocksx number of Streams)

26

Number of Samples in each group (It ispreferable to collect 5 samples continuously

from the process so that the inherentvariations are captured)

3

Study taken to check the variation in the Process at randomized time blocks in SPMMilling for Radius Depth and Center Shift


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S.No Response S.No Response S.No Response S.No Response S.No Response S.No Response S.No Response S.No Response

1 0.00 4 -0.01 7 0.00 10 -0.01 13 -0.02 16 -0.01 19 0.01 22 -0.03

2 -0.01 5 0.03 8 0.01 11 0.01 14 0.01 17 -0.03 20 0.00 23 0.00

3 0.00 6 -0.01 9 0.01 12 -0.01 15 -0.01 18 0.00 21 0.01 24 -0.02


25 -0.02 28 -0.02 31 0.00 34 0.03 37 -0.03 40 -0.03 43 -0.01 46 -0.04

26 -0.02 29 0.00 32 0.00 35 -0.04 38 0.00 41 0.00 44 -0.03 47 -0.05

27 0.02 30 0.00 33 0.02 36 0.02 39 -0.01 42 -0.01 45 -0.02 48 -0.02


49 0.00 52 -0.01 55 -0.01 58 -0.08 61 -0.03 64 -0.04 67 0 70 -0.04

50 0.01 53 0.00 56 0.00 59 -0.03 62 -0.03 65 -0.07 68 -0.04 71 -0.0651 -0.01 54 -0.02 57 -0.06 60 -0.03 63 -0.03 66 -0.04 69 -0.03 72 -0.04

S.No Response S.No Response

73 -0.01 76 0.00

74 0.00 77 -0.02

75 0.00 78 -0.02

T17 T18 T19 T20 T21 T22

T6 T7 T8

T25 T26

T16T11 T12

T23 T24

T13 T14 T15

Actual time=1:44 Actual time=2:00 Actual time=2:10

T1 T2 T3 T4

T9 T10

Actual time=1:30 Actual time=1:35

Actual time=2:45 Actual time=3:05 Actual time=4:02 Actual time=4:11

Actual time=6:17



T5


Actual time=4:55

Actual time=5:13 Actual time=5:20 Actual time=5:28 Actual time=5:48 Actual time=5:54 Actual time=6:00 Actual time=6:07

Time between Time blocks in Minutes

1) 5

2) 9

3) 16

4) 10

5) 10

6) 8

7) 8

8) 9

9) 20

10) 57

11) 9

12) 14

13) 13

14) 12

15) 5

16) 19

17) 7

18) 22

19) 6

20) 6

21) 10

22) 3

23) 10

24) 7

25) 6

Study taken to check the variation in the Process at randomized time blocks in SPMMilling for Radius Depth and Center Shift


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# Part to Part Variation = Max. Value of R = 0.07 mm

# Time to Time Variation = Max. Value of Ave.Min. Value of Ave. = 0.057 mm


1 0.00 4 -0.01 7 0.00 10 -0.01 13 -0.02 16 -0.01 19 0.01 22 -0.03

2 -0.01 5 0.03 8 0.01 11 0.01 14 0.01 17 -0.03 20 0.00 23 0.00

3 0.00 6 -0.01 9 0.01 12 -0.01 15 -0.01 18 0.00 21 0.01 24 -0.02

Ave -0.003 Ave 0.003 Ave 0.007 Ave -0.003 Ave -0.007 Ave -0.013 Ave 0.007 Ave -0.017

R 0.01 R 0.04 R 0.01 R 0.02 R 0.03 R 0.03 R 0.01 R 0.03


25 -0.02 28 -0.02 31 0.00 34 0.03 37 -0.03 40 -0.03 43 -0.01 46 -0.04

26 -0.02 29 0.00 32 0.00 35 -0.04 38 0.00 41 0.00 44 -0.03 47 -0.05

27 0.02 30 0.00 33 0.02 36 0.02 39 -0.01 42 -0.01 45 -0.02 48 -0.02

Ave -0.007 Ave -0.007 Ave 0.007 Ave 0.003 Ave -0.013 Ave -0.013 Ave -0.020 Ave -0.037

