increasing efficiency of line m123 through the …

i

INCREASING EFFICIENCY OF LINE M123

THROUGH THE APPLICATION OF TIME STUDY

AND LINE BALANCING METHOD

(CASE STUDY AT PT XY)

By

Muhammad Arif

ID No. 004201200023

A Thesis presented to the

Faculty of Engineering President University in partial

fulfillment of the requirements of Bachelor Degree in

Engineering Major in Industrial Engineering

2016

ii

THESIS ADVISOR

RECOMMENDATION LETTER

This thesis entitled “Increasing Efficiency of Line M123 Through the

Application of Time Study and Line Balancing Method (A case study in PT

XY)” prepared and submitted by Muhammad Arif in partial fulfillment of the

requirements for the degree of Bachelor Degree in the Faculty of Engineering has

been reviewed and found to have satisfied the requirements for a thesis fit to be

examined. I therefore recommend this thesis for Oral Defense.

Cikarang, Indonesia, January 28th

, 2016

Herwan Yusmira, Bsc. MET, MTech.

iii

DECLARATION OF ORIGINALITY

I declare that this thesis, entitled “Increasing Efficiency of Line M123 through

the Application of Time Study and Line Balancing Method (A case study in

PT XY)” is, to the best of my knowledge and belief, an original piece of work

that has not been submitted, either in whole or in part, to another university to

obtain a degree.

Cikarang, Indonesia, January 28th

, 2016

Muhammad Arif

iv

INCREASING EFFICIENCY OF LINE M123

THROUGH THE APPLICATION OF TIME STUDY

AND LINE BALANCING METHOD

(A case study in PT XY)

By

Muhammad Arif

ID No. 004201200023

Approved by

Herwan Yusmira, B.Sc. MET, MTech Ir. Andira, MT

Thesis Advisor 1 Thesis Advisor 2

Ir. Andira, MT

Program Head of Industrial Engineering

v

ABSTRACT

The focus of this research is to increase the line efficiency of line M123. The root

causes of having low efficiency itself are less accuracy and poor work

arrangement. Because of that, the output is not match the target and overtime must

be done. To overcome the problem, the root cause must be attacked by firstly

doing the time study prior the other method to be done. An accurate standard time

is expected to make the number of operator adequate and designing the work

arrangement smoothly without violating the takt time. To deal with a proper work

arrangement, line balancing method is used. The result shows that the efficiency

can be increased by 32.89% from previously 57.11% to 90%. The target output

can also be achieved together with the reduction number of operator. Thus, the

cost can be minimized.

Keywords: line efficiency, time study, standard time, line balancing, work

arrangement, cycle time, takt time

vi

ACKNOWLEDGEMENT

This thesis has never been done without my own effort and some supports from

people around me. Thus, I want to send my gratitude to Allah SWT for having

these guys around me.

1. Mom and Dad, thank you for all the things that you have given to me. I

would never run until this far without you in my life.

2. Kak Nova, kak Ira, and the Baby Sajid Ahnaf. You guys are one of my

reasons to keep me fighting for this thesis.

3. My lecturers, Mam Andira, Mam Anastasia, and Sir Herwan Yusmira.

Thank you for guiding me during my college life.

4. LSC department of PT XY, Cr, Mr K, Mr J, Ms B, Ms D, Ms DD, and Ms

A. Thanks for always surrounding myself with knowledge and cheers. You

guys contribute a lot in my life. Thanks for “Kaizen-ing” myself.

5. QA department of PT. MEAINA, thanks for accepting me in your

circumstances in my 1st Internship period.

6. Novando, Vero, Mr T and Mr R. Thanks for helping me finish this thesis.

7. Dudy, Fathur, Putera, Farhan, Aidil, Yoyo, and Rifi. I just feel you guys

are worth to be written here.

8. Generation of Eight (Genoit), there is none of my printed achievement

without the “Genoit” name in it.

9. Engineering 2012, thanks for the 3,5 years of togetherness and support.

vii

TABLE OF CONTENT

THESIS ADVISOR RECOMMENDATION LETTER ......................................... i

DECLARATION OF ORIGINALITY .................................................................. iii

LETTER OF APPROVAL ..................................................................................... iv

ABSTRACT ............................................................................................................ v

ACKNOWLEDGEMENT ..................................................................................... vi

TABLE OF CONTENT ........................................................................................ vii

LIST OF TABLE .................................................................................................... x

LIST OF FIGURES .............................................................................................. xii

LIST OF TERMINOLOGIES .............................................................................. xiii

CHAPTER I INTRODUCTION ............................ Error! Bookmark not defined.

1.1 Problem Background .................................... Error! Bookmark not defined.

1.2. Problem Statement ...................................... Error! Bookmark not defined.

1.3 Objectives ..................................................... Error! Bookmark not defined.

1.4 Scope ............................................................ Error! Bookmark not defined.

1.5 Assumption .................................................. Error! Bookmark not defined.

1.6 Research Outline .......................................... Error! Bookmark not defined.

CHAPTER II STUDY LITERATURE .................. Error! Bookmark not defined.

2.1. Time study ................................................... Error! Bookmark not defined.

2.1.1 Rating Performance ............................... Error! Bookmark not defined.

2.1.2 Normal Time ......................................... Error! Bookmark not defined.

2.1.3 Allowance ............................................. Error! Bookmark not defined.

2.1.4 Standard Time ....................................... Error! Bookmark not defined.

2.2 Data Validity Testing ................................... Error! Bookmark not defined.

2.2.1 Normality Test ...................................... Error! Bookmark not defined.

2.2.2 Uniformity Test ..................................... Error! Bookmark not defined.

2.2.3 Sufficiency Test .................................... Error! Bookmark not defined.

2.3 Operation Process Chart ............................... Error! Bookmark not defined.

2.4 Line Balancing ............................................. Error! Bookmark not defined.

2.4.1 Methods of Line Balancing ................... Error! Bookmark not defined.

2.4.2 Measurement of Line Balancing ........... Error! Bookmark not defined.

CHAPTER III RESEARCH METHODOLOGY .. Error! Bookmark not defined.

viii

3.1 Initial Observation ........................................ Error! Bookmark not defined.

3.2 Problem Identification .................................. Error! Bookmark not defined.

3.3 Literature Study ............................................ Error! Bookmark not defined.

3.4 Data Collection and Analysis ....................... Error! Bookmark not defined.

3.4.1 Data Collection...................................... Error! Bookmark not defined.

3.4.2 Data Analysis ........................................ Error! Bookmark not defined.

3.5 Application of Line Balancing Method ....... Error! Bookmark not defined.

3.6 Conclusion and Recommendation................ Error! Bookmark not defined.

3.7 Research Framework .................................... Error! Bookmark not defined.

CHAPTER IV DATA COLLECTION AND ANALYSISError! Bookmark not

defined.

4.1 Initial Line Efficiency .................................. Error! Bookmark not defined.

4.2 Analyzing Root Cause of Low Efficiency ... Error! Bookmark not defined.

4.2.1 Observing the Standard Determined by CompanyError! Bookmark

not defined.

4.2.3 Number of Operator .............................. Error! Bookmark not defined.

4.3 Standard Time at M123 ................................ Error! Bookmark not defined.

4.4 Standard Time before Time Study ............... Error! Bookmark not defined.

4.5 Actual Standard Time .................................. Error! Bookmark not defined.

4.5.1 Normality Test ...................................... Error! Bookmark not defined.

4.5.2 Uniformity Test ..................................... Error! Bookmark not defined.

4.5.3 Sufficiency Test .................................... Error! Bookmark not defined.

4.5.4 Performance Rating ............................... Error! Bookmark not defined.

4.5.5 Normal Time ......................................... Error! Bookmark not defined.

4.5.6 PFD (Personal, Fatigue, and Delay) ...... Error! Bookmark not defined.

4.5.7 Standard Time ....................................... Error! Bookmark not defined.

4.6 Line Balancing ............................................. Error! Bookmark not defined.

4.6.1 Largest Candidate Rule ......................... Error! Bookmark not defined.

4.6.2 Killbridge and Wester Method .............. Error! Bookmark not defined.

4.6.3 Rank Positional Weight ........................ Error! Bookmark not defined.

4.7 Comparison of Three Methods..................... Error! Bookmark not defined.

4.7.1 Balance Delay ....................................... Error! Bookmark not defined.

4.8 Additional Action ......................................... Error! Bookmark not defined.

4.9 Final Evaluation ........................................... Error! Bookmark not defined.

ix

4.9 Comparison of Current and Proposed Line .. Error! Bookmark not defined.

CHAPTER V CONCLUSION AND RECOMMENDATIONError! Bookmark

not defined.

