Analysis of Assembly Line Balancing in Garment Production by Simulation

Association
of
Universities for Textiles

E-TEAM
European Masters in Advanced Textile Engineering

"Analysis of Assembly Line Balancing in
Garment Production by Simulation”
In the context of Lean Manufacturing and the TPS

Lina Katharina Rambausek

Promoter:
Prof. Dr. Fatma Kalaoğlu,
Technical University Istanbul, Istanbul, Turkey
Prof. Dr. Mario Araújo,
University of Minho, De Minho, Portugal
Academic year: 2007-2008


www.congnhemay.net

i

Abstract
Subject of this dissertation is the analysis of assembly line balancing in garment
production by simulation. Aspects of Lean Manufacturing (LM) and the Toyota
Production System (TPS) will be discussed in reference to the simulation experiments. The analysis is accomplished with help of a simulation program, “Enterprise Dynamics”. The thesis is developed in connection to the master study program “European Masters in Advanced Textile Engineering” which is organised by
the “Association of Universities for Textiles” (AUTEX).
The results are based on primary research and knowledge that was gained mainly

during the stay at the Technical University Istanbul, Turkey, as well as on field trips
to companies in the sector of garment production. The dissertation highlights
weaknesses and constraints in the application of simulation programs concerning
garment production. It further explores the opportunities a simulation program
could offer European manufacturers in order to stay competitive.
Also in the textile sector, best practices as they are applied at other producing
companies should be considered, and seen as benchmark. According to Jeffrey K.
Liker (2004)1 the Japanese car manufacturer Toyota had it’s origin in the textile
sector, the weaving industry. It stands to reason that the ideas of the car manufacturing system today could be applied by the way of knowledge transfer to fields of
textile production. This thesis will focus on the idea of LM (Lean Manufacturing) as
well as on the strongly connected TPS (Toyota Production System).
The outcomes of this dissertation is intended to give applicants of simulation programs in the textile field an overview about the options to improve their business
with simulation. It will focus on opportunities and constraints of using a simulation
program within the application of production line balancing.

Keywords: Line Balancing, Garment Manufacturing, Simulation Software, Enterprise Dynamics, Lean Manufacturing, Toyota Production System


www.congnhemay.net

ii

Table of Content
ABSTRACT .............................................................................................................I
TABLE OF CONTENT............................................................................................II
LIST OF ILLUSTRATIONS................................................................................... VI
LIST OF TABLES ............................................................................................... VIII
LIST OF EQUATIONS ........................................................................................... X
LIST OF ABBREVIATIONS.................................................................................. XI
PREFACE ............................................................................................................ XII

DECLARATION .................................................................................................. XIII
SUMMARY.......................................................................................................... XIV
1

INTRODUCTION .............................................................................................1

2

OBJECTIVES ..................................................................................................6

3

APPROACH ....................................................................................................7

4

THE MANUFACTURING CONCEPTS ............................................................9

4.1
Progressive Bundle System (PBS).................................................................................... 9
4.1.1 Concept........................................................................................................................ 9
4.1.2 Advantages of PBS...................................................................................................... 9
4.1.3 Disadvantages of PBS ................................................................................................. 9
4.2
Modular Manufacturing (MM) ........................................................................................... 10
4.2.1 Concept...................................................................................................................... 10
4.2.2 Advantages of MM ..................................................................................................... 11
4.2.3 Disadvantages of MM ................................................................................................ 12
,
4.3

Lean Manufacturing (LM) ................................................................................................. 12
4.3.1 Concept...................................................................................................................... 13
4.3.1.1
Pull system ........................................................................................................ 13
4.3.1.2
One-piece flow .................................................................................................. 14
4.3.1.3
Value-added ratio .............................................................................................. 14
4.3.1.4
Handling reduction ............................................................................................ 16
4.3.1.5
Single minute exchange of die (SMED) ............................................................ 16


iii

www.congnhemay.net

4.3.1.6
Standard work ................................................................................................... 16
4.3.1.7
Takt time............................................................................................................ 16
4.3.1.8
Line balancing ................................................................................................... 16
4.3.1.9
Productivity........................................................................................................ 17
4.3.1.10
Flow velocity ................................................................................................. 17
4.3.2 Advantages of LM: ..................................................................................................... 17
4.3.3 Disadvantages of LM ................................................................................................. 18

,
4.3.4 Toyota Production System ........................................................................................ 18
4.4
Mixed Manufacturing Module Design - Hybrid Version................................................. 21

5

ISTCOMP.......................................................................................................22

5.1
Data base ........................................................................................................................... 22
5.2
Product ............................................................................................................................... 22
5.3
Layout................................................................................................................................. 23
5.3.1 Section I & II. in detail ................................................................................................ 29
5.3.2 I. Body - Subassembly ............................................................................................... 30
5.3.3 II. Collar and Lining Subassembly ............................................................................. 34
5.3.4 Section III.& IV in detail.............................................................................................. 38
5.3.5 III. Sleeve Subassembly ............................................................................................ 39
5.3.6 IV Final Assembly ...................................................................................................... 41
5.3.7 Workforce................................................................................................................... 45
5.4
The work flow .................................................................................................................... 49
5.5
Time Studies ...................................................................................................................... 55