R 0.04 R 0.02 R 0.02 R 0.07 R 0.03 R 0.03 R 0.02 R 0.03


49 0.00 52 -0.01 55 -0.01 58 -0.08 61 -0.03 64 -0.04 67 0.00 70 -0.04

50 0.01 53 0.00 56 0.00 59 -0.03 62 -0.03 65 -0.07 68 -0.04 71 -0.06

51 -0.01 54 -0.02 57 -0.06 60 -0.03 63 -0.03 66 -0.04 69 -0.03 72 -0.04

Ave 0.000 Ave -0.010 Ave -0.023 Ave -0.047 Ave -0.030 Ave -0.050 Ave -0.023 Ave -0.047

R 0.02 R 0.02 R 0.06 R 0.05 R 0.00 R 0.03 R 0.04 R 0.02

S.NoResponse S.No Response

73 -0.01 76 0.00

74 0.00 77 -0.02

75 0.00 78 -0.02

Ave -0.003 Ave -0.013

R 0.01 R 0.02

T25 T26

T21 T22 T23 T24T17 T18 T19 T20

T13 T14 T15 T16T9 T10 T11 T12

T1 T2 T3 T4 T5 T6 T7 T8

The tolerance is 0.20 mm. Variation 0.07 mm is with in 75% of the Tolerance

Calculating Upper Control Limit


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R (Average of all Ranges) = 0.027 mm

(Rounded off to one decimal more than the data)

UCL = D4 x R

= 2.575 x 0.027 (D4 Value taken from table for 3 Sample Size)

= 0.0695 mm

Rounding off to the same decimal of data = 0.07 mm

Step 7: Checking the Consistency of Part to Part Variation


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20100

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0.00

Sample Number

SampleRa

nge

R Chart for Response

R=0.02731

UCL=0.07030

LCL=0

Checking the Consistency of Part to PartVariation


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Variation

1. All points lie with in the Limits

2. The Stratification level is > 3

3. There are no 7 points continuously increasing

4. There are no 7 points continuously decreasing

5. There are no 7 points in any of the 2 zones

ThereforePart to Part Variation is Consistent

Consistency of Part to Part Variation


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Checking the Consistency of Part to Part Variation (Step 7)

Average range (R-Bar) (Round off to onedecimal more than the data)

0.027Samples D3 D4

2 0 3.267

Upper control limit (UCL) = D4*R-Bar

(Round off to the same decimals as data)0.07

3 0 2.575

4 0 2.282

5 0 2.115

Lower control limit (LCL) = D3*R-Bar 0 6 0 2.004

Is the Part to Part Variation Consistent YES / NO

If the Part to Part variation is consistent, STOP, do not proceed further. Plan forDOE

Is the range chart plotted YES / NO

Are the stratification level more than 3 YES / NO

If the stratification level


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108

s

= Estimated Part to Part Variation

s= R/d2 (d2is a Constant and depends on Sample size.d2 for 3samples is 1.693)

= 0.027 / 1.693

= 0.0159 (To be rounded off to one decimal more than the data)

= 0.016

6s 0.096

Estimated Part to Part Variation Confidential level = 99.73%

Step 10 : Normality Check


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109

0.00-0.05-0.10

20

10

0

Response

Frequenc

y

Step 11 : Estimating Rejection Percentage


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110

Average 0.027 Z (usl) 4.563

s

0.016 Z (lsl) 7.938

6s 0.096Estimated Rejection

above USL0

USL 0.100Estimated Rejectionabove LSL

0

LSL -0.100 Cpk (usl) 1.521

Cpk (lsl) 2.646


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111

Variation Analysis forResponse to arrive at Control

method for Y


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112

Variation Analysis for

Response (Y)

Variation Analysis for Response (Y)Part Details


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113

Part Details

CharacteristicWall

thicknessPart Number 29320155/6 Gauge Number SM 200

Unit ofMeasurement

MM PartDescription

HousingMachining

GaugeDescription

VernierCaliper

Target Value Date 07.07.06Gauge Least

Count0.01 mm

Tolerance 1.00 mm

Gauge R&RValue 13%USL 5.80 mm

Study Dates& Shift

07.07.06

1stShift

LSL 4.80 mmAny other

details----

Data Grouping and Sample details

Number of Groups (Number of Time blocksx number of Streams)

26

Number of Samples in each group (It ispreferable to collect 5 samples continuously

from the process so that the inherentvariations are captured)

3

Study taken on Response at randomized time blocksActual time=3:26 Actual time=3:38 Actual time=3:48Actual time=3:05 Actual time=3:17 Actual time=4:04 Actual time=4:11 Actual time=4:21