5.1 Conclusion ............................................... Error! Bookmark not defined.

5.2 Recommendation ..................................... Error! Bookmark not defined.

REFERENCES ....................................................... Error! Bookmark not defined.

APPENDICES ....................................................... Error! Bookmark not defined.

Appendix 1 OPC Before ........................................ Error! Bookmark not defined.

Appendix 2 OPC After ........................................... Error! Bookmark not defined.

Appendix 3 Criteria of Skill and Effort ................. Error! Bookmark not defined.

Appendix 4 Performance Rating Calculation ........ Error! Bookmark not defined.

Appendix 5 Result of Time Study ......................... Error! Bookmark not defined.

Appendix 6 Sufficiency Test .................................. Error! Bookmark not defined.

Appendix 7 Comparison Table between the before and after observation .... Error!

Bookmark not defined.

Appendix 8 Rank Position Weight Matrix ............. Error! Bookmark not defined.

Appendix 9 Supporting Tools ................................ Error! Bookmark not defined.

x

LIST OF TABLE

Table 2. 1 Performance Rating .............................. Error! Bookmark not defined.

Table 2. 2 Effort Rating ......................................... Error! Bookmark not defined.

Table 2. 3 Condition Rating ................................... Error! Bookmark not defined.

Table 2. 4 Consistency Rating ............................... Error! Bookmark not defined.

Table 2. 5 Performance Rating Calculation ........... Error! Bookmark not defined.

Table 2. 6 Largest Candidate Rule Table Example Error! Bookmark not defined.

Table 2. 7 Table of Task Assigned Using LCR MethodError! Bookmark not

defined.

Table 2. 8 Killbridge and Wester's Method ExampleError! Bookmark not

defined.

Table 2. 9 Determined Work Station ..................... Error! Bookmark not defined.

Table 2. 10 Ranked Positon Weight Method ......... Error! Bookmark not defined.

Table 2. 11 Determined Work Station ................... Error! Bookmark not defined.

Table 4.1 Current Line Efficiency ......................... Error! Bookmark not defined.

Table 4. 2 Standard time before time study ........... Error! Bookmark not defined.

Table 4. 3 Performance of Operator 1 .................... Error! Bookmark not defined.

Table 4. 4 Actual Standard Time ........................... Error! Bookmark not defined.

Table 4. 5 Precedence Table .................................. Error! Bookmark not defined.

Table 4. 6 Precedence Table (continued) ............... Error! Bookmark not defined.

Table 4. 7 Proposed Work Station ......................... Error! Bookmark not defined.

Table 4. 8 Evaluation of LCR ................................ Error! Bookmark not defined.

Table 4. 9 Killbridge and Wester Method .............. Error! Bookmark not defined.

Table 4. 10 Evaluation of KWM ............................ Error! Bookmark not defined.

Table 4. 11 Work Station of RPW Application ..... Error! Bookmark not defined.

Table 4. 12 Smoothness Index of RPW ................. Error! Bookmark not defined.

Table 4. 13 Cycle time of attaching head ............... Error! Bookmark not defined.

Table 4. 14 New cycle time of work station 14 ..... Error! Bookmark not defined.

Table 4. 15 New cycle time for work station 17 .... Error! Bookmark not defined.



xi

Table 4. 18 New cycle time for work station 3 ...... Error! Bookmark not defined.



Table 4. 21 New cycle time for each work station . Error! Bookmark not defined.

Table 4. 22 Evaluation of Final Work ArrangementError! Bookmark not

defined.

Table 4. 23 The result of improvement .................. Error! Bookmark not defined.

Table 4. 24 Cost comparison between actual and after improvement condition

................................................................................ Error! Bookmark not defined.

xii

LIST OF FIGURES

Figure 2. 1 Example of Operation Process Chart ... Error! Bookmark not defined.

Figure 2. 2 Precedence Diagram ............................ Error! Bookmark not defined.

Figure 2. 3 Work Station Determined Using KWM MethodError! Bookmark not

defined.


Figure 2. 5 Determined Work Station .................... Error! Bookmark not defined.

Figure 3. 1 Research Flow ..................................... Error! Bookmark not defined.

Figure 3. 2 Research Framework ........................... Error! Bookmark not defined.

Figure 4. 1 Fishbone Diagram of Root Cause AnalysisError! Bookmark not

defined.

Figure 4. 2 Yamazumi of Labor Data Sheet .......... Error! Bookmark not defined.

Figure 4. 3 Actual time vs LDS time ..................... Error! Bookmark not defined.


Figure 4. 5 Yamazumi Chart of LCR Method ApplicationError! Bookmark not

defined.

Figure 4. 6 Proposed Layout of Largest Candidate RuleError! Bookmark not

defined.

Figure 4. 7 Killbridge and Wester Method ............ Error! Bookmark not defined.

Figure 4. 8 Yamazumi Chart of KWM .................. Error! Bookmark not defined.

Figure 4. 9 Yamazumi Chart of RPW method applicationError! Bookmark not

defined.

Figure 4. 10 Proposed Layout of Rank Position WeightError! Bookmark not

defined.

Figure 4. 11 Balance Delay Comparison ............... Error! Bookmark not defined.

Figure 4. 12 Efficiency Comparison ...................... Error! Bookmark not defined.

Figure 4. 13 Smoothness Index Comparison ......... Error! Bookmark not defined.

Figure 4. 14 Chosen Yamazumi Chart of RPW ApplicationError! Bookmark not

defined.

Figure 4. 15 Improved Yamazumi Chart ............... Error! Bookmark not defined.

xiii

Figure 4. 16 Comparison between current and proposed lineError! Bookmark

not defined.

xiv

LIST OF TERMINOLOGIES

Efficiency : the comparison of what is actually produced with

what can be achieved with the same consumption of

resources

Line balancing : the process of assigning tasks to workstations in such

a way that the workstation have approximately equal

time requirement

Balance delay : the amount of idle on production assembly lines

caused by the uneven division of work among

operators and stations

LDS : Labor Data Sheet; a data that gives information

about the target output, takt time, number of

operators, and work arrangement

Cycle time : the period required to complete one cycle of an

operation, or to complete a function, job, or task

from start to finish

Lead time : the amount of time between the placing of an order

and the receipt of the goods ordered

Normal time : the amount of time required for a repeated operation

by an experienced worker of average skill working at

a normal pace

OPC : Operation Process Chart ; a graphical representation

of the sequence of steps constituting a process, from

raw materials through to the finished product

Performance rating : a process to evaluate the performance of the

operators

Precedence diagram : a visual representation techniques that depicts the

activities involved in a project and the dependencies

among those activities

xv

Significance level : the probability that the test will reject null hypothesis

when the hypothesis is true

Smoothness index : a scale that shows the extent level of smoothness of

the production line

Standard time : the time for completing the work process with

allowance

Takt time : the amount of time necessary to build one unit to

satisfy customer demand

Time study : the examination and analysis of time and motion

required to complete an action

Yamazumi chart : a stacked bar chart that shows the balance of cycle

time workloads between a number of operators

typically in an assembly line or work cell

ABSTRACT

The focus of this research is to increase the line efficiency of line M123. The root

causes of having low efficiency itself are less accuracy and poor work

arrangement. Because of that, the output is not match the target and overtime must

be done. To overcome the problem, the root cause must be attacked by firstly

doing the time study prior the other method to be done. An accurate standard time

is expected to make the number of operator adequate and designing the work

arrangement smoothly without violating the takt time. To deal with a proper work

arrangement, line balancing method is used. The result shows that the efficiency

can be increased by 32.89% from previously 57.11% to 90%. The target output

can also be achieved together with the reduction number of operator. Thus, the

cost can be minimized.

Keywords: line efficiency, time study, standard time, line balancing, work

arrangement, cycle time, takt time

CHAPTER I

INTRODUCTION

1.1 Problem Background

Efficiency is something essential for a company especially for the company

running a mass production business and utilizes much kind of resources. Having a

good efficiency will be very beneficial. High efficiency means all the resources

such as human, material, space, and machines are well utilized. There is no excess

and the waste is minimized. By having such these things, the cost can

automatically be properly-allocated and minimized. These benefits can strength

the position of the company in the business competition. Producing maximal

output with a short lead time and fulfilling the demand of customers are

something that every company has dreamt of.

PT XY that will be called PT XY for the next is one of multinational company in

Indonesia. This company is one of the biggest toy manufacturing in the world.

The main focus of the company’s activities is producing dolls. The dolls

manufactured are mainly distributed to America and Europe continent. These two

continents give a very big impact to the sales rating especially when Halloween

and Christmas. These two occasions are the condition where people usually tend

to give present. This is the main consideration of head quarter in determining the

order number that must be fulfilled by PT XY.