6

LINE BALANCING ........................................................................................59

,

6.1
Line Balancing in general ................................................................................................ 59
6.2
Line balancing at HUGO BOSS........................................................................................ 66
6.2.1 Introduction ................................................................................................................ 66
6.2.2 Production site ........................................................................................................... 66
6.2.3 Workforce................................................................................................................... 67
6.2.4 General system of planning: ...................................................................................... 67
6.2.5 Efficiency.................................................................................................................... 69
6.2.6 Special conditions in Dynamic lines........................................................................... 73
6.3
Simulation .......................................................................................................................... 74
6.4
Line Balancing in garment production ........................................................................... 75

7

SOFTWARE ENTERPRISE DYNAMICS, ......................................................77
,,,

7.1
Application ....................................................................................................................... 77
7.1.1 Model ......................................................................................................................... 77
7.1.2 Simulate ..................................................................................................................... 78
7.1.3 Visualize..................................................................................................................... 78
7.1.4 Control ....................................................................................................................... 78
7.2
User .................................................................................................................................... 79

7.3
Data..................................................................................................................................... 82

8
8.1
8.2
8.3

9

SIMULATION MODEL...................................................................................83
Simplifications................................................................................................................... 83
Aspects of Lean Manufacturing....................................................................................... 84
Setup process.................................................................................................................... 85

EXPERIMENTS .............................................................................................93

9.1
Experiment A0 ................................................................................................................... 97
9.1.1 Results of experiment A0........................................................................................... 97
9.2
Experiment A1 ................................................................................................................... 99
9.2.1 Improvement strategy - Experiment A1 ..................................................................... 99


www.congnhemay.net

iv

9.2.2 A1 Changes ............................................................................................................. 101

9.2.3 Results of experiment A1......................................................................................... 103
9.3
Experiment A2 ................................................................................................................. 103
9.3.1 Improvement strategy - Experiment A2 ................................................................... 103
9.3.2 A2 Changes ............................................................................................................. 103
9.3.3 Results of Experiment A2: ....................................................................................... 106
9.4
Experiment A3 ................................................................................................................. 106
9.4.1 Improvement strategy - Experiment A3 ................................................................... 106
9.4.2 A3 Changes ............................................................................................................. 106
9.4.3 Results of experiment A3......................................................................................... 107
9.5
Experiment A4 ................................................................................................................. 107
9.5.1 Improvement strategy - Experiment A4 ................................................................... 108
9.5.2 A4 Changes ............................................................................................................. 108
9.5.3 Results of experiment A4......................................................................................... 108
9.6
Overview experiment A .................................................................................................. 109
9.6.1 Output ...................................................................................................................... 110
9.6.2 Takt time .................................................................................................................. 111
9.6.3 Number of operators ................................................................................................ 112
9.6.4 Productivity per operator.......................................................................................... 113
9.6.5 Average content in subassembly queues ................................................................ 114
9.6.6 Average stay time of the product in the queue ........................................................ 116
9.6.7 WIP values ............................................................................................................... 119
9.6.8 Throughput time....................................................................................................... 120
9.7
Experiment B ................................................................................................................... 121
9.8
Experiment B1 ................................................................................................................. 121

9.8.1 Improvement strategy - Experiment B1 ................................................................... 121
9.8.2 B1 Changes ............................................................................................................. 121
9.8.3 Results of experiment B1......................................................................................... 124
9.9
Experiment B2 ................................................................................................................. 124
9.9.1 Improvement strategy - Experiment B2 ................................................................... 125
9.9.2 B2 Changes ............................................................................................................. 125
9.9.3 Results of experiment B2......................................................................................... 126
9.10
Overview experiment B .................................................................................................. 127
9.10.1 Output ...................................................................................................................... 127
9.10.2 Number of Operators ............................................................................................... 128
9.10.3 Productivity per operator.......................................................................................... 130

10

CONCLUSION .........................................................................................133

10.1
10.2
10.3
10.4
10.5
10.6

Strengths.......................................................................................................................... 133
Weaknesses..................................................................................................................... 134
Opportunities................................................................................................................... 135
Threats ............................................................................................................................. 135
Personal problems of the author................................................................................... 136

Future outlook ................................................................................................................. 137

A.

APPENDIX A ...........................................................................................139

A.1 List of minimum wages by country ..................................................................................... 139

B.

APPENDIX B ...........................................................................................141

B.1 Data Basis – Machinery ........................................................................................................ 141

C.

APPENDIX C ...........................................................................................147

C1.

ED System requirements: .............................................................................................. 147

D.

APPENDIX D ...........................................................................................148


www.congnhemay.net

D1.

E.

v

Simulation Model Layout................................................................................................ 148

APPENDIX E ...............................................................................................149

Overview experiment A ............................................................................................................... 149
E1.
Output of the sections individually ............................................................................... 149
E2.
Number of operators per section .................................................................................. 150
E3.
Number of operators per section .................................................................................. 152

F.