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114


1 5.10 4 5.03 7 5.14 10 5.24 13 5.21 16 5.14 19 5.11 22 5.14

2 5.10 5 5.24 8 5.22 11 5.31 14 5.19 17 5.14 20 5.19 23 5.17

3 5.16 6 5.15 9 5.22 12 5.24 15 5.18 18 5.19 21 5.20 24 5.16


25 5.30 28 5.25 31 5.06 34 5.10 37 5.23 40 5.14 43 5.18 46 5.28

26 5.23 29 5.13 32 5.21 35 5.23 38 5.14 41 5.19 44 5.12 47 5.40

27 5.02 30 5.05 33 5.18 36 5.14 39 5.08 42 5.10 45 5.28 48 5.06


49 5.21 52 5.17 55 5.03 58 4.97 61 5.03 64 5.08 67 5.24 70 5.04

50 4.92 53 5.15 56 5.00 59 5.03 62 5.10 65 5.17 68 5.11 71 5.09

51 5.18 54 4.93 57 5.09 60 5.09 63 5.35 66 5.10 69 5.21 72 5.02


73 5.07 76 5.10

74 5.04 77 5.11

75 5.08 78 5.01

T17 T18 T19 T20 T21 T22

T6 T7 T8

T25 T26

T16T11 T12

T23 T24

T13 T14 T15

T1 T2 T3 T4

T9 T10

Actual time=4:28 Actual time=4:35 Actual time=4:45 Actual time=4:51

Actual time=6:56


T5


Actual time=5:33

Actual time=5:43 Actual time=5:56 Actual time=6:10 Actual time=6:20 Actual time=6:31 Actual time=6:38 Actual time=6:48

Time between Time blocks in Minutes

1) 12

2) 9

3) 12

4) 10

5) 16

6) 7

7) 10

8) 5

9) 9

10) 10

11) 6

12) 9

13) 8

14) 12

15) 13

16) 10

17) 13

18) 14

19) 10

20) 11

21) 7

22) 10

23) 8

24) 6

25) 10

Total = 247 mins = 4Hrs 7Mins

5.5

Randomised time block


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115

4.8

5.3

5.2

5.1

5.0

4.9

5.5

5.4

706560555045403530252015105 75 8580 1009590

T1 T5T4T3T2 T9T8T7T6

Re

sponse"Y"

Time interval in mins

Just before

event

Just after

event

Event

Time

T1 T2 T3 T4 T5 T6 T7 T8

Step 6: Checking whether the Part to Part is highest


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116


1 5.10 4 5.03 7 5.14 10 5.24 13 5.21 16 5.14 19 5.11 22 5.14

2 5.10 5 5.24 8 5.22 11 5.31 14 5.19 17 5.14 20 5.19 23 5.17

3 5.16 6 5.15 9 5.22 12 5.24 15 5.18 18 5.19 21 5.20 24 5.16

Ave 5.12 Ave 5.14 Ave 5.19 Ave 5.26 Ave 5.19 Ave 5.16 Ave 5.17 Ave 5.16

R 0.06 R 0.21 R 0.08 R 0.07 R 0.03 R 0.05 R 0.09 R 0.03


25 5.30 28 5.25 31 5.06 34 5.10 37 5.23 40 5.14 43 5.18 46 5.28

26 5.23 29 5.13 32 5.21 35 5.23 38 5.14 41 5.19 44 5.12 47 5.40

27 5.02 30 5.05 33 5.18 36 5.14 39 5.08 42 5.10 45 5.28 48 5.06


R 0.28 R 0.20 R 0.15 R 0.13 R 0.15 R 0.09 R 0.16 R 0.34


49 5.21 52 5.17 55 5.03 58 4.97 61 5.03 64 5.08 67 5.24 70 5.04

50 4.92 53 5.15 56 5.00 59 5.03 62 5.10 65 5.17 68 5.11 71 5.09

51 5.18 54 4.93 57 5.09 60 5.09 63 5.35 66 5.10 69 5.21 72 5.02


R 0.29 R 0.24 R 0.09 R 0.12 R 0.32 R 0.09 R 0.13 R 0.07


73 5.07 76 5.1

74 5.04 77 5.11

75 5.08 78 5.01

Ave 5.06 Ave 5.07

R 0.04 R 0.10

T9 T10 T11 T12 T13 T14 T15 T16

T23 T24T17 T18 T19 T20

T25 T26

T21 T22

# Part to Part Variation = Max. Value of R = 0.34

# Time to Time Variation = Max. Value of Ave.Min. Value of Ave. = 0.23

Part to Part variation is highestand hence we proceeded further

Calculating Upper Control Limit

R (A f ll R ) = 0 139


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117

R (Average of all Ranges) = 0.139 mm

(Rounded off to one decimal more than the data)

