2 power one

Andrea GrilliQuality EngineerSustain Engineer

Lean Six Sigma Green Belt

Master FESTO Academy 10°ed. 2012

Quality Department

Power-One Italy S.p.A.

2013 March 26th

(Minitab Convention reviewed. May 2013)

FTY improvement(PVI-3KW area)

| | | | CONFIDENTIALCONFIDENTIALCONFIDENTIALCONFIDENTIAL

PVI-3KW family: PVI-3.0, PVI-3.6, PVI-4.2The most common residential inverter is the ideal size for an average-sized

family home. This single-phase string inverter complements the typical number

of rooftop solar panels, allowing home-owners to get the most efficient energy

harvesting for the size of the property.

This rugged outdoor inverter has been designed as a completely sealed unit to

withstand the harshest environmental conditions. One of the key benefits of this

inverter is the dual input section to process two strings with independent MPPT

especially useful for rooftop installations with two different orientations (ie East

and West). The high speed MPPT offers real-time power tracking and improved

energy harvesting. The transformer-less operation gives the highest efficiency of

up to 96.8% (>95%; MEAN 96%). The wide input voltage range makes the

inverter suitable to low power installations with reduced string size.

Available in the following countries:

Australia – Belgium – China – Greece - Ireland

Israel – Portugal – Spain - Czech Republic

France – Germany – Hungary - Italy

Spain - United Kingdom - United States

Product Presentation

2 of 29


Business Case Team

In PVI-3KW [PVI-3.0KW, PVI-3.6KW, PVI-4.2KW] production area we have

a low rate of FTY%. This condition leads to negative economic results.

Leader: Andrea Grilli

Champion: Luciano Raviola

Problem Statement Coach: Giuseppe Mangano (BB)

The weekly rate of FTY% during year 2012 is low. In the last production

Month October 2012, FTY% was 88.8%.

Up to now we were focused on the fails gone through repair area with no

consideration of test Operator self-repair units; ATE inefficiencies; ATE

operator wrong operation; re-tested units.

Members: Paolo Donzellini (Testing)

Claudio Serboli (Mngr Mfg)

Letizia Badii (Ripair)

Luca Scala (IE)

Samanta Marzielli (QC)

Vincenzo Russino (R&D)

Project Scope (In-Out) Target

In scope

The Team will be focused on the October 2012 production data collection

as representative and significant sample of the entire year. All kind of

fails will be included in the analysis.

Out of scope

Fails for problems already under analysis at the beginning of this project.

Estimated Soft saving:

Employee at repair station will work part time to other jobs.

Estimated Hard Saving:

Increasing to 93% FTY rate will allow:

Remove two temporary employees at ATE.

Reduce cost for scrap components.

Reduce overtime work.

40.000€ per year starting from April 2013.

Milestones

D 29-11-2012 (Closed)

M 17-12-2012 (Closed)

A 18-01-2013 (Closed)

I 15-02-2013 (Closed)

C 20-03-2013 (Closed)

Project Charter

DEFINE MEASUREMEASURE ANALYZEANALYZE IMPROVEIMPROVE CONTROLCONTROL

3 of 29


VOC: Increase FTY% in the «PVI-3KW» Department

��% �#��

#�� 100 ��% �

#��

#�� 100

Increase FTY Reduce total defects=

CTQ: FAIL %

VOC (Voice of the Customer) and CTQ (critical to quality)

DEFINE MEASUREMEASURE ANALYZEANALYZE IMPROVEIMPROVE CONTROLCONTROL

4 of 29


SSupplier

IInput

PProcess

OOutput

CCustomer

Internal\ External semi-finished

products Suppliers

Discrete component Supplier

Assembled PVI

VDR

Labels, Manuals

Mechanical parts

Packaging Company

Power-one

Compliant PVIs

Data Collection

Scrap

! Basic Process Flow diagram

SIPOC-process mapping (As Is)

DEFINE MEASUREMEASURE IMPROVEIMPROVE CONTROLCONTROL

5

ANALYZEANALYZE

of 29


Test Line process mapping – ASME logic diagram (As Is)