APPENDIX F ...............................................................................................154

Overview experiment B ............................................................................................................... 154
F1.
List of operators and their assignments to servers according to Layout of ISTCOMP
154

BIBLIOGRAPHICAL REFERENCES .................................................................156


www.congnhemay.net

List of Illustrations
Fig. 3-1 Procedural method........................................................................................................... 8
Fig. 4-1 Value added vs. Non-value-added activities.................................................................. 15
Fig. 4-2 Potential effect on Lead time after reducing non-value-added activities by 50% .......... 15
Fig. 4-3 Decision tree for evaluation of processes...................................................................... 20
Fig. 5-1 Ladies’ jacket basic model ............................................................................................. 23
Fig. 5-2 Drawing of ladies’ jacket production line (sections I & II) .............................................. 24
Fig. 5-3 Advanced sketch of the production line (all sections).................................................... 24
Fig. 5-4 Layout ladies’ jacket production line, work flow at 22.02.2008...................................... 27
Fig. 5-5 Layout ladies’ jacket production line, work flow at 22.02.2008 (part1/2) ....................... 29
Fig. 5-6 Area which is worked-on in section I. Body ................................................................... 30
Fig. 5-7 Parts which are worked on in section II.C&L ................................................................. 34
Fig. 5-8 Layout Ladies’ jacket production line, work flow at 22.02.2008 (part2/2) ...................... 38
Fig. 5-9 Parts which are sub-assembled in section III ................................................................ 39
Fig. 5-10 Parts which are assembled in section IV: .................................................................... 41
Fig. 5-11 Number of workers I .................................................................................................... 46
Fig. 5-12 Number. of workers II .................................................................................................. 46
Fig. 5-13 Average age of the workers ......................................................................................... 47
Fig. 5-14 Average experience in this job..................................................................................... 47
Fig. 5-15 Number of operations the operators are trained-in...................................................... 48
Fig. 5-16 Work flow chart Ladies’ jacket production line, work flow at 22.02.2008 .................... 50
Fig. 5-17 Work flow chart Ladies’ jacket production line, work flow at 22.02.2008 (part1/4) ..... 51
Fig. 5-18 Work flow chart Ladies’ jacket production line, work flow at 22.02.2008 (part2/4) ..... 52
Fig. 5-19 Work flow chart Ladies’ jacket production line, work flow at 22.02.2008 (part3/4) ..... 53
Fig. 5-20 Work flow chart Ladies’ jacket production line, work flow at 22.02.2008 (part4/4) ..... 54
Fig. 5-21 REFA standard form for time studies........................................................................... 56
Fig. 5-22 REFA standard form for time studies additional side................................................... 57
Fig. 6-1 Work element sharing .................................................................................................... 63
Fig. 6-2 Division of work element ................................................................................................ 64

Fig. 6-3 Assembly sequence....................................................................................................... 65
Fig. 6-4 Hierarchies at HB ........................................................................................................... 67
Fig. 7-1 Logo of the simulation software Enterprise Dynamics................................................... 77
Fig. 7-2 VR-simulation of a warehouse system & a production line with the ED Logistic Suite . 80
Fig. 8-1 The layout of the simulation model ................................................................................ 85
Fig. 8-2 The atoms source, queue, server and assembler ......................................................... 86
Fig. 8-3 Simulation model after the channels are connected...................................................... 86
Fig. 8-4 Simulation model after the channels are connected (more detailed) ............................ 87
Fig. 8-5 Application of the values of operation 7 in “Stat:Fit” ...................................................... 88
Fig. 8-6 Changing the atoms properties...................................................................................... 90
Fig. 8-7 After a test run of 90 hours the output volume is 7582 units. ........................................ 91
Fig. 8-8 3D Model View after inserting the atom “VR building” ................................................... 92
Fig. 9-1 Experimentation Wizard................................................................................................. 95
Fig. 9-2 Experimentation Wizard, Performance Measures PFM ................................................ 96
Fig. 9-3 Library Tree ED............................................................................................................ 100
Fig. 9-4 Status Monitor .............................................................................................................. 100
Fig. 9-5 Monitor ......................................................................................................................... 101
Fig. 9-6 Output per shift of entire production line...................................................................... 110
Fig. 9-7 Takt time of the entire production line.......................................................................... 111
Fig. 9-8 Total number of operators of the production line ......................................................... 112
Fig. 9-9 Productivity per operator [units/operator]..................................................................... 113
Fig. 9-10 Average content in the section’s queues ................................................................... 115
Fig. 9-11 Average content in the section queue IIIb. Sleeve Prep............................................ 116
Fig. 9-12 Average stay time in the section’s queues ................................................................ 118
Fig. 9-13 Average stay time in the section IIIb. Sleeve Preparation Queue ............................. 118
Fig. 9-14 WIP values of the entire production line according to values of A0 to A4 ................. 119
Fig. 9-15 Throughput time of the entire production line according to values of A0 to A4 ......... 120

vi

www.congnhemay.net

Fig. 9-16 Total output of the entire production line ................................................................... 127
Fig. 9-17 Number of operators entire production line ............................................................... 128
Fig. 9-18 Number of operators per section ............................................................................... 130
Fig. 9-19 Prodctivity per worker ................................................................................................ 131
Fig. 9-20 Overview B - Productivity of operators per section.................................................... 132
Fig. B-1 Machinery at ISTCOMP within the sections I. Body and II. C&L................................. 145
Fig. B-2 Machinery at ISTCOMP within the sections III. Sleeve and IV. Assembly.................. 146
Fig. D-1 “Enterprise Dynamics” simulation model layout .......................................................... 148
Fig. D-2“Enterprise Dynamics” simulation model layout with connections ............................... 148