A good efficiency is very important for PT XY as the subsidiary. PT XY must be

able to manage the resource well in order to fulfill the demand given by

headquarter. The demand will be very high at certain period. In this case, of

course the head quarter do not want to lose the opportunity and will ask PT XY to

deliver the product at the very right time. This will help PT XY in minimizing

cost for the excessive stuff such as inventory, labor, and machine utilization. That

is why efficiency is way very important for PT XY.

There are three major process in manufacturing the dolls; primary process, sewing

process, and secondary process. The primary process is the process where basic

part of dolls is made such as torso. Primary process also includes the rooting

process. Sewing process includes costume development and costume sewing

production. The last is secondary process which is also called final assembly

process where the dolls and its accessories are packed. Those are the three major

processes at PT XY.

As one of leading doll manufacturing company, PT XY has always targeted a high

standard for efficiency. Thus, every production line at PT XY is automatically

expected to have good efficiency. Last year, the efficiency target of PT XY was

81%. This year, the company levels the efficiency up to 90%. It means that every

production line at PT XY should have minimum efficiency of 90% to support the

company’s goal.

The fact, some of the production lines at PT XY still have line efficiency below

90% especially at line M123. At week ending 10/12/2015, the line efficiency

touches the number of 57%. It is way far from the target established by the

company and it cost for excess or shortages. Based on the efficiency target, this

production line does not fulfill the standard established by PT XY. Looking at this

problem, thus it is needed to increase the line efficiency since the demand can

sometimes be very high for several products. Through this thesis, it is expected

that line production can achieve the efficiency target set by PT XY.

1.2. Problem Statement

Based on the background explanation above, several problem statements can be

conducted:

What is the root cause of low efficiency at line M123?

How to increase the line efficiency at line M123?

1.3 Objectives

There is an objective to be achieved through this research

To improve efficiency of line M123

1.4 Scope

Due to the limitation of resources, the scope of this research will be limited:

Head Count Addition or Head Count Elimination can only be done by

secondary area management

The observation is done from October 12th

– October 15th

2015

1.5 Assumption

Assumptions must be made in this research to create an appropriate model.

The skill of operators are assumed to be the equally-likely

The target of output is equal during observation

Material are always available during production process

1.6 Research Outline

Chapter I Introduction

This chapter includes the problem background,

research questions, objectives, scope and limitation of

the research as well as the research outline.

Chapter II Study Literature

This chapter includes study time study, line balancing,

and other tools that can support this final project.

Chapter III Research Methodology

All systematic steps and detailed framework are

provided in this chapter to arrange this research to be

conducted methodically. The framework is made

regarding the literature study as well.

Chapter IV Data Analysis

The data that have been collected will be analyzed

through this chapter. The main result will be the new

arrangement of the work station that is expected to

increase efficiency.

Chapter V Conclusion and Recommendation

This chapter includes the summary of the research

together with the recommendation for the future

research.

Through this chapter, the problem and objectives of the research have been

clearly-stated together with the scope and assumptions. Thus, this research has

gotten its direction in the process of achieving the objectives. To meet the

objectives, it needs also to find a way to solve the problem. Therefore, some

literature about related subject will be delivered in the next chapter.

CHAPTER II

STUDY LITERATURE

2.1. Time study

It is important to tally the real time to complete procedures in the generation line.

This should be possible by utilizing an instrument, for example, stopwatch. Along

these lines it is called stopwatch time study. There are two systems in working

with this stopwatch, back to back timing technique and snapback strategy. While

persistent timing strategy permits the stopwatch to keep running for the whole

span of study, snapback system breaks the procedure into components. Sometime

study investigator use both routines, trusting that 9 studies dominatingly long

components are more versatile to snapback readings, while short cycle studies are

more qualified to the nonstop strategy (Niebel, 2003).

At the point when parts of time study contains a wide differing qualities of

systems to focus the measure of time needed, under an astounding estimation of

the state, for work related with the human, machine, or a mix of both. It is has

been presented by Frederick W. Taylor since the year 1881, yet is still generally

utilized as a technique for time study. For the most part, time study is utilized to

gauge work. The choice results than the time study is the period in which an

individual as per work or errand and completely prepared to use particular system,

will perform this errand if the specialist in the typical or master. This is known as

the time standard for operation. Adjust the master for a work may be made

through a few routines, where every Method is utilized just as per some particular

circumstances. Time study is incorporate utilizing stopwatch, 'Foreordained

Motion Time System or Synthetic Time System', and 'Work or Action Sampling".

On the other hand, in this study, just the time study utilizing Stopwatch Time

Study will be utilized as a part of the time estimation. The time study was

additionally permitted to deduct all visitors. Institutionalization is the target to be

accomplished. These insights may be demonstrated by the work inspecting

operation. On the off chance that standard set, execution enhanced to normal 85%.

This is a 42% increment in execution.

2.1.1 Rating Performance

The performance of operator can exactly be affected by several factors especially

during the production process. Considering that, in calculating standard time,

performance rating of operator needs to be considered too. Westinghouse Electric

Corporation has made a rating system to evaluate the performance level of the

operator. That system is known as Westinghouse Rating System. The performance

evaluation is done based on four aspects which are skill,effort, condition, and

consistency.

Skills is proficiency at following a given method or instruction and further relates

it to expertise, as demonstrated by the proper coordination of mind and hands

(Niebel, 2003). Effort is the speed with which skill applied, and can be controlled

to a high degree by the operator. While evaluating the effort of the operator, only

effective effort need to be rated because the operator may intentionally do some

misdirected effort to increase the cycle time. The terms of condition refers to the

situation and facility that have impact to the operator such as noise level,

temperature, ventilation, light, and etc. The last thing to be evaluated is the

consistency. By having data observation, the observer is able to review the work

progress of each operator. That work progress can be used as a measurement to

determine the consistency of the operator. Westinghouse rating system table can

be seen as below

.

Table 2. 1 Performance Rating

Table 2. 2 Effort Rating

+0.13 A1 Excessive

+0.12 A2 Excessive

+0.1 B1 Excellent

+0.08 B2 Excellent

+0.05 C1 Good

+0.02 C2 Good

0 D Average

-0.04 E1 Fair

-0.08 E2 Fair

-0.12 F1 Poor

-0.17 F2 Poor

Table 2. 3 Condition Rating

+0.06 A Ideal

+0.04 B Excellent

+0.02 C Good

0 D Average

-0.03 E Fair

-0.07 F Poor

+0.15 A1 Superskill

+0.13 A2 Superskill

+0.11 B1 Excellent

+0.08 B2 Excellent

+0.06 C1 Good

+0.03 C2 Good

0 D Average

-0.05 E1 Fair

-0.1 E2 Fair

-0.16 F1 Poor

-0.22 F2 Poor

Table 2. 4 Consistency Rating

+0.04 A Perfect

+0.03 B Excellent

+0.01 C Good

0 D Average

-0.02 E Fair

-0.04 F Poor

Karger (1977) provides the criteria of skill and effort. The criteria provided are

able to help the operators to rate the operators. For more detail, it can be seen on

appendices.

After finishing the performance evaluation, the ratings from those factors can be

summed up. For more detail, the table below provides the example of calculation

for the performance factor. The result of this calculation

Table 2. 5 Performance Rating Calculation

Skill C2 +0.03

Effort C1 +0.05

Condition D +0.00

Consistency E -0.02

Algebraic Sum +0.06

Performance Rating 1.06

Some companies have modified the application of Westinghouse system. Some

thought stated that in certain condition, the value can be rated as zero value. It

means there is no impact to the performance of operators. While consistency is

related to skills, thus the value of consistency is no longer counted. Therefore,

conditions and consistency are omitted as the factors in determining the

performance rating.

2.1.2 Normal Time

Normal time is the measure of time needed for a repeated operation by a trained

worker of normal expertise working at an ordinary pace. It is come about because

(2-1)

(2-2)

of the augmentation between watched time and execution rating of the operator

(Niebel, 2003).

2.1.3 Allowance

Fundamentally, allowance is divided into three classes which are constant

allowance, variable allowance, and special allowance. Constant allowance can be

defined as the time dealt by operator to take care of personal needs. This basic

allowance is an initial allowance for operator. Except the personal issues, the

operator may have another issue from external factors that will affect the

performance of operator. This tolerance is covered by variable fatigue allowance.

Special allowance is the tolerance time to deal with external factors that have no

impact to the operator but to the operation such as to the equipment and material.

Those are the categories of allowance.

2.1.4 Standard Time

After calculating the PFD (Personal, Fatigue, and Delay) allowance, the standard

time can be established. The term of standard time is the time needed for a

completely qualified, prepared operator, working at standard pace and applying

normal exertion, to perform the operation (Niebel, 2003).

