Caso 6 Sigma - Case Study-1

7/30/2019 Caso 6 Sigma - Case Study-1

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Shainin DOE, Version: 1.1,J an03

1ACMA ACT

Six Sigma BB Project


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2ACMA ACT

Project Number : 01

Project Description

Bore Diameter 35 mm Unclean

in Throttle Body AC-35.

Six Sigma BB Project


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3ACMA ACT

DOE Project Description

Name of BB - Mr. Arvind Gupta (ACMA-ACT)

Team members - Mr. N.Prakash, Mr.I.P. Batra (UCALFuel Systems Limited,Gurgaon)

Annual Cost Of Poor Quality: Rs, 1,78,610/-

Project reference: 001/04 -05

Date of Start : 20/07/04

Phases Compl.

Date

Phase-1 20-07-04

Phase-2 22-07-04

Phase-3 03-08-04Phase-4 10-08-04


4/32Shainin DOE, Version: 1.1,J an03

4ACMA ACT

DOE Project

Cost of Poor Quality Breakup

Rework Cost : NIL

Machining Cost : Rs 56,448/-

Raw Material Cost : Rs.1,22,162/-

Intangible Savings1. Internal Customer Satisfaction.

2. Smooth flow of products.3. Learning of Systematic Approach to solve the problem.

4. Breakthrough in the company towards the attitude.



5ACMA ACT

Phase 1- Definition

Problem definition - Bore Unclean-(reduced from 0.56 % to ZERO.)

Response definition - Attribute

Instrument to be used - Visual

R&R study details -Not Required

Potential SSVs from

FMEAs\ Brain storming Brain storming



6ACMA ACT

Phase-1- Definition

Problem & Response Definition

Problem Statement- Bore diameter 35 mm unclean in Throttle Body AC-35.

Response to be measured- Bore Unclean ( Attribute)

Specification-No Unclean

Instrument used to verify the Response- Visual

Least Count of the instrument-Not Applicable



7ACMA ACT

Phase 1 Definition

R&R study details

Is R&R study required for the Measurement

system -No

Result of R&R study

% E.V. -Not Applicable

% A.V. -Not Applicable

% R & R -Not Applicable

Ph 1 D fi i i



8ACMA ACT

Phase 1 Definition

Listing Potential Source of Variation

Y = f (X)Where Y= Response ( Unclean in Bore)

X = Suspected Source of Variation (SSV)

SSVs are:1. Mounting Hole Dia. 6.5 +0.2/+0

2. Mounting Hole Position w.r.t. Bore (X axis) 24 +/- 0.05

3. Mounting Hole Position w.r.t. Bore (Y axis) 28+/- 0.05

4. Mounting Face Flatness 0.05 Max

5. Step in Bore Diameter35 at Casting Stage .

Ph 1 D fi iti



9ACMA ACT

Phase 1 Definition

Drawing/Photograph

Throttle Body

35 Bore

Unclean

Mounting Face

0.05 max.

Locating HolesDia 6.5+0.2/0.0

24 +/- 0.05

28 +/-0.05

Ph 1 D fi iti



10ACMA ACT

Phase 1 Definition

Drawing/Photograph

Throttle Valve

Throttle Body

Sensor Bracket

Ph 1 D fi iti



11ACMA ACT

Phase 1 Definition

Drawing/Photograph

Locating Pins Clamp

Boring BarFixture



12ACMA ACT

Phase 2 Measure and Analyze

Shainin DOE Tool selection - Paired Comparison

Data collection - Yes

Analysis of Data - Yes

Conclusion based on data - Yes

Ph 2 M d A l



13ACMA ACT

Phase2 Measure and Analyze

Tool selection

Initial Tool selected

Since the SSVs- Mounting Holes Diameter 6.5 mm

, Hole Positions w.r.t Bore center ( x & y co-ordinates) 24 & 28 mm and Mounting Face Flatness

can be checked on Good & Bad Parts both , D.O.E.

Tool selected was Paired Comparison.