DEFINE MEASUREMEASURE IMPROVEIMPROVE CONTROLCONTROL

BI

BURN-IN

RST

RESET TEST

OPOPOPOP

Burn-In

Deposit

OP

HP

SAFETY -TEST

OP

Take

label

Label Assembly

CAL

ATE 4 VDR Assembly

OP

Take

2 VDRs

INSP

AC Cable

connection

DC PAD

connection

RS485 cable

connection

Protection

install

AC Cable

screwing

AC Cable

connection

DC PAD

connectionAC Cable

screwing

OP

AC Cable

connection

DC PAD

connection

RS485 cable

connection

Protection

installBar-code

reading AC Cable

screwing

AUX BUS

Cable

connection

USB

Cable

Connection

FT

ATE

OPOP

OP

OP

ASSEMBLY LINE

FT OPERATOR

PHASES

CAL OPERATOR

PHASES

INSP

OP

AC Cable

connection

DC PAD

connection

AC Cable

screwing

OP

OP OP

DC PAD

connection

Bar-code

reading

OP

Dc cable assembly

Take

2 VDRs

6

ANALYZEANALYZE

of 29


!One Repair Station for 12

ATES and inspection phases

Repair process mapping – Flow diagram

MUDA

!One Quality Engineer

Station for 12

ATES and inspection phases

7

DEFINE MEASUREMEASURE IMPROVEIMPROVE CONTROLCONTROLANALYZEANALYZE

of 29


Wee

k 44

Wee

k 42

Wee

k 40

Wee

k 38

Wee

k 35

Wee

k 32

Wee

k 30

Wee

k 28

Wee

k 26

Wee

k 24

Wee

k 22

Wee

k 20

Wee

k 18

0,13

0,12

0,11

0,10

0,09

0,08

0,07

0,06

Production Week

Pro

po

rtio

n

_P=0,09225

UCL=0,12329

LCL=0,06120

P Chart of Failed

6 months Weekly FAIL proportion P-Chart (May - October 2012)

Project Ring

!Proportion of FAILS is stable.

8

CTQ � FAIL% �# of Failed units through process

# of Outputs� 100 � 11,26% (FTY%=88,74%)

We use all historical data recorded in October 2012 as year 2012 representative and significant sample. During October 2012 we have add new

manual data collection form in order to collect defects since now not analyzed (test Operator self-repair; ATE inefficiencies; ATE operator

inefficiencies and errors; units tested more than one time) because not automatically reported by Testing Software (Abort Test form).

Outputs test data and results are recorded automatically by «SigmaQuest-Camstar» System software.

ABORT TEST units are collected manually by Quality Control team in a dedicated excel form.

FAIL repaired units data collection are recorded by repair team in «Data Collection» System Software.

DEFINE MEASUREMEASURE IMPROVEIMPROVE CONTROLCONTROLANALYZEANALYZE

of 29

Why use P-chart?

To see varible time trend when we have:

Discrete data by attributes (Proportion).

Varible subsroups.

To see data\process stability analysis


Data Collection reading (October-2012)

DEFINEDEFINE MEASURE IMPROVEIMPROVE CONTROLCONTROL

9

ANALYZEANALYZE

Project work will be developed for: «FAIL for manual

operation@ATE» and «FAIL for Low Efficiency on 3000W model»

«Defects already under analysis» will be not considered, their

analysis started before beginning of this project

of 29

Why use Pareto Diagram?

To understand the factors (defects)

incidence on total effects (FAIL rate).