2.2 Data Validity Testing

2.2.1 Normality Test

It is important to know whether the data is normally distribute or not, meaning

that the statistical inference must be determined. There are two options in creating

statistical inference; they are confidence interval or hypothesis testing. In

confidence interval, it means that the population is unknown (Hayter, 2000).

(2-4)

(2-3)

There are some equation can be utilized to focus the ordinariness of an

arrangement of information, one of them is by utilizing p-esteem. The speculation

comprises of two announcements, invalid theory (H0) and option theory (HA).

Invalid speculation is an announcement of a zero or invalid contrast that is

straightforwardly tried. This will relate to the first claim if that claim incorporates

the state of no change (=) or contrast, for example, ≥ or ≤. Invalid speculation is

tried straightforwardly since the last conclusion will be either dismissal of H0 or

inability to dismiss H0 (Walpole, 2002). On the off chance that H0 is rejected,

then HA must be valid.

With a specific end goal to check the typicality of the dissemination, the null

hypothesis (H0) and alternative hypothesis (HA) must be expressed as underneath

H0: The data is normally distributed

HA: The data is not normally distributed

2.2.2 Uniformity Test

Beside the normality, uniformity of data must also be checked. One collection of

data can pass the normality test but sometimes the variance is too big. Thus, the

data is significantly different between one and another. Then, the limit must be

created through this test to ensure the separation is still in the desired level. If it is

out of the control limit, then the out-of-limit data must be omitted. This is the step

to determine the uniformity of data:

a. Calculate average observed time (x) for each operation

b. Calculate the standard deviation (s) of each operation (Wignjosoebroto, 2000).

(2-5)

(2-6)

c. Focus the Upper Control Limit (UCL) and Lower Control Limit (LCL)

(Wignjosoebroto, 2000). This point of confinement will decide how uniform

the information each other. The littler the farthest point, the more the

information will be uniform. More than 99% of the region under any typical

dispersion is encased in the reach that known as six sigma limits (Taha, 1987).

The following is the recipe to focus UCL and LCL in six sigma limits.

2.2.3 Sufficiency Test

The purpose of sufficiency test is to find how much observation needed to reach

the confidence level. Thus, the more the variance of data, the more observation

needed. The following formula can calculate how much observation needed to

achieve 95% confidence level (Sutalaksana, 2006). N’ is the number observation

that must be done. The data is considered enough when n (number of data) is

bigger than N’.

2.3 Operation Process Chart

Operation process chart is a diagram depicting the steps of assembling material,

started from raw material until component or finished product. Operation process

chart contain information for further analysis.

Time wasted, material used, and the space or machine utilized for material

processing. So, in one complete Operation Process Chart, the recorded processes

are operation and inspection, storing will sometimes be put at the end of the

process.

For more complete comprehension of Operation Process Chart, the following

figure is the complete process of telephone manufacturing starting from the

assembling the component until the final inspection of finished product.

Source: Niebel's Methods, Standards, and Work Design 12th Edition

Figure 2. 1 Example of Operation Process Chart

2.4 Line Balancing

2.4.1 Methods of Line Balancing

Line balancing means balancing the production lines or assembly lines. The

principle goal of line balancing is to set the assignment uniformly over the work

station with the goal that sit without wasted time of man or machine can be

minimized. Line balancing goes for gathering the laborers in an effective example

with a specific end goal to get an ideal or most effective equalization of the

capacities and the flow of the process or assembly process.

Line balancing is also known as a term to process of determining the tasks in a

work stations in a production sequences. The tasks itself consist of the necessary

operations to convert the raw material to finished goods. Line balancing is a

classic operation of optimization technique having a very significant effect to

industries especially in applying the lean concept. The principle of mass

production is involving line balancing of assembling the similar components or

changing components in different production level of work station. As the

knowledge about line balancing is getting better, perfection and in line balancing

procedure is being continuously developed and it is a must for the sake of

industries. The proficient work allocation is purposed to achieve a good efficiency

and productivity.

There are several method used to balance the production lines. Three method of

line balancing will be explained through this literature study. The methods are

Largest Candidate Rule (LCR), Killbridge and Wester’s Method (KWM), and

Ranked Positional Weight Method (RPW).

2.4.1.1 Largest Candidate Rule (LCR) Method

It is known that the main purpose of line balancing is to distribute the total

workload evenly and smoothly although in fact, it is impossible to achieve the

perfect balancing among workers. This is the role of line balancing efficiency

related to differences in minimum rational work element time and the precedence

constraints between the elements. Largest Candidate Rule method arranges the

work element in a descending order (referred to the work station and work

element) for each work station and not exceeding the allowable precedence.

Below is the example of Largest Candidate Rule Application in balancing the line.

Table 2. 6 Largest Candidate Rule Table Example

Source: Line Balancing Using Largest Candidate Rule Algorithm in a Garment Industry

An assignment should be possible by machines of diverse sorts furthermore by

administrators of distinctive work sorts. The handling time of any errand is a

variable controlled by the expertise level also, productivity of the administrator.

The work is isolated in a manner that every administrator gets equivalent work

load. The applied system proposed and quickly abridged in the going before

segment fills the need of exhibiting how the proposed system would work. Table

above portrays the work components organized by. At that point figure above

demonstrates the Operator line adjusting graph after the line adjusting procedure

and the administrator process durations have been expanded by giving the laborers

additional operations and the unmoving times of the specialists was decreased and

to enhance the productivity. Thus the operation was handled by 16 workers is just

reduced by 50 % to 8 workers. Line balancing Efficiency (to be) = 85.5%

Table 2. 7 Table of Task Assigned Using LCR Method

Source: Line Balancing Using Largest Candidate Rule Algorithm in a Garment Industry

Above is the table of arrangement of the workstation after the balancing process

based on the Largest Candidate Rule (LCR) method.

2.4.1.2 Killbridge and Wester’s Method (KWM) Method

Kilbridge and Wester (segment) system is a heuristic method that chooses work

components for task to stations as indicated by their positions in the precedence

diagram. This techniques known for its unwavering quality in conquering the

troubles, for example, experienced in Largest Candidates Rule system where a

component could be chosen as for high Te Value however independent of its

position in the priority outline. However in the section technique the components

are arranged into columns.

Table 2. 8 Killbridge and Wester's Method Example

Source: Selection of Balancing Method for Manual Assembly Line of Two Stages Gearbox

Above is the example of Killbridge and Wester’s method example. It includes the

work element of the lines together with its cycle time for each work element.

There will also the determination of column for each work element. The

precedence of each work element must be put there on the table.

Table 2. 9 Determined Work Station


Above is the result table of Killbridge and wester’s method. On the table, the

work elements have been put in order based on the time and the work stations

have been established. For each work station, the time will not be exceeded the

Takt time. Based on table, the tasks can be grouped into four work stations.

Figure 2. 2 Precedence Diagram


Figure 2. 3 Work Station Determined Using KWM Method


2.4.1.3 Ranked Positional Weight Method

Ranked Positional Weight method is used to calculate for each element. The

method accounted the Takt time value and the position at the precedence diagram.

RPW is computed by summing Takt time and other time for the element that

follow the takt time in the arrow of precedence diagram. Then, the time is

rearranged using the previous step. The work element can be seen at the table

below and the table can also be generated using RPW table. The idle time was set

to be 0 second for Station 2 with 1, 5 and 3 seconds for stations 1, 3 and 4 as it is

on the figure below. In this case, Station 2 is the bottleneck station.



Above is the example of precedence diagram in one sequence of production for an

assembly line. Each of the work elements is preceded by some or one work

elements. Then, it should be made in sequence to make it order and easier to work

stationing process.

Figure 2. 5 Determined Work Station


Above is the output after balancing the process using the Ranked Positional

Weight method. The result of the method state that the tasks can be grouped in to

four stations. Each station consists of some tasks that can be done by one operator.

Table 2. 10 Ranked Positon Weight Method

Table 2. 11 Determined Work Station


The tables above are the sequence of the operation that is put on the tables. The

first table above shows the precedence task of another task together with the

weighted value for each work element. The takt time is also put there.

After determining the table of precedence and takt time, then the next step is

making the table consist of the established work station based on the Ranked

Positional Weight Method.