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14ACMA ACT


Data Collection

Good andBadparts selected based on the Response( Bore

unclean)

8 Best of Best (Good) and8 Worst of Worst (Bad)parts

selected based on the Response.

SSVs Dimension 28+/- 0.05 , 24 +/-0.05 , Hole Size 6.5 +0.2/-0 &

Flatness of mounting face 0.05 max. measured on both Good and

Badparts and analyzed for the counts.



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15ACMA ACT

S.N. Dimn 28+/-0.05 Result S.N. Dimn 28

+/-0.05 Result

1 27.95 G 1 27.93 B

2 27.95 G 2 27.94 B3 27.96 G 3 27.96 G

4 27.96 G 4 27.97 G

5 27.96 G 5 27.98 B

6 27.96 B 6 27.99 B

7 27.97 G 7 28.00 B

8 27.97 B 8 28.00 B

9 27.97 B 9 28.01 B

10 27.97 G 10 28.03 G

11 28.03 B 11 28.04 G

12 28.03 B 12 28.05 B

13 28.04 B 13 28.05 G

14 28.05 B 14 28.06 G

15 28.06 B 15 28.06 G

16 28.06 G 16 28.06 G

COUNT = ZERO COUNT = 5.5


Data Collection and analysis

Hole -

1

Hole -

2

Not A

Cause

Not A

Cause



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16ACMA ACT

S.N. Dimn 24+/-0.05 Result S.N. Dimn 24+/-0.05 Result

1 23.94 B 1 23.97 B2 23.95 B 2 23.97 B

3 23.95 B 3 23.98 B

4 23.95 G 4 23.99 B

5 23.95 B 5 24.00 B

6 23.95 B 6 24.01 B

7 23.96 B 7 24.03 B

8 23.96 B 8 24.05 B

9 23.97 G 9 24.05 G

10 23.97 G 10 24.05 G

11 23.97 G 11 24.05 G

12 23.98 B 12 24.05 G

13 23.99 G 13 24.05 G

14 24.00 G 14 24.06 G

15 24.00 G 15 24.07 G

16 24.03 G 16 24.07 G

COUNT = 5 COUNT = 10

Hole -1

Hole -2



Not A

Cause

One of

the

Cause



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17ACMA ACT

S.N.Hole Dia 6.5

+0.2/-

0.0Result S.N.

Hole Dia 6.5+0.2/-

0.0Result

1 6.61 B 1 6.62 B

2 6.62 B 2 6.62 B

3 6.63 B 3 6.62 B

4 6.63 B 4 6.63 B

5 6.63 B 5 6.63 B

6 6.64 B 6 6.63 B7 6.64 B 7 6.65 B

8 6.64 B 8 6.66 B

9 6.66 G 9 6.66 G

10 6.66 G 10 6.66 G

11 6.66 G 11 6.66 G

12 6.66 G 12 6.67 G

13 6.66 G 13 6.67 G

14 6.66 G 14 6.67 G

15 6.67 G 15 6.67 G

16 6.67 G 16 6.67 G

COUNT = 16 COUNT = 12

DATA COLLECTION FOR SSV'S



Hole -

1

Hole -

2

RootCause Root

Cause



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18ACMA ACT

S.N.

Flatness of

Mounting Face

0.05 Max.

Result

1 0.020 G

2 0.020 G

3 0.025 B

4 0.025 G

5 0.025 G

6 0.026 G

7 0.028 B

8 0.028 G

9 0.030 B

10 0.035 G

11 0.035 B

12 0.038 B

13 0.040 B

14 0.042 B

15 0.045 B

16 0.050 G

COUNT = ZERO

Phase 2 Measure and AnalyzeData Collection and analysis

Not A

Cause



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19ACMA ACT

S.N.