UCL = D4 x R

= 2.575 x 0.139 (D4 Value taken from table for 3 Sample Size)

= 0.3579

Rounding off to the same decimal of data = 0.36 mm

Step 7: Checking the Consistency of Part to PartVariation


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118

0 10 20

0.0

0.1

0.2

0.3

0.4

Sample Number

SampleRang

e

R Chart for response

R=0.1388

UCL=0.3574

LCL=0

Checking the Consistency of Part to Part Variation


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119

1. All points lie with in the Limits

2. The Stratification level is > 3

3. There are no 7 points continuously increasing

4. There are no 7 points continuously decreasing

5. There are no 7 points in any of the 2 zones

Therefore Part to Part Variation is Consistent

Consistency of Part to Part Variation



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120


Average range (R-Bar) (Round off to onedecimal more than the data)

0.139Samples D3 D4

2 0 3.267

Upper control limit (UCL) = D4*R-Bar

(Round off to the same decimals as data)0.36

3 0 2.575

4 0 2.282

5 0 2.115

Lower control limit (LCL) = D3*R-Bar 0 6 0 2.004

Is the Part to Part Variation Consistent YES / NO

If the Part to Part variation is consistent, STOP, do not proceed further. Plan forDOE

Is the range chart plotted YES / NO

Are the stratification level more than 3 YES / NO

If the stratification level


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121

s

= Estimated Part to Part Variation

s= R/d2 (d2is a Constant and depends on Sample size.d2 for 3samples is 1.693)

= 0.139 / 1.693

= 0.0821 (To be rounded off to one decimal more than the data)

= 0.082

6s= 0.492

Estimated Part to Part Variation Confidential level = 99.73%

Step 10 : Normality Check


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122

4.90 4.95 5.00 5.05 5.10 5.15 5.20 5.25 5.30 5.35 5.40

0

5

10

15

response

Frequenc

y

Step 11 : Estimating Rejection Percentage


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123

Average 5.141 Z (usl) 8.037

s

0.082 Z (lsl) 4.159

6s 0.492Estimated Rejection

above USL

0

USL 5.800Estimated Rejectionabove LSL

0

LSL 4.800 Cpk (usl) 2.679

Cpk (lsl) 1.390

Step 12 : Decision on the type of Monitoring

6 Analysis


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124

6s

Analysis

In our case Tolerance = 1.00 mm

6s= 0.492

6s


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125

Pre control limit for On job

Hour Wall thickness (Response)1stJob 2ndJob

1 5.33 5.11

2 5.41 5.61

3 5.28 5.39

4 5.14 5.26

5 5.09 5.06

6 5.45 5.51

7 5.12 5.25

8 5.47 5.21

Step 14 : On line Monitoring

Pre control limit for On job


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126

j

USL

UCL

LCL

LSL

Time interval

WallThickness(Response)inmm

5.80

5.30

5.55

5.05

4.80

5.000

4.85

4.95

4.90

5.65

5.70

5.60

5.50

5.45

5.405.35

5.25

5.20

5.15

5.10

5.75

1 2

43

5 6

7

8

Controls


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127

1. Drawing updated for new specification

2. Control plan updated

3. FMEA updated

4. The new parameters have been programmed and

locked in the system

5. A Setting Gauge has been introduced in milling

operation to check the new parameter settings at

periodical intervals.This has been incorporated in

Control plan and FMEA


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128

Control plan

Reaction Plan

Product Process

Product/Process

Specification

Tolerance

Evaluation/

Measurement

Technique

Sample Control

method Resp. Recording (Y/N)

CharacteristicsSpecial

Character

istic class

Methods

Control Plan


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129

Size Frequency

DISC 1.RADIUS DEPTH 133.7 0.30 MM CMM 1 PER DAY INSPECTIO INSPECTO YES HOLD,REINSPECT

MILLING

2.CENTER SHI FT OF 47.50 / 48.50 MM CMM 1 PER AY INSPECTIO INSPECTO YES HOLD,REINSPECT

RADIUS

3.CASTING LEVER DIAL 100% - INSPECTION QA NO SEGREGATE AND

DIMENSION AND FIXTURE KEEP

( TOOLING

LOCATION W.R.TO

CENTER OF

CASTING )