2.4.2 Measurement of Line Balancing

2.4.2.1 Takt Time

Takt time is characterized as the measure of time important to fabricate one unit to

fulfill client interest (Till, 2010). Each procedure must be finished in under takt

time unless the yield of creation won't meet the arranging calendar. Net accessible

time and every day request must be resolved before computing takt time. Net

accessible time is the measure of time accessible for work to be finished. This

(2-7)

(2-8)

(2-9)

rejects break times and any normal stoppage time, for example, planned support,

group briefings, and meal break. Takt time is characterized by this equation below

2.4.2.2 Yamazumi Chart

A Yamazumi outline is a stacked bar graph that demonstrates the parity of process

duration workloads between various administrators regularly in mechanical

production system or work cell (Minkjan, 2009). This graph will likewise

distinguish whether any procedure surpass takt time or not. In this way, the

quantity of yield every day could likewise be anticipated.

2.4.2.3 Number of Operator

In the wake of figuring the standard time, the measure of operator number must be

chosen (Elsayed, 1985).

Where:

Ti = time from process 1-k

Tt = takt time

2.4.2.4 Line Efficiency

PT XY characterizes the line efficiency as the correlation between end hours and

accessible/available hours. The standard time in the estimation is the standard

time in producing 1,000 yields.

(2-10)

(2-11)

(2-12)

(2-13)

2.4.2.5 Smoothness Index

Smoothness index is a scale that demonstrates the degree level of smoothness of

the production line. The smaller the smoothness index the better the run of

production line. Smoothness index can be figured as the equation beneath

(Elsayed, 1985).

2.4.2.6 Balance Delay

Balance delay is a measure of the line inefficiency which comes about because of

idle time because of defective portion of working among station. Balance delay

can be figured as beneath (Elsayed A, 1985).

Where: Ti = time from workstation 1 to i

K = number of workstation

CT = maximum cycle time

CHAPTER III

RESEARCH METHODOLOGY

This Chapter informs the reader how the research was conducted by describing

the detail steps in conducting the research. The steps should be set systematically

to help the researcher solve the initial problems. By constructing the suitable

research methodology, the research and analysis can be done accurately. Hereby

the steps performed to solve the initial problems in this research are on figure 3.1

Initial

Observation

Problem

Identification

Literature Study

Initial Observation

To understand the current condition of efficiency

at PT. XY

To observe and understand the condition of line

M123

To observe the current balancing method

Problem Identification

To identify the effect of having low efficiency

while the efficiency target is high

To define the objective of research

To define the scope, limitations, and assumptions

used in the research

Literature Study

To explain the definition of time study, line

balancing and simulation

To determine the method problem solving

To describe how the method will be used

3.1 Initial Observation

The initial observation is meant as the first step to begin the research. This step is

purposed to deeply know the current condition at PT XY especially the line

efficiency condition and the existing task distribution at each line. It is also

purposed to see how the current method used to balance the line at PT XY. The

problem going to be discussed will be related to those things above as the focus of

this research is to increase the line efficiency of the line having low efficiency.

3.2 Problem Identification

This step is the continuation of initial observation step. In this part, the problem

will be focused to keep the research on the track. The first step of problem

identification is identifying the problem statement. This problem statement will

lead the research to find the answer of the problem. Then, the research objectives,

scope, and assumption must be conducted to keep the research on track and direct

the result to the expected result.

Data Collection

and Analysis

Conclusion and

Recommendation

Data Collection and Analysis

To gather the data for time study

Data tabulation and calculation

To develop the feasible line balancing

To simulate and evaluate the proposed work

station

Conclusion and Recommendation

Inference of the research

Recommendation for the company and

future research

Figure 3. 1 Research Flow

3.3 Literature Study

The literature study is conducted as the learning material in developing the

research. This step will be very important as the way method works and how is it

done are stated in this phase. This will also help to determine what kind of data

should be gathered. It is difficult to develop something without any knowledge as

the basis of research development. Literature study can also be the direction of the

research development.

There are some concern will be discussed through the literature study in this

research. The major concern will be about time study, line balancing, and its

simulation. The time study will include the normal time, allowance, together with

normality test, sufficiency test, and uniformity test. The line balancing will

include the line balancing method together with the measurement of line

balancing.

3.4 Data Collection and Analysis

This step can be divided into two phases. The first the collection of data and then

followed by the analysis of the data collected.

3.4.1 Data Collection

Data of existing method of line balancing problem solving related to Line

M123 Operation Process Chart of Toy DJ123 as the chart will inform how

the assembly process works

The operation method used by the operator at line M123 and it is detailed

with the standard time and the motion for each operation.

Work allowance based on establishment by PT XY

The efficiency target established by PT XY

There are some of collections of data that will be counted by again to support

the analysis of the research:

Time study for each operation using stop watch for some items.

3.4.2 Data Analysis

Creating yamazumi chart based on the line balancing result of current

method

Comparing the cycle time of the operator before and after the

implementation of current balancing method

Calculating the appropriate number of operator based on the calculated

standard time

Evaluate the existing condition through the new standard time that has

been established

3.5 Application of Line Balancing Method

In this step, using the data that has been collected and calculated, the

implementation of balancing method will be done. There are three types of

balancing method will be done in this step. Those three balancing methods are

Largest Candidate Rule (LCR), Killbridge and Wester’s Method (KWM), and

Ranked Positional Weight Method (RPW). Those three methods will result in

their own work station and work arrangement. Then, the best a work arrangement

with the highest efficiency will be chosen.

3.6 Conclusion and Recommendation

Once the data collection and analysis are finished, a conclusion related to the

research must be stated to depict the result of the research as it has been

successfully conducted and telling the reader that the research has been coming to

an end. The conclusion will determine how significance the research was. The

result of the research must determine whether it can answer the research

objectives or not. Since the purpose of the research is only for studying, some

recommendations for the company may be delivered and applied for the benefits

in the future.

Start

Observation

Found a line with

low efficiency?

Literature Study

Root cause

analysis using fish

bone

Record cycle time

Normality Test

Normal Data ?

Uniformity Test

Uniform Data?

Sufficiency Test

Sufficient

Data?

Calculate Normal

Time and Std Time

Apply LCR, KWM,

and RPW method

Compare the

efficiency of those

LB methods

Choose the best

method

Additional action to

make the CT more

balance

Achieve 90%

efficiency?

Compare current

vs proposed work

arrangement

Conclusion and

Recommendation

End

3.7Research Framework

Figure 3. 2 Research Framework

CHAPTER IV

DATA COLLECTION AND ANALYSIS

4.1 Initial Line Efficiency

Firstly, the efficiency of line M123 is measured to know the current efficiency of

the line as the research object. Below is the data recorded for the line efficiency

when the line is running in production schedule. The data is recorded from

October 12 until October 15 2015. By using the equation stated at chapter 2, the

line efficiency of each day’s operation can be calculated as shown in the table

below.

LE = 48.99 %

Table 4.1 Current Line Efficiency

Date Operator

Overtime

Time

(hours)

Output

(in thousand)

Target Line

Efficiency

October 12,

2015 34 102 0.88 1.000 48.99 %

October 13,

2015 34 102 0.914 1.200 61.24 %

October

14,2015 34 102 1.108 1.286 61.69 %

October 15,

2015 34 68 0.923 1.178 56.53 %

Looking at the data above, the average of line efficiency can be calculated.

The line efficiency above is still considered low. It can be seen that it is far from

the company’s target. Logically, using the standard time determined by the

company, to achieve 100% efficiency in producing 1000 units of product per

shift, using the same efficiency calculation, it is supposed to be:

The calculation above shows that it will only need 27 operators to produce 1000

units of product to do it smoothly. In fact, the actual condition shows that it

utilizes up to 34 operators with overtime up to 3 hours for each operator.

4.2 Analyzing Root Cause of Low Efficiency

Low Line

Effieciency

Man

Operator’s time

In each work station

Is not balance

Material

Head is not available

When operator is

About to assembly

MachineMethod

Production output

Is not achieved

Operator can’t

Follow the sequence of

Working like stated

In the guidance

Late head supply

Poor work

arrangement

Different condition

Between guidance

And actual

Inappropriate

Number of operatorHigh cycle time on

Some operators

Std time

Determined is

Not suitable

Figure 4. 1 Fishbone Diagram of Root Cause Analysis

Average 57.11%

1. Man

In terms of man, actually, the number of man assigned to do the final

assembly process of toy DJ123 is already high. But, the target of

production output cannot still be fulfilled. There must be something wrong

with the man assigned to do the final assembly process.

After doing the observation, the skill of people who work for this process

is not equally-likely between one operator and the other operators. Thus,

the standard time in finishing the product between one operator to another

operator may vary. Thus, to overcome this problem, the standard time

determined later should consider the performance rating of each operator

working on each element which is expected to find the most appropriate

number of operator. Finding the most appropriate number is one of the

focus of this research.

2. Machine

In terms of machine, there seems to be no problem since not all operators

utilize machine during the final assembly process. During the observation

time, there is no problem found related to machine operation. So, it can be

concluded that the machine has no problem for this case.