Hole Dia 6.5+0.2/-

0.0 Result

1 6.61 B

2 6.62 B

3 6.63 B

4 6.63 B

5 6.63 B6 6.64 B

7 6.64 B

8 6.64 B

9 6.66 G

10 6.66 G

11 6.66 G

12 6.66 G

13 6.66 G

14 6.66 G

15 6.67 G

16 6.67 G

Analysis:


Since the count is=16, Mounting

Hole size Dia 6 mm

is one of the

strongest

cause of theproblem



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20ACMA ACT

S.N.Hole Dia 6.5

+0.2/-

0.0Result

1 6.61 B

2 6.62 B

3 6.63 B

4 6.63 B

5 6.63 B

6 6.64 B7 6.64 B

8 6.64 B

9 6.66 G

10 6.66 G

11 6.66 G

12 6.66 G

13 6.66 G

14 6.66 G

15 6.67 G

16 6.67 G

COUNT = 16

Conclusions:


Inference from the dataGOOD ---6.66 ~ 6.67 mm

BAD------6.61 ~ 6.64 mmDrg. Spec. 6.50~6.70mm

Variation in the Process

6.61 ~ 6.67 = 0.06 mm(within Spec.)

Locating Pin size---6.57mmClearance between Pin and

locating hole

GOOD

Max.6.67-6.57=0.1mm

Min.6.66-6.57=0.09mmBAD

Max.6.64-6.57=0.07mm

Min 6.61-6.57= 0.04mm


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21ACMA ACT

Phase 3 Improvement

Conclusions ( Root Cause):

From the analysis ,it is evident that clearance between

Locating Pin & Mounting hole varying from 0.09 to 0.1result in GOOD Product wherein clearance rangingbetween 0.04 to 0.07 mm result in BAD product.

So we need to maintain the clearance between Pin &

Hole min 0.09 mm.


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22ACMA ACT

Phase 3 Improvement

Opportunities available

Option No.1:To Change the Spec of Hole Size from present 6.5+0.2 to6.66+0.06mm ( To maintain min clearance 0.09) which requires drillsize change & also sought approval from customer as the drawing is

customer approved. Subsequent fitment at the customer end wasalso a constraint, so Option no.1 was ruled out.

Option no.2 : To modified the Pin size from present 6.57 to 6.52 to

maintain minimum clearance of 0.09 mm ( As per data for GOOD

parts).Option -2 ,Implemented.


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23ACMA ACT

Phase 3 Improvement

After the countermeasure taken, 100 %inspection of the parts carried out visually on

the machine for bore unclean problem.

Rejection found to be

ZERO out of total 15,000parts made till now.


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24ACMA ACT

Phase 4 - Control

Tool drawing Has been modified & standardizedfor the locating pin size 6.57 to 6.52 mm.

FMEA has been updated.

Control Plan( maintenance) has been revised forthe pin change frequency.


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25ACMA ACT

Phase 4 - Control

MATERIAL :EN 31

HARDNESS :40~50HRC

QUANTITY :1 NOS

ALL SHARP

CORNERS TO BE

CHAMFERED


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26ACMA ACT

Bore Unclean

Paired Comparison

DOE TOOL

DOE TOOL

0

10

2030

40

50

60

70

80

90

1 st Q tr 2 nd Qt r 3r d Qt r 4 th Q tr

East

West

North

FUNNELING BY 6 SIGMA


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27ACMA ACT

Phase 4 - Control

Variation analysis:

Since the variation in the hole size is less than 50 % of the

tolerance,Pre-control chart has been implemented on themachine to record the variation in the hole size due to drill worn

out at hole drilling stage.


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28ACMA ACT

Phase 4 - Control

Scatter plot has been introduced on the machine to

record theno .of parts produced and the variation in

hole size to find out (optimize) Tool ( drill ) Life.


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29ACMA ACT

Horizontal Deployment

Throttle Body AC-38

Phase 4 - Control


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30ACMA ACT

Phase 4 - Control

Although problem now seems to be easy ,but it was

difficult in the beginning to find out the root cause of the

problem as generally it is perceived that more clearancebetween hole & pin will cause the problem whereas in

this case , it was a case of less clearance causing the

problem.

Learning:

To avoid the twist of the part while mounting on to thefixture ,Min clearance between the locating pin & hole

shall be kept 0.1 mmapprox( Subject to fitment and function of

the part).


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31ACMA ACT

Project Completed


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32ACMA ACT

Documents

Caso 6 Sigma - Case Study-1