Defect Phase Work FAILs FAIL %

FAIL for manual operation @ ATE 5,57

Defects already under analysis 2,32

Low Efficiency on 3000W model 1,04

FAIL for Supplier process 0,31

TK58H005A Coil damaged 0,25

IGBT-damaged 0,22

Inverted Coil Cables at MB 0,18

50 Pole flat cable 0,16

Inverted Coil Cables at BB 0,16

Board 02 PTH Assembly 0,16

DSP-damaged 0,16

Mechanical assembly board 02 0,09

# of Outputs FAILs FAIL %

11,26

FAILs 8 8 8 8 32327 149 61 21 15 10 9 9

Percent 1 1 1 1 549 22 9 3 2 2 1 1

Cum % 92 93 94 95 10049 72 81 84 86 88 89 90

Other

Mec

hanica

l assem

bly bo

ard 02

Inve

rted Co

il Ca

bles

at B

B

DSP-da

mag

ed

Boar

d 02

PTH

Assem

bly

Inve

rted Co

il Ca

bles

at M

B

50 Pole fla

t cab

le

IGBT

-dam

aged

TK58

H005

A Co

il da

mag

ed

FAIL fo

r Su

ppl ie

r proc

ess

Low Efficie

ncy on

300

0W m

odel

Defects alre

ady un

der a

nalys

is

FAIL fo

r man

ual o

pera

tion @ A

TE

700

600

500

400

300

200

100

0

100

80

60

40

20

0

FAIL

s

Pe

rce

nt

Pareto Chart of Defect Phase Work

49

!

8 8 8 8 32327 149 61 21 15 10 9 9

M

8 8 8 8 3 23 27 149 61 2 1 15 1 0 9 9

M


FAIL for Manual Operation @ ATE Analysis

DEFINEDEFINE MEASUREMEASURE ANALYZE IMPROVEIMPROVE CONTROLCONTROL

Quantitative Analysis

10

Qualitative Analysis

of 29

Failed Q.ty 103 84 60 30 21 15 14

Percent 31,5 25,7 18,3 9,2 6,4 4,6 4,3

Cum % 31,5 57,2 75,5 84,7 91,1 95,7 100,0

ABO

RT P

ush

Pro

tection mov

ed

S1 sw

itch no

t mov

ed

Miss

ing re

set

Wro

ng

VDR assy

Seria

lizza

tion Er

ror

Interm

itten

t Cab

ling

350

300

250

200

150

100

50

0

100

80

60

40

20

0

Fa

ile

d Q

.ty

Pe

rce

nt

Pareto Chart of Manual Operation @ ATE

8 8 8 8 32327 149 61 21 15 10 9 9

M


FAIL for Manual Operation @ ATE Root Causes 1\3

DEFINEDEFINE IMPROVEIMPROVE CONTROLCONTROL

1. Intermittent Cabling: The AC cable terminals could be deformed or damaged by use. If the operator doesn’t plug the cables correctly

or if he move the roll cable the connections could become intermittent. Also the narrow space makes it difficult to insert the cables.

2. VDR wrong assembly: This phase is performed at CAL test, in low light condition when the PVI is already assembled in Chassis. Also

VDR lead speacing doesn’t match with PCB Connector.

3. Serialization error: Because there are two PVIs in a trolley, the operator could wrongly read the Bar-code of the unit NOT under test.

4. S1 switch not moved: The S1 switching phases (3 times) are performed manually, in low light condition and by an inadequate tool.

Sometimes the operator switch partially the S1 causing a fail unit.

5. Protection moved: The Safety protection has two metal sensors that enable the beginning of the test when the sensors are in contact

with the metallic PVI chassis. Because of the protection is unstable, if the operator moves the protection the test will aborted.

6. Missing reset : The RESET TEST is a semi-manual test, the station is very close the ATE Final test. For this reason the operator can test

wrongly the PVI directly to FT instead of to RESET TEST.

7. ABORT button pushed: The safety «ABORT» push button is located in coincidence to trolley or PVI during the test. This could cause

the operator involuntary push of the button.