vii


www.congnhemay.net

List of Tables
Table 4-1 Areas in which waste can be avoided......................................................................... 19
Table 5-1 Example: Code in section II. Collar & Lining............................................................... 25
Table 5-2 Example: Code in section II. Collar & Lining............................................................... 26
Table 5-3 Number of operations per section............................................................................... 28
Table 5-4 Operations of section I. Body - Subassembly (part 1/4) ............................................. 30
Table 5-5 Operations of section I. Body - Subassembly (part 2/4) ............................................. 31
Table 5-6 Operations of section I. Body - Subassembly (part 3/4) ............................................. 32
Table 5-7 Operations of section I. Body - Subassembly (part 4/4) ............................................. 33
Table 5-8 Operations of section II. Collar and Lining - Subassembly (part 1/4) ......................... 34
Table 5-9 Operations of section II. Collar and Lining - Subassembly (part 2/4) ......................... 35
Table 5-10 Operations of section II. Collar and Lining - Subassembly (part 3/4) ....................... 36

Table 5-11 Operations of section II. Collar and Lining - Subassembly (part 4/4) ....................... 37
Table 5-12 Operations section III. Sleeve Subassembly (part 1/2.............................................. 39
Table 5-13 Operations section III. Sleeve Subassembly (part 2/2) ............................................ 40
Table 5-14 Operations of section IV Final Assembly (part 1/4) .................................................. 41
Table 5-15 Operations of section IV Final Assembly (part 2/4) .................................................. 42
Table 5-16 Operations of section IV Final Assembly (part 3/4) .................................................. 43
Table 5-17 Operations of section IV Final Assembly (part 4/4) .................................................. 44
Table 5-18 Number of workers per section ................................................................................. 45
Table 5-19 Standard symbols determined by The American Society of Mechanical Engineers 49
Table 6-1 Example calculation 1 ................................................................................................. 60
Table 6-2 Example calculation 2 ................................................................................................. 62
Table 6-3 Example calculation 3 ................................................................................................. 62
Table 6-4 Example: Operator A fulfils 4 different operations ...................................................... 71
Table 6-5 Line balancing sheet at HB ......................................................................................... 72
Table 7-1 Overview Application fields and clients....................................................................... 79
Table 8-1 Operations and their distributions (part 1/3) ............................................................... 88
Table 8-2 Operations and their distributions (part 2/3) .............................................................. 89
Table 8-3 Operations and their distributions (part 3/3) .............................................................. 90
Table 9-1 Output values experiment A0...................................................................................... 98
Table 9-2 Input values experiment A0 ........................................................................................ 98
Table 9-3 A1 - 1st Change - results gained through simulation................................................ 101
Table 9-4 A1 2nd Change - results gained through simulation................................................. 102
Table 9-5 Effect of the changes in experiment A1 .................................................................... 102
st
Table 9-6 A2 1 Change - results gained through simulation................................................... 104
nd
Table 9-7 A2 2 Change - results gained through simulation .................................................. 104
rd
Table 9-8 A2 3 Change - results gained through simulation................................................... 105
th

Table 9-9 A2 4 Change - results gained through simulation................................................... 105
Table 9-10 Effect of the changes in experiment A2 .................................................................. 105
Table 9-11 A3 Changes- results gained through simulation ..................................................... 107
Table 9-12 A4 changes – Reduction in queue size .................................................................. 108
Table 9-13 A4 Change in WIP value......................................................................................... 109
Table 9-14 A4 Change in Throughput time............................................................................... 109
Table 9-15 Overview experiment A – Output volume of the entire manufacturing line (1/2) .... 110
Table 9-16 Overview experiment A – Output volume of the entire manufacturing line (2/2) .... 110
Table 9-17 Overview experiment A – Takt time of the entire production line ........................... 111
Table 9-18 Overview experiment A – Number of operators of the entire production line......... 112
Table 9-19 Overview experiment A – Productivity of operators (output/no. of operator).......... 113
Table 9-20 Overview experiment A – Average content in queue of section I. Body................. 114
Table 9-21 Overview experiment A – Average content in queue of section II. Collar & Lining 114
Table 9-22 Overview experiment A – Average content in queue of section III. Sleeve............ 114
Table 9-23 Overview experiment A – Average content in queue of section IIIb. Sleeve Prep. 115
Table 9-24 Overview experiment A – Average stay time in queue of section I Body ............... 116
Table 9-25 Overview experiment A – Average stay time in queue of section II Collar & Lining116
Table 9-26 Overview experiment A – Average stay time in queue of section III Sleeve .......... 117

viii


www.congnhemay.net

Table 9-27 Overview experiment A – Average stay time in queue of section IIIb. Sleeve Prep.117
Table 9-28 Overview experiment A – WIP values .................................................................... 119
Table 9-29 Overview experiment A – Throughput time of the production line.......................... 120
Table 9-30 Number of operators entire line .............................................................................. 124
Table 9-31 Output entire line..................................................................................................... 124
Table 9-32 Number of operators of the entire production line. ................................................. 126

