Application of Design of Experiments (DOE) using Dr.Taguchi -Orthogonal Array in Manufacturing...

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PREPARED BY K.KARTHIKEYAN 1

DOE

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DOE PROJECT TITLE

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3PREPARED BY K.KARTHIKEYAN

DOE

1.1 Problem Statement

High flash fail rejections in manufacturing line

1.0 PROBLEM SELECTION

What is Flash fail rejections?

It is the insulation failure between armature core and

copper wire coil wound on the armature core. This is

being checked in manufacturing line.

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1.2 Why this Problem is important ?

� Flash fail rejection is top in Pareto in manufacturing line

rejection.

� This will resulting increase scrap value and if not detected

during testing stage can results customer line rejection and

warranty return.

1.3 Theme

To Reduce the manufacturing line rejection.

1.4 Target

Elimination of flash fail rejection in armature before Wk No.15.


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1.5 Action Plan

STEP

P

A

P

A

P

A

P

A

P

A

P

A

P

A

Planned - Actual -

WK NO.15WK NO.13

Problem selection

Observation

WK NO.14WK NO.10 WK NO.11 WK NO.12

Conclusion

Analysis

Action

Check

Standardisation


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0.194 0.182 0.192 0.186 0.188 0.194

0.143 0.1450.135 0.137 0.143 0.141

0

0.05

0.1

0.15

0.2

0.25

WK4 WK5 WK6 WK7 WK8 WK9

% Rejection

Week

2.0 OBSERVATION

Armature average rejection – 0.19 %

Average Flash fail rejection – 0.14 %

� Average manufacturing line rejection was 1900 ppm ( From week

No.4 to 9) and Flash fail alone average rejection was 1400 ppm.

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MANUFACTURING REJECTION - PARETO

2.0 OBSERVATION

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3.0 ANALYSIS :

3.1 Defective analysis - Concentration chart:

The study of defectives shown all flash fail are due to defective powder coating and

wire touching core. A concentration chart diagram of defective shows no

concentration of defects

3.0 ANALYSIS

3.2 Comparing of Good & Bad sample:

In all bad samples the coating thickness found less than specification of 300 - 400

microns

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Gap between

Coil & Armature

3.3 CAUSE AND EFFECT DIAGRAMA cause & effect diagram was constructed depicting the various probable causes.

Powder

Coating

thickness

Variation

MAN MATERIAL

Sop not adequate

OD clean belt

MACHINEMETHOD

Pre Heating

Temp

Lumps in Powder

Air Knife pressure

Component

orientation Process parameter

Masking JIG

MEASUREMENT

Coating Thickness

not Checked

properly

Not given in drawing

Humidity in powderJig not properly seated

Lack of training

Voltage Coater Pr

Uneven fluidization

Program selection

Cleaning method

Powder Storage

level

Cu Plate

Curing

tempENVIRONMENT

Humidity

Powder Storage

Room temp

Untrained

Operator

Fatigue

Shell life completed

Rust on Core

Conveyor

Speed

3.0 ANALYSIS

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1. Objective of the experiment

2. Selection of factors, levels and expected interactions

3. Selection of experimental design

4. Experimental preparation and randomize the Experimental run

5. Statistical data analysis

6. Experimental Conclusions and recommendations

4.0 STEPS FOR DESIGN OF EXPERIMENT

• ALL THE POSSIBLE CAUSES ARE INVALID. IT IS VERY DIFFCULT TO CHECK

PROBABLE CAUSE HENCE WE DECIDED TO DO DOE TO OPTIMIZE PROCESS

PARAMETER IN POWDER COATING PROCESS BY USING TAGUCHI METHOD.

3.0 ANALYSIS

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The Powder Coating process having the following 14 process parameters

2.0 Selection of factors and expected interactions and Response

DESIGN OF EXPERIMENT

To optimize the Powder Coating process parameters through Taguchi method.

1.0 Objective of the experiment:

Sl.No Parameter

1 Conveyor Speed (Hz)

2 Electrostatic Voltage (kV)

3 Sub coater pressure (Mpa)

4 Coater Pressure (Mpa)

5 Powder feeder Pressure (Mpa)

6 Air hopper Pressure(Mpa)

7 OD removal belt height (mm)

8 Air Knife 1 (Mpa)

9 Air Knife 2 (Mpa)

10 Air Knife 3 (Mpa)



13 Pre heating temperature (oC)

14 Curing temperature (oC)

Sl.No Parameter

1 Conveyor Speed

2 Electrostatic Voltage

3Preheating

Temperature

4 Curing Temperature

5 Coater Pressure

Our team has selected all five key

process parameter to optimize the

powder coating process based on

the Experience and knowledge.