11

ANALYZEMEASUREMEASURE

ATE FT RESET

11 22 33 44

55 66 77

of 29


C1

C2

C4

C5

C3

C7

C8

C9

C10

C12

C13

Low Illumination at ATE

RESET test station too close at ATE

C11Wrong VDR assembly phase (PVI in chassis)

To many manual phases at ATE

Two PVI in a trolley

RESET test is complicated Manual test

ATEs equipment safety protection poor design

ATEs equipment AC WIRINGS not sufficiently robust

ATEs equipment AC WIRINGS difficult insertion

C6Improper tool to switch S1

ATEs equipment ABORT button inadequate position

VDR-CONNECTOR pin step mismatch

VDR bad packaging cause terminals bent

Intermittent Cabling

Serialization Error

Wrong VDR assembly

Missing reset

S1 switch not moved

Protection moved

ABORT Push


Causes Effects

! A cause can produce more than one effect

12

DEFINEDEFINE IMPROVEIMPROVE CONTROLCONTROLANALYZEMEASUREMEASURE

of 29

! An effect is produced by more than one cause

| | | | CONFIDENTIALCONFIDENTIALCONFIDENTIALCONFIDENTIAL13


C4

36%

C5

15%C8

11%

C9

11%

C1

5%

C3

4%

C2

4%

C13

3%

C11

3%

C12

3%

C10

2%

C6

2%C7

1%

«Weight» of each cause on the CTQ (FAIL%).

Causes C4; C5; C8, C9 and C1 will be addressed as priority!


of 29


96,396,095,795,495,194,8

Median

Mean

95,97595,97095,96595,96095,95595,950

1st Q uartile 95,851

Median 95,957

3rd Q uartile 96,096

Maximum 96,479

95,954 95,972

95,948 95,969

0,225 0,238

A -Squared 28,69

P-V alue < 0,005

Mean 95,963

StDev 0,231

V ariance 0,053

Skewness -1,18216

Kurtosis 5,25829

N 2623

Minimum 94,620

A nderson-Darling Normality Test

95% C onfidence Interv al for Mean

95% C onfidence Interv al for Median

95% C onfidence Interv al for StDev

95% Confidence Intervals

Summary for EFFICIENCY

FAIL for Low Efficiency % Analysis 1\4

The minimum efficiency spec value for 3.0KW inverter is 95%. We have FAILs due to efficiency% lower than spec value. To repair these units,

we must replace output coils and scrap the removed ones.

Here we want to verify the data distribution.

! Data are not Normal; P-Value < 0,05.

!Box Plot shows there are lots of outliers.

! Some units are out of minimum spec (95%).

This condition requires further investigation.

14


of 29

Why use Graphical Summary Tool?

Main Information:

Data (Efficiency%) distribution\normality

Position Indices

Dispersion Indices

Confidence Interval



Here we want to establish a FULL DOE (Design Of Experiment) to understand the more impacting factors on efficiency %, in order to get more

stable and within spec this value.

1. Statement of the Problem:

Basing on the results of the meetings and brainstorming performed in December 2012:

the most probable cause of Efficiency % variation is the saturation Inductance value of the Output Coils.

Since now we never studied the effects of the difference Inductance between the two inverter coils on the Efficiency. We want also

understand if a longer warm up time of the Inverter (rise of the internal inverter temperature) could change the efficiency.

2. Response Variable :

Efficiency %.

3. Factors and Levels:

FactorA: L1 Inductance – Level+: 540uH (SAT inductance@20A); Level-: 470uH (SAT inductance@20A).

FactorB: L2 Inductance – Level+: 540uH (SAT inductance@20A); Level-: 470uH (SAT inductance@20A).

Factor C: Inverter Warm-up Time – Level+: 10min; Level-: 1min

4. Choice of Design:

Full Factorial Design – 3 repetitions.

! 3 Factors; 2 levels = 23 Tests x 3 repetition = 24 Tests

15


of 29


5. Perform Experiment


The more impacting factor on the Efficiency % is the

interaction of A+B (Inductance L1 + inductance L2) .

6. Data Analysis part 1

16

B

A

BC

AC

ABC

C

AB

140120100806040200

Te

rm

Standardized Effect

2,1

A L1(SA T)

B L2(SA T)

C Warm-Up Time

Factor Name

Pareto Chart of the Standardized Effects(response is Efficiency, Alpha = 0,05)


of 29

Why use DOE Tool?