4.HARDNESS 165 - 250 BHN HARDNESS AS PER - INSPECTION QA NO SEGREGATE AND

MEASURING SHOWA KEEP

INSTRUMENT SINGLE

SAMPLING

PLAN

4.BUTTING OF VISUAL 100% - INSPECTION OPERATOR NO SEGREGATE AND

COMPONENT KEEP

5.CLAMPING PRESSURE ONCE PER DAY CHECKING OPERATOR YES INFORM

PRESSURE GAUGE MAINTENANCE

Tolerance Technique

Reaction Plan


Character

Methods

Product/Process Evaluation/

Control Plan


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130

Size Frequency

LUG 1.FLANGE 13.15 / 12.85 MM VERNIER 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

MILLING THICKNESS 11 GG 5092

2.POSITION FROM 11.5 MM VERNIER 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

HOLE CENTER

3.LUG FACE TO 24.20 / 23.80 MM HEIGHT GAUGE 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

"V" FACE S GD 7091 KEEP

4.CENTER SHIFT OF 47.50 / 48.50 MM S GV 7018 GAUG 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

RADIUS

Reaction Plan

Product Process Resp. Recording (Y/N)

Character

istic class

Product/Process

Specification

Tolerance

Evaluation/

Measurement

Technique

Sample Control

method

MethodsCharacteristicsSpecial

Control Plan


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131

Size Frequency

WALL 4.80 / 5.80 MM VERNIER 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

THICKN ESS

1.RADIUS DEPTH CMM 1 PER DA INSPECTIO OPERATOR YES HOLD,REINSPECT

2.CENTER SHIFT OF CMM 1 PER DAY INSPECTIO OPERATOR YES HOLD,REINSPECT

RADIUS



( SYMMENTRICITY )

5.CLAMPING PRESSURE ONCE PER DAY CHECKING OPERATOR YES INFORM

PRESSURE GAUGE MAINTENANCE

Control

methodResp. Recording (Y/N)

Reaction PlanSample

Product/Process

Specification

Tolerance

Evaluation/

Measurement

Technique

Special

Character

istic classProcessProduct


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132

Control plan &

Process FMEAafter 6 Sigma

Process FMEA after 6 Sigma

PROCESS


CURRENT PROCESS

CONTROL (TYPE - B)

CURRENT PROCESS

CONTROL (TYPE - C)

CURRENT PROCESS



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133

STEP CONTROL (TYPE - B) CONTROL (TYPE - C) CONTROL (TYPE - A)

DISC MILLING 1.DISC MILLING 1.HARDNESS 1 NIL RECEIVING INSPECTION NIL

RADIUS AS PER SHOWA SINGLE

OVERSIZE SAMPLING PLAN

UNDERSIZE ( ACCEPTANCE LEVEL 0 )

RESP : INSPECTOR

2.RADIUS DEPTH

OVERSIZE 2.CASTING DIMENSION NIL RECEIVING INSPECTION NIL

UNDERSIZE ( TOOLING LOCATION W.R AS PER SHOWA SINGLE

TO CENTER OF CASTING ) SAMPLING PLAN

3.CENTER SHIFT ( ACCEPTANCE LEVEL 0 )

OF RADIUS RESP : INSPECTOR

OVERSIZE

UNDERSIZE 3.BUTTING THE CASTING NIL POKA - YOKE ONCE IN 2 HRS BY QA 6 6

BY OPERATOR PROVIDED PRE-DESPATCH

INSPECTION

AS PER SHOWA SINGLE

SAMPLING PLAN


RESP : INSPECTOR

4.TABLE MOVEMENT NIL IT IS IN PM CHECK NIL

LIST

PROCESSFAILURE MODE POTENTIAL CAUSES OCC

CURRENT PROCESS CURRENT PROCESS CURRENT PROCESSDET RPN

Process FMEA after 6 Sigma


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134


CONTROL (TYPE - B) CONTROL (TYPE - C) CONTROL (TYPE - A)DET RPN

LUG FLANGE 1.CENTER SHIFT OF RADIU 1 PROCESS CONTROL NIL ONCE IN 2 HRS BY QA 6 6

MILLING THICKNESS CHART PRE-DESPATCH

VARIATION CHECK 1 NO/HOUR INSPECTION

RESP: OPERATOR AS PER SHOWA SINGLE

SAMPLING PLAN


INSPECTOR

2.SPINDLE AXIAL AND NIL ADDEED IN THE

RADIAL PLAY PM CHECK LIST

Process FMEA after 6 SigmaPROCESS


CURRENT PROCESS

CONTROL (TYPE - B)