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A. Conveyor Speed in Hz ( 15 Hz)

B. Electrostatic voltage in kV (60 kV)

C. Preheating temperature in O C (150O c)

D. Curing temperature in O C ( 240O c )

E. Coater pressure in bar ( 0.05 bar)

2.a Choice of Main Factors

2.b. Interaction of Interest:

1. Conveyor speed & Coater pressure (A & E)

2. Electrostatic voltage & Coater pressure (B & E)

3. Preheating temp & Coater pressure (C & E)

4. Curing temp & Coater pressure (D & E)


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2.c.Choice of factor levels

Three levels selected for each factors based on experience & knowledge

Level 1 , Level 2 , Level 3

Replication = 5 Nos

Factors Level 1 Level 2 Level 3

Conveyor speed (Hz) 15 16 17

Electrostatic Voltage (kV) 50 55 60

Preheating temperature ('C) 150 180 210

Curing temperature ('C) 240 280 320

Coater Pressure (bar) 0.03 0.05 0.08

Factors SpecficationExisting

Setting

Conveyor speed (Hz) 15 15

Electrostatic Voltage

(kV)55 ±5 60

Preheating temperature

('C)180±20°C 150

Curing temperature ('C) 280±40°C 240

Coater Pressure (bar) 0.05±0.02 0.05

2.d. Selection of Response

Coating thickness in Armature ( Spec: 300 – 400 microns)


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Total no of Factors 5 and 4 Interactions with 3 levels

3.1. Required Degree of freedom for main factor

= (No of levels - 1) X No of factors = (3 - 1) X 5 = 10

3.2. Required Degree of freedom for Interaction

= ((DOF of A X DOF of E) + (DOF of B X DOF of E)

+ (DOF of C X DOF of E) +( DOF of D X DOF of E) )

= ((3 - 1) X(3 – 1))+((3 - 1) X (3 - 1))+((3 - 1) X (3 - 1) )+( (3 - 1) X (3 - 1))

= 16

3. Selection of Experimental Design:


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3.3.Total Degrees of freedom = DOF of Main effect + DOF of Interaction

= 10 + 16

= 26

3.4.Minimum no of Experiments = Total Degrees of Freedom + 1

= 26 + 1

= 27

3.5.Suitable Orthogonal Array

from Table

= L27

(3) 13


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3.6. Required Linear graph:

3.7. Standard Linear graph (Select from orthogonal table):

A

E B

C

D

B X E

A X E

D X E

C X E

1

5 2

910

76

1183

12413

1

5 2

910

76

1183

12413


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3.8. Modified Standard Linear graph

� Assignment of factors is done using the Linear graph

� Nodes – factors

� Lines – interaction between factors

1

(A)

2

(B)

9

(C)

10

(D)

6 7 (AXE)

8 11 (BXE)

4 12 (DXE)

3 13 (CXE)

5

(E)


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3.9. Draw Design Layout of Experiment: (From OA table) = L27 Array


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FACTORS AND LEVELS FOR THE EXPERIMENTS

1. A – Conveyor Speed in HZ

2. B – Electrostatic Voltage kV

9. C - Preheating Temperature °C

10. D - Curing Temperature °C

5. E – Coater Pressure in bar

6 7. Conveyor Speed in HZ X Coater Pressure in bar ( AXE)

8 11. Electrostatic Voltage kV X Coater Pressure in bar (BXE)

3 13. Preheating Temperature °C X Coater Pressure in bar (CXE)

4 12. Curing Temperature °C X Coater Pressure in bar (DXE)


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3.10 Physical Layout of Experimentation:


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4. 0 Experimental run Result:


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171615

340

330

320

605550 210180150

320280240

340

330

320

0.080.050.03

Conveyor speed

Mean of Means

Electrostatic v o ltage Preheating temp

Curing Temp Coater pressure

Main Effects Plot for MeansData Means

Interpretation

A2,B1,C2,D2, & E1

are best levels

AVERAGE RESPONSE GRAPHS OF MAIN EFFECTS

Interpretation of Experimental trials

5.0 Analysis and Interpretation of Experimental trials:

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AVERAGE RESPONSE GRAPHS OF INTERACTION EFFECTS

Interpretation : Electrostatic Voltage x Coater pressure, Preheating Temperature x