To understand the more impacting

factors (L1SAT,L2SAT, Warm-ip Time), on

Response Variable (Efficiency%)


540470

95,8

95,6

95,4

95,2

95,0

94,8

94,6

L2(SAT)

Me

an

470

540

L1(SAT)

Interaction Plot for EfficiencyData Means

FAIL for Low Efficiency % Root Causes 4\4

7. Data Analysis part 2If L1 and L2 inductances have different value we obtain a low Efficiency%. We have higher Efficiency% when L1 and L2 have the same value.

17


of 29

0,040,030,020,010,00-0,01-0,02-0,03-0,04

99

95

90

80

70

60

50

40

30

20

10

5

1

Residual

Perc

ent

Mean 2,960595E-15

StDev 0,01445

N 24

RJ 0,997

P-Value >0,100

Probability Plot of ResidualNormal

Why use Residual Normality Tool?

To understand if other unknown factors

occurred and influenced measurements,

then if the results are reliable. Residual is

the difference between 3repMean and

the relative measure.


FAIL for Manual Operation @ ATE Solutions 1\4

DEFINEDEFINE ANALYZEANALYZE IMPROVE CONTROLCONTROL

Add a portable Led light for each

operator at ATE

Modified transport: One PVI for Trolley

Installed VDR pins preforming machine

and packaging

New ATE interface PAD and SWS5

S1

S4

S8

Protected ABORT button

(keeping safety standards)S6

RESET automated in new ATE HW\SW S2

C1

C2

C4

C5

C3

C7

C8

C9

C10

C12

C13

Low Illumination at ATE

RESET test station too close at ATE

C11Wrong VDR assembly phase (PVI in chassis)

Operator Oversight. To many manual phases at ATE

Two PVI in a trolley

RESET test is complicated Manual test

ATEs equipment safety protection poor design

ATEs equipment AC WIRINGS not sufficiently robust

ATEs equipment AC WIRINGS difficult insertion

C6Improper tool to switch S1

ATEs equipment ABORT button inadequate position

VDR-CONNECTOR pin step mismatch

VDR bad packaging cause terminals bent

Modified Work-phases flow layoutS3

MOVED VDR1 and VDR3 at ICTS7

18

MEASUREMEASURE

of 29


FAIL for Manual Operation @ ATE Solutions 2/4

DEFINEDEFINE IMPROVE CONTROLCONTROL

BI

BURN-IN

OPOPOP

Burn-In

Deposit

OP

OP

Take

label

LABEL

Label Assembly

CAL

PRE-TEST

ONE OPERATOR

DRIVE TWO ATE

Take

2 VDRs

2 VDR Assembly

VDR

OP

INSP

AC Cable

connection

DC PAD

connectionAC Cable

screwing

OP

FT

RST

FINAL TEST

OPOP

ASSEMBLY LINE

CAL OPERATOR

PHASE

INSP

OP

DC PAD

connectionAC PAD

screwing

OP

Protection

install

Protection

install

OP

DC PAD

connection

AC PAD

screwingFT OPERATOR

PHASE

S3 Test Line process mapping – ASME logic diagram (After)Modified Work-phases flow layout

19

ANALYZEMEASUREMEASURE ANALYZEANALYZE

of 29

SAFETY -TESTSAFETY -TEST

RE

SE

T-T

ES

TR

ES

ET

-TE

ST



DEFINEDEFINE IMPROVE CONTROLCONTROL

Work phases Before\After Comparison

Takt time = Daily available time = 14h = 50400sec = 102.8“

Customer Demand 490 490

Cycle Time(Before) = 1110sec

N° operators(Before) = Cycle Time(Before) = 1110sec = 10,8

Takt time 102,8sec

Symbol Meaning Work Process before Corrective action Work process after corrective action "Saving"

Transformation Operation 3 2 1

Inspection\Test 7 5 2

Transport\Movement 34 24 10

Waiting 8 5 3

Deposit\Storage 1 1 0

Transformation Operation Support 24 11 13

N° operators(After) = Cycle Time(After) = 810sec = 7,8

Takt time 102,8sec

Cycle Time(After) = 810sec

S3

20

ANALYZEANALYZEMEASUREMEASURE

SortingSorting SettingSetting ShineShine StandardizingStandardizing SustainSustain

Eliminated

useless tools and

documents.