CURRENT PROCESS

CONTROL (TYPE - C)

CURRENT PROCESS



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135

PIN HOLE WALL 1.CASTING DIMENSION 1 NIL RECEIVING INSPECTION NIL 6

DRILLING THICKNESS ( SYMMETRICITY, AS P ER SHOW A SINGLE

UNDERSIZE CAVITY TO CAVITY & SAMPLING PLAN

BOSS DIAMETER ) ( ACCEPTANCE LEVEL 0 )

RESP : INSPECTOR

2.RADIUS DEPTH PROCESS CONTROL NIL ONCE IN 2 HRS BY QA 5 5

CHART PRE-DESPATCH

CHECK 1 NO/HOUR INSPECTION

RESP : INSPECTOR AS PER SHOWA SINGLE

SAMPLING PLAN

3.CENTER SHIFT OF PROCESS CONTROL NIL ( ACCEPTANCE LEVEL 0 )

RADIUS CHART RESP : INSPECTOR

CHECK 1 NO/HOUR

RESP : INSPECTOR

Size Frequency

Special

Character

istic class

Methods

Reaction Plan

Product Process

Product/Process

Specification

Tolerance

Evaluation/

Measurement

Technique

Sample Control

method Resp. Recording (Y/N)

Characteristics

Control Plan after

6 Sigma


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136

Size Frequency

DISC 1.RADIUS DEPTH 133.55 / 133.67 MM S GV 7018 GAU 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

MILLING (PROCESS)

2.CENTER SHIFT OF 48.17 / 48.37 MM S GV 7018 GAU 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

RADIUS (PROCESS)



( TOOLING

LOCATION W.R.TO

CENTER OF

CASTING )

4.HARDNESS 165 - 250 BHN HARDNESS AS PER - INSPECTION QA NO SEGREGATE AND

MEASURING SHOWA KEEP

INSTRUMENT SINGLE

SAMPLING

PLAN

Sample ControlReaction Plan


Character

Methods

Product/Process Evaluation/

Control Plan after 6 Sigma


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137

Size Frequency

LUG 1.FLANGE 13.15 / 12.85 MM VERNIER 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

MILLING THICKNESS 11 GG 5092

2.POSITION FROM 11.5 MM VERNIER 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

HOLE CENTER

3.LUG FACE TO 24.20 / 23.80 MM HEIGHT GAUGE 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

"V" FACE S GD 7091 KEEP

4.CENTER SHIFT OF 48.17 / 48.37 MM S GV 7018 GAUG 1 PER HOUR INSPECTIO OPERATOR YES HOLD,REINSPECT

RADIUS (PROCESS)

Sample Control

methodProduct Process Resp. Recording (Y/N)istic class Specification

Tolerance

Measurement

Technique

Control Plan after 6 Sigma

MethodsCharacteristics


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138

Size Frequenc

WALL 4.80 / 5.80 MM VERNIER 1 PER HOUR INSPECTIO OPERATOR YES

THICKNESS S GG 7167

1.RADIUS DEPTH S GV 7018 GAUGE 1 PER HOUR INSPECTIO OPERATOR YES

2.CENTER SHIFT OF S GV 7018 GAUGE 1 PER HOUR INSPECTIO OPERATOR YES

RADIUS

3.CASTING LEVER DIAL AS PER - INSPECTION QA NO

DIMENSION AND FIXTURE SAMPLING

( SYMMENTRICITY )

Recording (Y/N)

MethodsCharacteristics

Product/Process

Specification

Tolerance

Evaluation/

Measurement

Technique

Special

Character

istic classProcessProductSample Control

methodResp.

HOLD,REINSPECT

HOLD,REINSPECT

HOLD,REINSPECT

SEGREGATE AND

KEEP

Reaction Plan



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139

Phase Tools

Control 1. Variation Analysis

2. Pre-Control chart3. Control plan

BenefitsRejection reduced to Zero


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140

Rejection due to M/H Less Wall thickness

000000

67

5

001

2

3

4

56

7

8

Week36

Week37

Week38

Week39

Week40

Week41

Week42

Week43

Week44

Week45

QtyinNos

Improvement

through 6s

Qty Produced from week 39 week 45

= 39785 Nos

Estimated Cost Saving by Rejection reduction is Rs. 1,21,589 / Annum


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Documents

Six Sigma Project - Brakes India - Wall Thickness Variation