3. Material

In terms of material, some problem is found related to this point. At the

first day of observation, the head part is lately distributed to the production

line. The roto (head) supply from rotocast area is lately distributed to

production line. There was some problem related to supply material to

rotocast area.

4. Method

There are some problems can be described related to method. In doing the

final assembly process of toy DJ123, of course there are some methods

implemented for the process. This method has actually been established by

Industrial Engineering Department. In fact, what actually happen in the

Production line is different with what has been established. This happen

because the target output is different with what has been set. The labor

data sheet appears to show 750 per shift. But, the actual production

process appears to be 1000 units per shift. So, the operators applied some

unstandardized method improvement which is different with what has

been determined by the IE department. The method is also related to the

layout. In this case, the layout is not well arranged. Moreover, some of the

position of operators doing the process is separated. The layout

arrangement is not really good. There is also variance between the actual

time needed in each process and the time stated in the standard. Thus, the

focus will be on finding the most accurate standard time for the work

element.

4.2.1 Observing the Standard Determined by Company

As have been stated before, the real condition of what the production line has been

doing is not the same anymore with what has been plant for the toy DJ123.

Table 4.2 Labor Data Sheet

Code Operator Operations

O-1 1 Date code torso

O-2 Dressing

O-3 Attaching torso to belt

O-4 Assy cape

O-5 2 Cutting polybag

O-6 Grooming hair

O-7 Release rubberband

O-8 3 Hair arrangement

O-9 Hair cutting

O-10 4 Hair setting

O-11 Pegboard extension

O-12 5 Releasing tule

O-13 Trimming

O-14 6 Attach shoes to torso

O-15 Attach to hand

O-16 Tack head to support

Table 4.2 Labor Data Sheet

Code Operator Operations

O-17 7 Fold insert

O-18 Attach to Insert

O-19 8 Lock tab

O-20 Tie down hair

O-21 Lock separator

O-22 9 Dressing torso

O-23 Attach arm

O-24 10 Assembly torso belt

O-25 Attaching to hand

O-26 Join head

O-27 11 Lock toralei support

O-28 Elastic staples

O-29 12 Assembly C

O-30 Elastic staples

O-31 13 Spotweld tab

O-32 Attach to Insert

O-33 14 Touch up

O-34 Put Blister

O-35 15 Locking blister

O-36 Pack to MC

R factor = 34.5 (Takt time based on LDS)

Standard Demand at LDS = 750 units

Hours / shift = 8

Quantity per shift = 750

The table above shows the code name operation of each work element in toy

DJ123. The coding system using O-1, O-2, O-3, and etc is purposed to simplify

the name of each work element in the process of final assembling toy DJ123.

After the breakdown, in total there are 36 operations to complete toy DJ123

assembly process. The actual work arrangement is actually shown at the Labor

Data Sheet. Below is the work arrangement.

Table 4.3 Work Arrangement Based on Labor Data Sheet

Work

Station Operation

Cycle

Time

(s)

Number

of

Operator

CT per

Work

Station

1 O-1 + O-2 + O3 +O4 41.04 1 41.04

2 O-5 + O-6 + O-7 63.18 2 31.59

3 O-8 + O-9 77.94 2 38.97

4 O-10 + O-11 41.4 1 41.4

5 O-12 + O-13 30.84 1 30.84

6 O-14 + O-15 + O-16 40.32 1 40.32

7 O-17 + O-18 31.92 1 31.92

8 O-19 + O-20 + O-21 34.56 1 34.56

9 O-22 + O-23 40.5 1 40.5

10 O-24 + O-25 + O-26 39.36 1 39.36

11 O-27 + 28 37.98 1 37.98

12 O-29 + O-30 39.18 1 39.18

13 O-31 + O-32 38.52 1 38.52

14 O-33 + O-34 34.38 1 34.38

15 O-35 + O-36 39.84 1 39.84

Total Operator 17

Above is the work arrangement proposed by Labor Data Sheet. Based on the

Labor Data Sheet, the total operator needed is only 17. As have been stated

before, Labor Data Sheet is only designed for the 750 demand with 8 working

hours. It means that it can’t cover the actual operation which needs 1000 units to

be produced and in fact, the 8 working hours is not enough.

In any kind of operation, the standard must have been built to accomplish the

target. In running this toy, there is also a standard as the guidance for operator in

producing this toy, the standard itself is Labor Data Sheet (LDS).

The operators usually work based on Labor Data Sheet as it is a document

developed as the guidance of running the toy in Production Schedule. Below is the

data Labor Data Sheet of toy DJ123

Figure 4. 2 Yamazumi of Labor Data Sheet

Looking at the Labor Data Sheet developed for the guidance of operator, it can

clearly be seen that the work is not appropriately distributed. The R-Factor which

is also known as determined takt time is 34.5 s and the other data represent the

time that must be accomplished for each operation.

Looking at the data distribution, it turns out that there are many cycle times below

the determined takt time and there are also many cycle times above the takt time.

It is impossible for example in operation 1, 2,3,4,5 to do the task much longer

than required one. That is why the yamazumi chart itself for the Labor Data Sheet

is not yet balance.

Looking at the Labor Data Sheet again, the quantity per shift set for this toy is 750

toys and is not suitable with the reality when the production line running. This is

why the line leader does not have any guidance when the production running with

the bigger quantity of toy produced. That is why the line leader seems like lost

guidance during the production process.

0

10

20

30

40

50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Cyc

le T

ime

(S)

Work Station

CT per WorkStation

TT

The reason why work distribution is not balance because this Labor Data Sheet is

designed before the toy is mass produced and it is not repaired when the toy is

mass produced. It is why the further time study is needed to make the appropriate

Labor Data Sheet (LDS).

4.2.3 Number of Operator

Evaluation of the number of operator must also be evaluated to determine the

appropriate number of doing overall operation. The number of operator cannot be

over and cannot be less otherwise it can affect the efficiency of the operation. The

formula of determining number of operator has been explained in chapter 2.

N = 21.419 = 22

Based on the Labor Data Sheet, the appropriate number of operator must be 22

operators. It is impossible to have 21.419 operators so it has to be rounded up to

22 operators. 738.98 is the total cycle time needed to run the full operation of toy

DJ123 and 34.5 is the takt time determined by Labor Data Sheet. So, the number

of operator must have been a problem for this toy.

In fact, the LDS only provide 17 operators which are totally insufficient to have

such a standard determined. To gain a good efficiency, the number of operators

must be added 5 people.

4.3 Standard Time at M123

The standard time used must also be analyzed to find the correlation with the low

efficiency that happens at this line. The data designed at the Labor Data Sheet

must be analyzed whether it is math with the actual condition in the production

line. The data from the Labor Data Sheet itself is usually from the pre-determined

time for each operation. In this part, the comparison between the time from Labor

Data Sheet and actual at 555 kaizen will be tried to be analyzed.

Figure 4. 3 Actual time vs LDS time

The graph above is the actual time for each operation vs the Labor Data Sheet.

Based on the graph above, it can clearly be seen that the difference is really big.

That depicts the actual time when production running and the time stated at Labor

Data Sheet. It is obvious that there is a lack of accuracy of the determined

standard time at Labor Data Sheet.

Less accuracy of standard time could result to wrong calculation number of

operator and improper work arrangement. As the effect, the line efficiency

becomes low. Niebel (2003) agree with this statement which state that accurate

standard time can lead to a good efficiency or it can increase efficiency. The bad

thing is if the standard is poorly established, it can increase the cost that must be

spent by the company. The cost may include excessive labor or any kind of waste.

Therefore, the standard time in sewing method should be evaluated. The standard

time should be evaluated by using time study. There are some reasons of using

time study as the tool to evaluate standard time.

1. M123 is ongoing process. Time study can only be done in the process that has

been running. (Niebel, 2003).

0

10

20

30

40

50

60

70

80

90

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Cyc

le T

ime

(s)

Work Station

Actual

LDS

2. Time study is simpler to be done and accurate (Niebel, 2003).

From this analysis, it is found that the poor work arrangement and less accuracy of

standard time have become the root cause of having low line efficiency. Since the

work arrangement is depend on the standard time, increasing the accuracy of

standard time has to be done prior to redesigning the work arrangement. By

having more accurate standard time, it is expected to have adequate number of

operators and proper work arrangement. Thus, time study is discussed first.

4.4 Standard Time before Time Study

The standard time is determined by Industrial Engineering department. The

standard time usually determined during the Production Pilot process. Before that,

preliminary stage is done to determine the pre-determined time. Thus, the

Industrial engineers come up with the standard time determined below.