Coater pressure, Curing Temperature x Coater pressure interactions are exists

350

330

310

605550 320280240

350

330

310

0.080.050.03

350

330

310

350

330

310

171615

350

330

310

210180150

Conveyor speed

Electrostatic voltage

Preheating temp

Curing Temp

Coater pressure

15

16

17

speed

Conveyor

50

55

60

voltage

Electrostatic

150

180

210

temp

Preheating

240

280

320

Temp

Curing

0.03

0.05

0.08

pressure

Coater

Interaction Plot for MeansData Means


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SELECTION OF OPTIMUM COMBINATION (BASED ON MAIN EFFECT

PLOT AND INTERACTION EFFECT PLOT)

The best combination is

A2 B1 C2 D2 & E1

The best levels of individual factors are


Conveyor speed (Hz) 15 16 17

Electrostatic Voltage (kV) 50 55 60

Preheating temperature ('C) 150 180 210

Curing temperature ('C) 240 280 320

Coater Pressure (bar) 0.03 0.05 0.08


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If the ‘F Calculated ’ value is greater than ‘ F Table’ value or p value

is less tan 0.05 then that factor shall be considered as significant.

If the ‘F Calculated ’ value is greater than ‘ F Table’ value or p value

is less tan 0.05 then that factor shall be considered as significant.INTERPRETATIONINTERPRETATION

5. Interpretation through ANOVA Method:

DOFSum of Square

MSS F cal F Table P value % ContResult

(Fcal > F Tab

2 65.80 32.90 0.152 3.080 0.859 0.1 Not Significant

2 14062.40 7031.20 32.425 3.080 0.000 25.5 Significant

2 557.60 278.80 1.286 3.080 0.281 1.0 Not Significant

2 6355.70 3177.85 14.655 3.080 0.000 11.5 Significant

2 1630.90 815.45 3.761 3.080 0.026 3.0 Significant

4 2247.20 561.80 2.591 2.455 0.041 4.1 Significant

4 817.90 204.48 0.943 2.455 0.442 1.5 Not Significant

4 3747.00 936.75 4.320 2.455 0.003 6.8 Significant

4 2321.100 580.275 2.676 2.455 0.036 4.2 Significant

108 23419.00 216.84 42.4

134 55225.00 100

Error

Total

Curing temp x coater pressure (DXE)

Conveyor speed x coater pressure (AXE)

Electrostatic voltage x coater pressure (BXE)

Coater Pressure bar (E)

Conveyor speed - Hz (A)

Electrostatic voltage Kv -(B)

Preheating temp x Coater pressure (CXE)

Factors

Preheating temperature °C ('C)

Curing temperature °C (D)

Interpretation through ANOVA

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INFERENCE ON ANOVA:

Interpretation Of ANOVA Based On P-Value

Based on the P Value from the ANOVA table the following are the inferences. The

details Of Individual Factor Significance And Significance of interaction were given

below.


A Conveyor speed (Hz) 15 16 17

B Electrostatic Voltage (kV) 50 55 60

C Preheating temperature ('C) 150 180 210

D Curing temperature ('C) 240 280 320

E Coater Pressure (bar) 0.03 0.05 0.08

1. Factor A - Insignificant

2. Factor B - Significant

3. Factor C - Insignificant

4. Factor D - Significant

5. Factor E - Significant

6. InteractionA X E - Significant

7. Interaction B X E - Insignificant

8. Interaction C X E - Significant

9. Interaction D X E - Significant

Interpretation through ANOVA

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DOE 4.0 ACTION

FactorsPrevious

setting

Optimized

setting

A Conveyor speed in rpm 15 16

B Electrostatic voltage in kV 60 50

C Pre heat temperature in o C 150 180

D Curing temperature in o C 240 280

E Coater pressure in bar 0.05 0.03

� From the Experiment the Armature powder coating process

parameters are optimized.

RECOMMENDED (OPTIMISED) PRODUCTION SETTING

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Based on the best optimum combination obtained from the results

of experiments a confirmatory run has been done and the results

were verified with the predicted values and found well near to the

values.

30 Nos.of samples taken for the optimum level and Cpk values

were recorded and the same values were interpreted.

CONFIRMATORY TRIAL WITH PREDICTED VALUES

4.0 ACTION

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CONFIRMATORY TRIAL

5.0 CHECK

Before DOE : 1.07 After DOE : 1.27

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REJECTION TREND (After Improvements)

5.0 CHECK

6.0 STANDARDISATION

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> From the Design of Experiment analysis, powder

coating process parameter is optimized as per the

below process setting and it is clearly indicates that

the Powder coating process is well within the process

center.

7.0 CONCLUSION

> Thus by improving the Cpk of Powder coating process

Armature manufacturing line rejection reduced from 1900 PPM

to 700 PPM. Flash fail rejections reduced from 1400 PPM to 200

PPM

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Application of Design of Experiments (DOE) using Dr.Taguchi -Orthogonal Array in Manufacturing...

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