Made process

more ergonomic

(tools\document)

Add procedure to

keep place clean

and well organized

Standardized

Tools and

Work-stations

Keep control

maintaining and

reviewing standards

Three temporary operators less

of 29



Here we want to evaluate the possible risk we could have using the new ATE Interface PAD, understanding witch kind of failure it could

cause and provide a preventive corrective action. So we use a FMEA (Failure Mode Effect Analysis).

Occu

rren

ce

De

tectio

n

Seve

rity

RP

M

Occu

rren

ce

De

tectio

n

Seve

rity

RP

M

Breaking of the

connectorFAIL RESET test

Interface bumps with connectors if not

centered during his installation 7 2 8 112

Add plastic guide to keep Interface in

the right position during his

installation

3 2 8 48

Plastic Slip offRadio Board cannot be

installedPCB connector not perfectly straight 6 4 8 192

Modified Soldering tray to keep

straight connector.2 4 8 64

Termination

Switch

Break of the cursor

(not identifiable)

Missing termination

line on the field

AB interface bumps with TS if not well

lifted up5 7 6 210

Modified AB interface lift system

adding a magnet to keep it lifted.2 6 7 84

IND\PAR Switch Break of the cursor Fail Cal or Ft testAB interface bumps with I\P swotch if not

well lifted up3 2 8 48

Automatic bar code reader out of

position for wrong pressure calibration2 2 8 32

Wrong barcode label Position 3 2 8 48

AUX BUS

connector

Serialization

FMEA parameter Final Parameter

Component Fail Mode Effect Cause Modification

Wrong seril number

recorded in memoryTest FAIL

FAIL for Low Efficiency % Solutions

As per result of DOE the root cause is the

unbalancing SAT Inductances (20A)

between the two Inverter coils.

In order to improve and keep stable > 95%

the Efficiency we will use coils paired with

balanced Inductance Value (6 pairings).

S9C14

21

DEFINEDEFINE IMPROVE CONTROLCONTROLANALYZEANALYZEMEASUREMEASURE

of 29


S1 S3

S2

Solutions Implementation Stages

Solution Implementation Stage1

Start date 07-Jan-2013 Solution Implementation Stage2

Start date 11-Feb-2013

S9S9

S7S7S8S8

Solution # Stage2 Solutions short description

S07 MOVED VDR1 and VDR3 at ICT

S08 Installed VDR pins preforming machine and packaging

S09 Coils paired with balanced Inductance Value (6 pairing).

Solution

#Stage1 Solutions short description

S01 Add a portable Led light for each operator at ATE

S02 RESET automated in new ATE HW\SW

S03 Modified Work-phases flow layout

S04 Modified transport: One PVI for Trolley

S05 New ATE interface PAD and SW

S06 Protected ABORT button

22

S4 S5

S6

DEFINEDEFINE IMPROVE CONTROLCONTROLANALYZEANALYZEMEASUREMEASURE

of 29


Control Systems

DEFINEDEFINE IMPROVEIMPROVE CONTROL

Visual alarms at ATE

New Work-phases flow layout

New Specification

And Procedure

ANALYZEANALYZEMEASUREMEASURE ANALYZEANALYZE

New ATE fixture

of 29


Project Work control

DEFINEDEFINE IMPROVE CONTROLANALYZEMEASUREMEASURE ANALYZEANALYZE IMPROVEIMPROVE

BEFORE – (4 Weeks October 2012) AFTER – (4 Weeks Feb\Mar 2013)