Table 9-33 Output volume of the total production line .............................................................. 126
Table 9-34 Overview B - Output of the entire production line ................................................... 127
Table 9-35 overview B – Total number of Operators ................................................................ 128
Table 9-36 overview B – Total number of Operators comparison A0 to B2 ............................. 128
Table 9-37 Overview B - Operator number within section I. Body............................................ 129
Table 9-38 Overview B - Operator number within section IV. Assembly .................................. 129
Table 9-39 Overview B – Productivity per operator entire production line................................ 130
Table 9-40 Overview B – Productivity per operator entire production line, A0 vs. B2 .............. 130
Table 9-41 Overview B - Productivity of operators in section I. Body....................................... 131
Table 9-42 Overview B - Productivity of operators in section II. C&L ....................................... 131
Table 9-43 Overview B - Productivity of operators in section III. Sleeve .................................. 132
Table 9-44 Overview B - Productivity of operators in section IV. Assembly ............................. 132
Table A-1 Monthly gross minimum wage rates of an full-time adult employees. aged 23+ [1] 139
Table B-1 Machinery at ISTCOMP............................................................................................ 141
Table C-1 Hardware configurations .......................................................................................... 147
Table E-1 Overview experiment A – Output volume per shift section I. Body .......................... 149
Table E-2 Overview experiment A – Output volume per shift section II. Collar & Lining.......... 149
Table E-3 Overview experiment A – Output volume Section III. Sleeve................................... 149
Table E-4 Overview experiment A – Output volume section IIIb. Sleeve Preparation ............. 150
Table E-5 Overview experiment A – Number of operators in section I. Body and II. C&L ....... 150
Table E-6 Overview experiment A – Number of operators in section II. C&L........................... 150
Table E-7 Overview experiment A – Number of operators in section III. Sleeve...................... 151
Table E-8 Overview experiment A – Number of operators in section IIIb. Sleeve Prep. .......... 151
Table E-9 Overview experiment A – number of operators in section IV. Assembly ................. 151
Table E-10 Overview experiment A – Productivity of operators per output value in section I. . 152
Table E-11 Overview experiment A – Productivity of operators per output value in section II. 152
Table E-12 Overview experiment A – Productivity of operators per output value in section III.152
Table E-13 Overview experiment A – Productivity of operators per output value in section IIIb.153
Table E-14 Overview experiment A – Productivity of operators per output value in section IV.153
Table F-1 Assignment of operators to operations at ISTCOMP (part 1/2)................................ 154

Table F-2 Assignment of operators to operations at ISTCOMP (part 22)................................. 155

ix


www.congnhemay.net

List of Equations
Equation 1-1 Productivity .............................................................................................................. 3
Equation 1-2 Labour productivity .................................................................................................. 3
Equation 1-3 Takt time .................................................................................................................. 4
Equation 4-1 Lead time ............................................................................................................... 14
Equation 4-2 Value added ratio................................................................................................... 14
Equation 4-3 Takt time ................................................................................................................ 16
Equation 5-1 Average level of effort............................................................................................ 57
Equation 5-2 Average of measure times..................................................................................... 57
Equation 5-3 Standard time ........................................................................................................ 57
Equation 6-1 Efficiency in line balancing .................................................................................... 60
Equation 6-2 Idle time in line balancing ...................................................................................... 60
Equation 6-3 Demand for manpower .......................................................................................... 61
Equation 6-4 Group efficiency..................................................................................................... 69
Equation 6-5 Group performance................................................................................................ 70
Equation 6-6 Personal efficiency................................................................................................. 70
Equation 6-7 Personal performance ........................................................................................... 71
Equation 6-8 Output volume according to HB............................................................................. 72

x


www.congnhemay.net

List of Abbreviations
ADO

ActiveX for Data Objects

AUTEX

Association of Universities for Textiles

CAD

Computer Added Design

DCT

Data Collection Terminal

DDE

Dynamic Data Exchange

FedEE

Federation of European Employers

FGI

Finished Goods inventory

GSD

General Sewing Standards

HB

Hugo Boss

HV

Hybrid Version

LM

Lean Manufacturing

MM

Modular Manufacturing

MTM

Motion Time Measurement

ODBC

Open Database Connectivity

OEE

Overall equipment effectiveness

OPEX

Operational Excellence

PBS

Progressive Bundle System

PFM

Performance Measures

RFT

Right-First-Time

SMED

Single minute exchange of die

SQL

Structured Query Language

SWOT

Strengths, Weaknesses, Opportunities & Threats

TEM

Total production maintenance program

TPM

Total productivity maintenance

TQM

Total Quality management

TPS

Toyota Production System

TSS

Toyota Sewn System Manufacturing Module Design

VR

Virtual Reality

VSM

Value Stream Mapping

WIP

Work-in-process / Work-in-progress

xi


www.congnhemay.net

xii

Preface
The dissertation is part of the two year postgraduate study program “European
Masters in Advanced Textile Engineering” which is organised by the Association of
Universities for Textiles. The thesis was written in the final semester at the Technical University Istanbul, Turkey.
As of now, the use of simulation programs in production processes in the textile
industry is rare. Production planning is practical oriented, rather based on state of
the art production planning techniques than on experience. The advantages a
simulation program could offer the user, are not widely known, so the interest in
investing in new techniques, with an eye on time and money, is low. The necessity
to improve the companies’ ways in production planning is often neglected. An important planning tool in production is line balancing. In this paper, the technique of
line balancing is combined with the use of a simulation program to show the possibilities and constraints of simulation in production line balancing.
The supervisors for this thesis are Prof. Dr. Fatma Kalaoğlu, Technical University
Istanbul, Turkey, and Prof. Mario de Araújo, University of Minho, Portugal.
Specially mentioned should be besides several other companies I visited, the
company Altınyıldız Mensucat ve Konfesiyon Fabrikaları. A.Ş., Istanbul, where I
was allowed to spend some weeks for time studies and research at the production
site and HUGO BOSS AG, Izmir, where I had the chance to spend one week for
research in state of the art production planning techniques at their plant in Izmir. I
would like to thank both companies for the cooperation and support during my
stay.
Special thanks to Mr. C. Enginar, who supported me during the work on my thesis,

especially when it came to Turkish language skills.