Table 4. 2 Standard time before time study

Operations Code Time STD

Date code torso O-1 6 12.250

Dressing O-2 13.62

Attaching torso to belt O-3 8.94

Assy cape O-4 12.48

Cutting polybag O-5 6.9 24.500

Grooming hair O-6 34.02

Release rubberband O-7 22.26

Hair arrangement O-8 33.66 24.500

Hair cutting O-9 44.28

Hair setting O-10 38.4 12.250

Pegboard extension O-11 3

Releasing tule O-12 5.76 12.250

Trimming O-13 25.08

The table above is the standard time obtained from the Operation Process Chart

(OPC). By having Operation Process Chart, the process is expected to be seen

clearly. The Operation Process Chart (OPC) is shown at appendix 1.

Attach shoes to torso O-14 8.16 12.250

Attach to hand O-15 24.78

Tack head to support O-16 7.38

Fold insert O-17 15.12 12.250

Attach to Insert O-18 16.8

Lock tab O-19 5.28

12.250 Tie down hair O-20 24

Lock separator O-21 5.28

Table 4.2 Standard time before time study (continued)

Dressing torso O-22 20.88 12.250

Attach arm O-23 19.62

Assembly torso belt O-24 15.24

12.250 Attaching to hand O-25 18.42

Join head O-26 5.7

Lock toralei support O-27 10.86 12.250

Elastic staples O-28 27.12

Assembly C O-29 10.68 12.250

Elastic staples O-30 28.5

Spotweld tab O-31 12.06 12.250

Attach to Insert O-32 26.46

Touch up O-33 23.88 12.250

Put Blister O-34 10.5

Locking blister O-35 29.04 12.250

Pack to MC O-36 10.8

Total Standard Hours 630.9 208.248

4.5 Actual Standard Time

4.5.1 Normality Test

The normality test is done using minitab 17. In normality time, the thing that is

concerned most is the P-Value. The time study result is inputted to the minitab

application and the minitab 17 will automatically do the analysis. The result will

directly be shown. For this final project, the level of significance for the data is

0.05. So, if it is found that the P-Value of time study for each work element bigger

than 0.05, “fail to reject H0” is the conclusion. However, if the P-Value is lower

than 0.05, the conclusion must be “reject H0 or “accept HA”.

For example looking at the operation 1 (O-1), the P-Value is shown to be 0.836. It

means the P-Value is greater than 0.05, then the conclusion is “fail to reject H0”.

So the data can said normally distributed. Some of the data may not pass the

normal distribution test at the beginning, so the data must be collected again until

the P-Value result shown by minitab 17 becomes greater than 0.05. For example,

the data at Operation 3 (O-3) firstly showed 0.013 as the P-Value. Thus, the

conclusion must be “reject H0” which mean the data collected for O-3 is not

normally distributed. So, stop watch time study must be conducted again for O-3

until the P-Value become greater than 0.05. The attached Normality data test is

already been completed and all the data shown in the appendix is already normally

distributed for all operation.

4.5.2 Uniformity Test

A set of data may be considered normally distributed, but it is not going to be

good with wide variance. Thus, after dealing with normality test, the next step

should be uniformity test. In uniformity test, upper and lower limit must be

determined to figure out whether the data uniform or not. The formula has been

stated at chapter 2. To determine the upper and lower limit, the standard deviation

must firstly be found. Then, to achieve 99% area normal distribution, six sigma

theorems is used by using three times of standard deviation for upper and lower

limit from the mean of the data. That is the way to determine the upper and lower

limit of the data.

In this case, taken one example of operation 1 (O-1), standard deviation of the

data is 0.87 with the mean of 10.42. So, the Upper Control Limit (UCL), and the

Lower Control Limit (LCL) can be calculated as below:

s

After determining the Upper Control Limit (UCL) and Lower Control Limit

(LCL) of the data of operation 1 (O-1), next is looking at the data for O-1 whether

there is some data exceed the Upper Control Limit or below the Lower Control

Limit. For simplifying the checking process, the maximum value of data and the

minimum value of the data must be shown. If the maximum data exceeds the

Upper Control Limit, then the data must be removed. Otherwise, if the minimum

data lower than Lower Control Limit (LCL), then the data must also be removed.

For the O-1, the maximum value is 11.55 s and the lowest value is 8.77 s. So, both

of the data is still in control limit. So the data is considered uniform. The rest of

uniformity of all operations can be seen at the appendix.

4.5.3 Sufficiency Test

The purpose of this test is to figure out whether the number of the data collected

has been sufficient or not. The formula for sufficiency test is stated at chapter 2.

The result sufficiency test for all operations is shown at the appendix. The

example of calculating the sufficiency test is shown below;

(

√

∑

)

( √

)

Based on the result of sufficiency test, the number of observation that must be

done for operation 1 (O-1) is 10. In fact, the data taken for operation 1 (O-1) is 11.

So, it is considered that the data is enough and pass the sufficiency test.

4.5.4 Performance Rating

It is known that the performance rating is one of the factors to get the normal time.

Performance rating can vary from one operator to other operators. The evaluation

of performance rating can be very useful to determine normal time. Niebel (2003)

mentioned four factors in evaluating the performance of the operator; skill, effort,

condition, and consistency. It assumed that all the operators who become the

object of time study are considered to have the same average condition and valued

as D with 0.00 point. So, only skills, effort, and consistency are evaluated. Those

are evaluated the line leader. The table below is the example of performance

rating calculation for the operator who is responsible for O-1

Table 4. 3 Performance of Operator 1

Skill C2 0.03

Effort C2 0.02

Condition D 0

Consistency C 0.01

Algebraic Sum 0.06

Performance Factor

1.06

Toy DJ123 is one of the toys with the most complicated process. It is found that

no operator has the performance rating below 1 which mean the operator observed

for time study do the process within or below the normal time. For more detail, it

can be seen at the appendix 4.

4.5.5 Normal Time

After dealing with all the evaluations above starting from normality test,

uniformity test, sufficiency test, until the performance rating, the next step is

determining the normal time for each operations. All the evaluations above will be

used to determine the normal time. Normal time itself is obtained by multiplying

mean time with performance rating of the operators as defined in equation. The

data shows that more skillful and consistent the operator, the bigger the effort, the

bigger the normal time will be. Calculation of normal time is done like below;

Above is the example of calculating standard time. The average of operation 1 (O-

1) is 10.43 and the performance rating of operator observed assessed by the line

leader is 1.06. Thus, the normal time is the multiplication of average and

performance rating with the result of 11.06 s.

4.5.6 PFD (Personal, Fatigue, and Delay)

For the personal matter, fatigue and delay, PT XY has already had its own study

to determine this allowance. The allowance is determined for each area including

the final assembly area. The allowance is 11.2 %. This allowance covers personal,

fatigue, and delay allowance.

4.5.7 Standard Time

Standard time is obtained after finding the allowance because in the real life, no

operators can do the task 8 hours full without any delay or getting distracted. The

way to calculate the standard time has been stated on chapter 2. Using the

equation, the standard time can be calculated as below;

Table 4. 4 Actual Standard Time

Code Process Second per

unit

O-1 Date code torso 12.30

O-2 Dressing 29.04

O-3 Attaching torso to belt 17.99

O-4 Assy cape 25.39

O-5 Cutting polybag 5.41

O-6 Grooming hair 29.28

O-7 Release rubberband 18.81

O-8 Hair arrangement 33.80

O-9 Hair cutting 44.46

O-10 Hair setting 76.56

O-11 Pegboard extension 6.00

O-12 Releasing tule 5.73

O-13 Trimming 25.28

O-14 Attach shoes to torso 12.48

O-15 Attach to hand 37.45

O-16 Tack head to support 11.51

O-17 Fold insert 13.89

O-18 Attach to Insert 16.04

O-19 Lock tab 5.00

O-20 Tie down hair 21.42

Table 4.4 Actual Standard Time (continued)

Code Process Second per

unit

O-21 Lock separator 4.88

O-22 Dressing torso 29.78

O-23 Attach arm 27.24

O-24 Assembly torso belt 15.25

O-25 Attaching to hand 18.41

O-26 Join head 5.56

O-27 Lock toralei support 8.45

O-28 Elastic staples 21.08

O-29 Assembly C 8.61

O-30 Elastic staples 23.44

O-31 Spotweld tab 9.04

O-32 Attach to Insert 20.19

O-33 Touch up 36.35

O-34 Put Blister 15.25

O-35 Locking blister 28.71

O-36 Pack to MC 10.44

Total time 730.50

Based on the table above, the new standard time has been obtained for every work

element. It can be seen that the standard time per unit has been increased from

630.9 s to 730.50 s. It means that the difference between the actual time and

standard time obtained by time study is different.