#$%&%'()*+,-+./01)+23(,@$56 � 7, 78%

#$%&%'()&(96'':;;;<*(=1. � >, ;?%

#$%&%'()*+,-+./01)+23(,@$56 � >, @A%

#$%&%'()&(96'':;;;<*(=1. � ;%

-77,4%

Cleared

FTY=88,74% FTY=94,47%

24

Re

sult

sR

esu

lts

of 29

Defects already

under analysis

5(2+.#$%&% � >>, @A% #$%&% � 7, 7:%-51%

B=-4,31%B=-4,31%

B=-1,04%B=-1,04%

Week 15Week 10Week 05Week 50Week 45Week 40Week 34Week 28Week 23Week 18

0,150

0,125

0,100

0,075

0,050

Production Week

Pro

po

rtio

n

_P=0,0555

UCL=0,0778

LCL=0,0332

Before Project Work Start Stage 1 Start Stage 2

1

1

1

1

1

1P Chart of Failed by Time


FAIL for Manual Operation @ ATE control

25

Missing RESET

S1 Switch not moved

Protection Moved

ABORT Push

Cleared

Intermittent Cabling 80,6% reduced

Wrong VDR Assembly 72,5% reduced

RS485 not inserted

AUX-BUS not inserted

USB not inserted

New Issues

05/03/201327/02/201321/02/201316/02/201312/02/201429/10/201223/10/201217/10/201211/10/201205/10/201201/10/2012

0,10

0,08

0,06

0,04

0,02

0,00

MFG Data

Pro

po

rtio

n

_P=0,0126

UCL=0,0280

LCL=0

Before After

P Chart of FAIL for Manual operations@ATE by Time

Re

sult

sR

esu

lts


of 29

Failed Q.ty 103 84 60 30 21 15 14

Percent 31,5 25,7 18,3 9,2 6,4 4,6 4,3

Cum % 31,5 57,2 75,5 84,7 91,1 95,7 100,0

ABOR

T Pu

sh

Protec

tion mov

ed

S1 switc

h no

t mov

ed

Miss

ing re

set

Wrong

VDR

assy

Seria

lizza

tion Erro

r

Interm

itten

t Cab

ling

350

300

250

200

150

100

50

0

100

80

60

40

20

0

Faile

d Q

.ty

Perc

en

t

Pareto Chart of FAIL for Manual Operation @ ATE Oct-12

Failed Q.ty 33 27 26 19 16

Percent 27,3 22,3 21,5 15,7 13,2

Cum % 27,3 49,6 71,1 86,8 100,0

USB Ca

ble no

t ins

erted

AUX-

BUS

conn

ector n

ot in

serted

RS48

5 Co

nnec

tor NO

T Inse

rted

Wrong

VDR

Ass

embly

Interm

itten

t Cab

ling

120

100

80

60

40

20

0

100

80

60

40

20

0

Faile

d Q

.ty

Pe

rce

nt

Pareto Chart of Manual Operation @ ATE - AFTER

8 8 8 8 32327 149 61 21 15 10 9 9

M

8 8 8 8 32327 149 61 21 15 10 9 9

M8 8 8 8 32327 149 61 21 15 10 9 9

M

8 8 8 8 32327 149 61 21 15 10 9 9

M


S=0,1 (StD estimated)

d=0,018 (accuracy established)C �

2

D

2= 123 units

FAIL for Low Efficiency % control 1/2

26

Sample size (min) calculation to estimate the Efficiency% MEAN

96,5

96,0

95,5

Mea

n

51464136312621161161

1,0

0,5

0,0

Ran

ge

51464136312621161161

Xbar-R ChartsConfirm that the Before and After process conditions are stable.

Normality Plots

The points should be close to the line.

Normality Test

(Anderson-Darling)

Results Fail Pass

P-value < 0,005 0,080

Before After

Before/After Capability Comparison for Efficiency A vs Efficency Af

Diagnostic Report

Before After

Before After

100%

> 0,50,10,050

NoYes

P = 0,029

> 0,50,10,050

NoYes

P = 0,189

Before

LSL USL

After

Actual (overall) capability is what the customer experiences.

-- The process mean did not change significantly (p > 0.05).