I would appreciate receiving the criticisms, corrections, and frank opinions of my
readers
().


xiii

www.congnhemay.net

Declaration
Herewith I declare that I have completed the present thesis by myself and without
the use of any aids other than those listed. All passages that were taken either
directly or mutatis mutandis from published and non-published sources have been
marked as such. The thesis has not been submitted to a different examination authority in the same or similar form.

Copyright: The author∗ gives admission to make this Master’s thesis available for
consultation and to copy parts of the Master’s thesis for personal use. Any other
use falls under the limitations of the copyright, especially with regard to the obligation of mentioning the source explicitly on quoting the results of this Master’s thesis.
The use of this paper regarding non-profit matters is without charge, a commercial
use in opposite needs agreement with the author. In addition, the author does not
take any responsibility for the correctness of the information in this paper.

Istanbul, 19th August 2008

Place, Date

∗

Signature

Author: Lina Rambausek, Email: Contact also through: Universiteit

Gent / Ghent University, Department of Textiles, Technologiepark-Zwijnaarde 907, 9052 Gent (Zwijnaarde), Belgium


www.congnhemay.net

Summary
The dissertation has been written in the fourth semester of the study program
“European Masters in Advanced Textile Engineering”, organised by the Association of Textile Universities (AUTEX). It will evaluate the use of simulation software
application in garment manufacturing industry with special reference to the use in
production line balancing. The usefulness of simulation software application in the
context of line balancing in garment manufacturing industry is considered. Additionally, I shall ascertain whether or not this technique might be successfully applied in garment manufacturing by conducting and observing a range of experiments.
Chapter 1 will give an overview of the topic and establish why using simulation
might be advantageous for textile companies. Further on, chapter 2 will outline the
aims and objectives of this dissertation and the 3rd chapter will address methodological issues.
In addition to simulation aspects, this paper will also examine issues concerning
Lean Manufacturing and the Toyota Production System (TPS). A comparison between manufacturing concepts is made in chapter 4. Here, the concepts of Progressive Bundle System (PBS), Modular Manufacturing (MM), Lean Manufacturing
(LM) and Mixed Manufacturing Module Design are discussed. A detailed description of the data base used for the experiments in further sections of this paper follows in chapter 5. The data collection was undertaken on the shop floor of a ladies’
jacket production line in Istanbul. The layout and the workflow of this particular line
was analysed and time studies are made.
Line balancing techniques are the topic of chapter 6. Here, information from state
of the art techniques in use is shown. How the production lines at the company
Hugo Boss in Izmir are balanced and general techniques for line balancing are
described in detail. Chapter 7 gives a presentation of the software “Enterprise Dynamics” which is used for the construction of the simulation model in chapter 8.
The chapter introduces us to current application fields of the software. The construction method of the simulation model is explained in chapter 8. In addition to
the setup process, this part deals with aspects of LM and degree of simplification
regarding the simulation model.

The experiments and its’ results are described closer in chapter 9. Six different
experiments with each a different line balancing strategy are conducted. The sections 9.6 and 9.8 summarize the result of the experiments and the outcomes of the
experiments are compared.


www.congnhemay.net

xv

The conclusion in chapter 10 contains a SWOT analysis which describes
strengths, weaknesses, opportunities and threats of the application of simulation
software in garment production and line balancing. Also future perspectives of the
application are discussed.


www.congnhemay.net

1

Introduction

Worldwide competition as part of the process of globalisation challenges garment
manufacturers in Europe. The considerable pressure to outsource production beyond the boarders of Europe increased with time. To remain competitive, hence to
sustain the option to produce in the western world, companies have to find their
competitive advantages in production processes.2
The potential yield of a strategic business unit, consequently, can be determined
by the difference between price and unit costs which are based on value-adding
and non-value-adding activities. Therefore the value of the product is defined by all
activities of the business unit.
This paper focuses on the ratio between value-adding and non-value-adding activities. Those either accomplish to cost advantage by influencing the situation of

costs of the business unit, or provide a basis for achievement in differentiation to
the competitor.
According to Kutz, Zerres and Zerres, value-adding activities are those activities,
which generate added value for the final customer and for which the customer is
willing to pay. Also, value-adding activities become comparative advantages in
competition in terms of differentiation on the basis of costs3
Customers are not longer willing to pay for non-value-adding production processes. Higher standards in quality and at the same time faster supply of products
are demanded.
In modern markets, customers demand: 4
•

The right product and its variations

Fashion trends are changing rapidly. The producer has to deal with a high variability in quantity, that means decreasing contract size, as well as with high
model diversity.
•

the best quality

As high-quality level and the best service are demanded, a need for more control emerged.
•

at the time needed

The manufacturer should be able to handle quick delivery, thus ensures a short
throughput-time at high productivity rates.
•

at a reasonable price.

www.congnhemay.net

2

The customer does not want to pay for things which do not add value to the
product, e.g. unnecessary transports.

To not reduce costs of production on account of the quality, to meet the pressure
on productivity and the shifted customer demands, companies need to find ways
to increase efficiency in production by other means. Time is a critical factor concerning labour-intensive manufacturing, as in garment production.5 So, how to
save money and time in the production procedure is a key issue which is tackled
by various companies in a number of ways. Some focus on radically changing the
production system to cut costs, others on increasing productivity and enhancing
quality, hence improving the existing system. 6
Clothing and textile production can be situated in less-developed countries. Labour-intensive but low-tech production methods contribute to the advantage in
production costs. In comparison, the necessity to decrease labour costs with hightech like information technologies and automation becomes more apparent in developed countries.7
As mentioned, low labour costs, are besides other cost factors, a major reason
why companies outsource production beyond the boarders of Europe. Even if high
labour costs in Europe are reasonable, to produce in a European country is an
expensive business. A list of gross minimum wage rates of countries textiles are
also produced in is shown in Appendix A.
Nevertheless, staying competitive, when producing garments in Europe, is of great
importance. Therefore the aim is to reduce the costs of labour per produced piece.
From history, it can be recognized that some companies tried to decrease these
costs by reducing the number of employees but this is, on the long run, the wrong
approach to the problem. The past of developed countries as well as today’s development in China show that as manufacturing productivity accelerates, industries loose jobs in manufacturing. The rise in productivity comes from improved
technologies and reallocation of resources.8 Nowadays rationalising the labour
force without labour replacement by technology attracts more and more notice
The better method to improve productivity is to use the available assets and workforce more efficiently. “Increasing productivity”, is the new mantra and no stone is

left unturned to improve processes in production and other business units.
The term productivity has a number of different definitions. In industry, it is most
commonly used with labour efficiency. In general productivity is the ratio of output
and input.


3

www.congnhemay.net

Productivity =

output
input
9

Equation 1-1 Productivity

Regarding labour, productivity may be defined as output per unit of time or output
per labour hour; it directly contributes to the productivity of the firm as the author
Mosser Barnes (1980) indicates.10
Labour productivi ty =

output
time
11

Equation 1-2 Labour productivity

Of course besides effectiveness of labour, other factors like the efficient operation

of machines, equipment, facilities and the economical use of materials affect productivity of the company and finally the production costs of the product.
As noted above, besides increasing labour productivity, also technological innovation can be considered to improve overall productivity. High tech-machines, automated production, or transport systems can be introduced into the production
process. Introduction of high-tech machinery costs time and is a capital investment, which in many cases the companies can ill afford.
The key is to start simple and investigate first the own production processes, to
finally find the scope where easy and quick changes can save money, time or increase quality. Many simple changes can sometimes exceed the success of a single complex one. This issue directs us to the practices of the car manufacture
Toyota and its production system TPS. It should be mentioned that Toyota derived
from a weaving company, hence the textile sector. One important issue in the context of the TPS is the avoidance of waste in all production process steps. The TPS
is a well-known and highly successive production system; it should be possible to
apply the ideas within the system in garment and textile industry also. To improve
garment production the companies should investigate manufacturing processes
from other fields and apply best practices from other industries, like car manufacturing.
Another approach to increase productivity is line balancing. Line balancing loss is
waiting time, which is caused by unbalanced or inadequate balanced production
line, expressed in no. of operators. That means, periods when the operator waits
for further work which is coming from workstations in the production line which
works in sequential steps. If the line is balanced well, the line balancing loss
should be at a minimum. Perfectly balanced lines with a line balancing loss of zero
operators are unusual. The calculation of Takt time helps the planner to schedule
the work stations.


4

www.congnhemay.net

Takt Time =

Time
units
12

Equation 1-3 Takt time

If all workstations work with the same Takt time and there are no interruptions in
production, then exactly one output unit is produced in the rhythm of Takt time.
For example, a company should produce 500 units per shift of 8 hours.

Takt time =

480 minutes 0,96 minutes
=
500 units
unit

The Takt time is 0.96 minutes. Every 0.96 minutes one output unit has to be produced to meet production schedule.

To find the optimum or an appropriate line balancing loss is certainly an issue
companies are focussing on. Planning tools in production line balancing attract
notice of an increasing number of companies. To keep the production labour costs
per produced piece as low as possible, companies try to increase efficiency in
workers assignment.
From my experience and knowledge that I gained during my studies, it appears to
be likely that:
•

If labour can be planned efficiently, production of garments is likely to be cost
effective even in countries with high labour costs.

•

Sewing is a labour intensive process hence reducing labour costs on the basis of carefully planning is likely to result in competitive advantage.

•

So far, companies in the textile sector do not use simulation as a tool for improving their production.

•

Garment production is one of the industrial branches, which does not seem to
attach a great deal of weight to production planning tools or other methods of
industrial engineering to increase productivity.

•

In production, trial and error methods are still common which seems to lessen
the degree of productivity which might be possible to achieve.