-- The process standard deviation was reduced significantly (p < 0.05).

Conclusions

Before: Efficiency A After: Efficency Af

95 * 97

Lower Spec Target Upper Spec

Customer Requirements

Mean 95,951 95,985 0,033926

Standard deviation 0,26381 0,19539 -0,068420

Capability

Pp 1,26 1,71 0,44

Ppk 1,20 1,68 0,48

Z.Bench 3,55 4,97 1,42

% Out of spec 0,02 0,00 -0,02

PPM (DPMO) 191 0 -191

Statistics Before After Change

Reduction in % Out of Spec

to 0,00%.

% Out of spec was reduced by 100% from 0,02%

Before/After Capability Comparison for Efficiency A vs Efficency Af

Summary Report

Was the process standard deviation reduced?

Did the process mean change?

Actual (overall) Capability

Are the data inside the limits?

Comments


of 29

Why use Xbar-R Chart?

To see varible time trend when we have:

Continuos data.

Sample subgroups size<10 and>1.

To see data\process stability.

Why use Before\After tool?

To compare data before - after improve:

Normality, StDV, Mean, Capability,

DPPM, final response of improvement

= 112 units112 units112 units112 unitsCK

=C

1 LC

�

Efficiency% manual measurements using LAB instruments during

production. Because the large production per day , it is not possible

measure 100% of the produced units. Basing on production

time\quantity, we can perform a systematic subgroups sampling: 3

untis each 30 produced (38 sampling) repeated for units «before» and

units «after» Solution.


FAIL for Low Efficiency % control 2/2

Specification for Efficiency% MEAN is 96%. Here we want to understand if, after improvement, Efficiency% MEAN of population (EFF%PMEAN)

will be statistically equal to Spec value 96% (EFF%SMEAN). We use the 1-Sample-t test (Hypothesis Testing).

96,3096,1596,0095,8595,70

20

15

10

5

0X_

Ho

Efficency After

Fre

qu

en

cy

Histogram of Efficency After(with Ho and 95% t-confidence interval for the mean)

Hypotesis:

H0: EFF%PMEAN = EFF%SMEAN

HA: EFF%PMEAN ≠ EFF%SMEAN

Results:

P-Value >0,05 (HA refusal).

Population MEAN is statistically not different from Spec Value

(with 95% of confidence)

The Confidence Interval of the sample MEAN contains H0 that

means the Population MEAN is not different than MEAN Spec

Value (with 95% of confidence)

27


of 29

Why use Hypotesis Test 1 sample T-test?

To compare MEAN of the statistic sample

with Reference MEAN; see if there are

statistically equal or not (with 95% of

confidence).


Scrap coils: 9.000€

3 temporary employees operators at ATE: 120.000€

Savings of the Project Work

DEFINE MEASURE IMPROVE CONTROL

Considering a 2013 stable production rate we can

estimate the following SAVINGS:

Charges for ATEs new release: 51.000€

+

+-=Total Saving: 86.000€ (first year)

Overtime work: 8.000€

Removed one ATE and used in another AREA.

+

Lesson learned

Six Sigma and Lean tools

DMAIC approach as problem solving

Team Work

Sampling efficacy

HARD SAVINGS

ANALYZEMEASURE ANALYZE IMPROVE

Next Steps

Improvement of VDR assembly

Know How exporting in other areas

New Project work development

Improvement of Intermittent cabling

Start new Lean &Sigma Projects

The reduction by half of the FAIL% allowing saving:

SOFT SAVINGS Operator at repair station can be dedicated also to other jobs.

Sustaining Engineer can be dedicated to other Project Work.

of 29


End of Project Work

DEFINE CONTROLMEASURE ANALYZE IMPROVE

End

of

project

work

End

of

project

work

DD

MM

AAI

C

Quality Department

Power-One Italy S.p.A.

Andrea Grilli

of 29

Date post:	20-Jan-2015
Category:	Technology
Upload:	gmsl
View:	86 times
Download:	6 times

2 power one

Technology