•

Companies remaining focussed on experience based knowledge which is
hard to transfer to other employees for example in if employees need to be
replaced.


www.congnhemay.net

5

More or less, still the system based on “experience based knowledge” works. In
case experience values get lost or can’t be developed further, production processes in real life situations could be complicated to deal with. In the textile sector

as in other producing industries, production planning tools are necessary to maintain and to improve productivity which arguably is a competitive advantage.
In other manufacturing industries, simulation of production processes is well established. Simulation is recognized as a powerful problem-solving tool which has its
roots in hard systems engineering like car manufacturing. In garment and clothing
manufacturing the application needs to be more extensive as modelling human
systems is more demanding and complex. Consequently a range of simplifications
have to be made to achieve a decrease in the complexity of human behaviour.13
The rationale for this paper lies in the observations and experiences within garment manufacturing processes cited above.
Chapter 2 and 3 describe the objectives of this thesis as well as show the method
completed in this thesis. A literature review regarding manufacturing concept is
given in chapter 4. The data base for construction the simulation in further chapters is discussed in chapter 5. Chapter 6 deals with the literature review concerning line balancing techniques. The software used for the experiments in chapter 9
is described in chapter 7. Chapter 8 contains a case study which is built upon data
gained during the research phase in this project. The content of this paper deals
with the topic production process, touches the matter of line balancing and the
theme simulation. Results of the empirical part of this work will be given in chapter
9. An overall evaluation of the application in line balancing in garment manufacturing will be discussed in chapter 10.


www.congnhemay.net

2

Objectives

Aim of this dissertation is to evaluate the use of simulation software in the process
of line balancing in garment manufacturing. The information is intended to give
users or future users of simulation software an overview of strengths and weaknesses in this special case of application.
Furthermore, this aims to make suggestions concerning possible problem resolutions during the first use of simulation software in line balancing. The experimental
approach in chapter 9, deals with several line balancing strategies.
The main subject of this dissertation focuses on line balancing in the context of
Lean Manufacturing, avoidance of non-adding value activities and constrains in

the usage of simulation software in line balancing in garment production.
Finally this paper is using SWOT analysis for the application of simulation software
in garment manufacturing in chapter 10. Advantages and Disadvantages of the
application of simulation software in production line balancing will be addressed.
Users of the information offered in this thesis should be aware that circumstances
of different production sites, of course, change the requirements of the application
of the software. The improvements within the experiments discussed are not the
only solutions valid for all production environments. Analysing a production process and building a simulation model go hand-in-hand with close investigation of
the conditions at the manufacturing site. Also, in order to avoid exceeding the
scope of this dissertation, the model in this paper is based on a number of simplifications, which will be explored later on. The dissertation is written within confines
of the subject of textile technology and therefore is not intended to challenge matters of industrial engineering and programming.


www.congnhemay.net

3

Approach

The aim of this paper is to evaluate application of simulation software when combined with the techniques of production line balancing. The SWOT analysis is
based on data collection on the production floor and through experimentation with
the simulation model derived from the data. Opportunities and constraints of the
use of simulation software in the context of line balancing are highlighted. Also
problems in setting up simulation models in the mentioned context are presented.
Following aspects will be investigated during the use of the simulation model.
•

output units and productivity,

•

status of the operator e.g. busy or idle,

•

number of units in inventory,

•

utility values of the single operations.

Of course, issues such as bottlenecks will be detected and analysed
The research plan is as follows:
1. Literature review and on-site research
2. Time studies
3. Work flow analysis
4. Simulation model set up
5. Simulation experiments with various techniques of line balancing
6. Evaluation of the usage of simulation software for the application in production line balancing

The actual procedural method to the final results in chapter 10, is shown in Fig.
3-1


8

www.congnhemay.net

Fig. 3-1 Procedural method

14


www.congnhemay.net

4

The Manufacturing Concepts

Due to the tremendous increase in speed of fashion changes during the last decades, garment production is challenged by many influencing factors. Besides
variations in product style, in material and accessories, variations in order quantities and quality aspects; the time to respond to the market can be the decisive factor to the success as garment manufacturer in Europe. Apparel manufacturers
have to experiment with new manufacturing concepts to meet the demand of the
market and hence, staying competitive. Three important manufacturing methods
are explained in the following sections. They are developed consecutively in time
and always build upon the previous manufacturing system. According to this approach, the mentioned advantages and disadvantages always refer to the previous
concept.

4.1

Progressive Bundle System (PBS)15

4.1.1 Concept
Each operator is assigned to only one machine, performing a single operation repetitively. Through the production line, the parts are passed on in bundles of for
example 25 pieces per bundle.

4.1.2 Advantages of PBS
•

If rework needs to be done the responsibilities are clear. Each worker is responsible for the operation fulfilled.

•

The operator’s work is easy controllable in means of payment terms e.g.
piece rate.

•

Large order quantities or mass production is realizable with this system.

4.1.3 Disadvantages of PBS
•

The higher the number of pieces within the bundle the higher is the value of
WIP, the longer is the throughput time with regard to the time the products
wait in the inventory section.

•

Quality inspections are generally made at the end of the line. At this point of
the line, the repair can get more complex due to the whole garment needs
to be unpicked to rectify a fault made early in the production stage. Hence,
more time is needed for rework.