4.6 Line Balancing

The next step must be one of the most important parts of this research. The next

step is about line balancing method application. To ensure the result and

providing several solutions, the line balancing analysis will be done through 3

different method application; they are Largest Candidate Rule (LCR), Killbridge

and Wester Method (KWM), and Ranked Positional Weigh (RPW).

Since there is no certain standard for how many available times allowed in a day,

thus the takt time for the line balancing process is considered as below:

It is considered the assumed that the allowed over time is 2 hours because among

the 4 days operation, the lowest overtime is 2 hours. The toy is designed to run for

750 toys per shift but in fact, the number of toy that must be produced is 1000

units. Looking at that fact, the takt time used is considered to be the same as the

actual operation.

4.6.1 Largest Candidate Rule

Largest candidate rule is started by using the precedence table consists of

predecessor and successor. The precedence diagram contains information about

the sequence of process in final assembly process of toy DJ1123. The precedence

diagram will also be used in the other method as the basic information of the final

assembly process. For more detail, the information of precedence diagram is

shown below

5

6

22

1

8

9

31

7 17 18 19 20 21

23 24 25 26

2 3 4 14 15 16 27

10 11 12 13 28 29 30 33 34 35

32

36


46

Table 4. 5 Precedence Table

No Operation Te Immediate Predecessor

1 O-5 5.41 -

2 O-6 29.28 -

3 O-22 29.78 -

4 O-1 12.30 -

5 O-8 33.80 -

6 O-9 44.46 -

7 O-31 9.04 -

8 O-7 18.81 O-5 O-,6

9 O-23 27.24 O-22

10 O-2 29.04 O-1

11 O-10 76.56 O-8, O-9

12 O-32 20.19 O-31

13 O-17 13.89 O-5, O-6, O-7

14 O-3 17.99 O-1, O-2

15 O-11 6.00 O-8, O-9, O-10

16 O-18 16.04 O-5, O-6, O-7, O-17

17 O-4 25.39 O-1, O-2, O-3

18 O-12 5.73 O-8, O-9, O-10, O-11

19 O-19 5.00 O-5, O-6, O-7, O-17, O-18

20 O- 13 25.28 O-8, O-9, O-10, O-11, O-12

21 O-20 21.42 O-5, O-6, O-7, O-17, O-18, O-19

22 O-14 12.48 O-1, O-2, O-3, O-4, O-8, O-9, O-10, O-11, O-12, O-13

23 O-21 4.88 O-5, O-6, O-7, O-17, O-18, O-19, O-20

24 O-15 37.45 O-1, O-2, O-3, O-4, O- 8, O-9, O-10, O-11, O-12, O-13, O-14

25 O-24 15.25 O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23

26 O-16 11.51 O-1, O-2, O-3, O-4, O-8, O-9, O-10, O-11, O-12, O-13, O-14,

O-15

27 O-25 18.41 O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24

28 26 5.56 O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24, O-25

29 27 8.45

O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24, O-25, O-26, O-1, O-2, O-3, O-4, O-8, O-9, O-10 O-, O-

11, O-12, O-13, O-14, O-15,O-16

30 28 21.08

O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24, O-25, O-26, O-1, O-2, O-3, O-4, O-8, O-9, O-10 O-, O-

11, O-12, O-13, O-14, O-15,O-16,O-27,O-31,O-32

31 29 8.61

O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24, O-25, O-26, O-1, O-2, O-3, O-4, O-8, O-9, O-10 O-, O-

11, O-12, O-13, O-14, O-15,O-16,O-27,O-31,O-32,O-28

32 30 23.44

O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24, O-25, O-26, O-1, O-2, O-3, O-4, O-8, O-9, O-10 O-, O-

11, O-12, O-13, O-14, O-15,O-16,O-27,O-31,O-32,O-28,O-

29

33

33 36.35

O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24, O-25, O-26, O-1, O-2, O-3, O-4, O-8, O-9, O-10 O-, O-

11, O-12, O-13, O-14, O-15,O-16,O-27,O-31,O-32,O-28,O-

29,O-30

Table 4. 6 Precedence Table (continued)

No Operation Te Immediate Predecessor

34 34 15.25

O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24, O-25, O-26, O-1, O-2, O-3, O-4, O-8, O-9, O-10 O-, O-

11, O-12, O-13, O-14, O-15,O-16,O-27,O-31,O-32,O-28,O-

29,O-30,O-33

35 35 28.71

O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24, O-25, O-26, O-1, O-2, O-3, O-4, O-8, O-9, O-10 O-, O-

11, O-12, O-13, O-14, O-15,O-16,O-27,O-31,O-32,O-28,O-

29,O-30,O-33,O-34

36 36 10.44

O-5, O-6, O-7, O-17, O-18, O-19, O-20, O-21, O-22, O-23,

O-24, O-25, O-26, O-1, O-2, O-3, O-4, O-8, O-9, O-10 O-, O-

11, O-12, O-13, O-14, O-15,O-16,O-27,O-31,O-32,O-28,O-

29,O-30,O-33,O-34, O-35

The work element column describes the number element of working and the cycle

time is put in the column next to it. In the immediate predecessor column, it

describes all the predecessors needed before the work element can be started.

Table 4. 7 Proposed Work Station

Work

Station CT

# of

Operator

CT of

WS

1 34.69 1 34.69

2 29.78 1 29.78

3 31.11 1 31.11

4 33.8 1 33.8

5 44.6 2 22.3

6 36.28 1 36.28

7 29.04 1 29.04

8 76.56 3 25.52

9 34.08 1 34.08

10 34.03 1 34.03

11 31.39 1 31.39

12 36.01 1 36.01

13 33.9 1 33.9

14 20.13 1 20.13

15 37.45 1 37.45

16 35.48 1 35.48

17 29.53 1 29.53

18 32.05 1 32.05

19 36.35 1 36.35

20 25.69 1 25.69

21 28.71 1 28.71

Number of operator 24

Above is the table for proposed work station using the proposed work station, the

total work station needed for all the final assembly process is 24 work stations.

The work stations are arranged using the Largest candidate Rule method and is

applied through the cycle time arranged and is not exceeding the Takt time for

each work stations. It is also done by considering the precedence diagram to

ensure that each station can be properly arranged and the process can be flown

and properly put in order. The time allocated for each work station can be seen as

below;

Figure 4. 5 Yamazumi Chart of LCR Method Application

It can be seen from the chart that the cycle time of each operation has almost all

lay down below the takt time. But there is one problem when two of the operation

still exceeds the takt time as the process is known to have a long cycle time. The

other solution to balance the and reduce the cycle time is by separating the process

or moving some process with high cycle time to the work station with the lowest

cycle time. It is actually kind of practical since the theory only by using

precedence diagram will not be enough to determine which process can be moved

or reduced. The more consultation and trial with the field executor must be done.

But, before doing so, let’s first compare the line balancing result between three

methods.

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 101112131415161718192021

Cyc

le T

ime

(s)

Work Station

CT of WS

TT

5,6

22

1,7

8

9

31,23

2 9

10

32,17

3,18

11,4 10

10 12,19,13

20,14

21,24

15

16,25,26

27,28

29,30

33 34,36

35

Figure 4. 6 Proposed Layout of Largest Candidate Rule

50

4.6.1.1 Evaluation of Largest Candidate Rule

To ensure the performance of the line arrangement proposed, the result of

arrangement must also be evaluated by calculating the smoothness index and the

balance delay of the line arrangement proposed.

Table 4. 8 Evaluation of LCR

Operator CT (CTi-CT max)2

1 34.69 7.6176

2 29.78 58.8289

3 31.11 40.1956

4 33.8 13.3225

5 22.3 229.5225

6 22.3 229.5225

7 36.28 1.3689

8 29.04 70.7281

9 25.52 142.3249

10 25.52 142.3249

11 25.52 142.3249

12 34.08 11.3569

13 34.03 11.6964

14 31.39 36.7236

15 36.01 2.0736

16 33.9 12.6025

17 20.13 299.9824

18 37.45 0

19 35.48 3.8809

20 29.53 62.7264

21 32.05 29.16

22 36.35 1.21

23 25.69 138.2976

24 28.71 76.3876

Total 730.66 1764.18

√

Based on the smoothness calculation, it is obtained that the result of smoothness

index is 42.002. Theoretically, the lower the smoothness index the better it is. To

obtain the smoothness index, each cycle time in each work station must be

subtracted by the highest cycle time in all operations then square the result.

Station 1

Balance Delay

After dealing with the smoothness index, the next is calculating the balance delay.

Using the Largest Candidate Rule method, the balance delay found is to be

18.71% which result only 81.29% of line efficiency. The balance delay is

calculated using the formula above.

4.6.2 Killbridge and Wester Method

Figure 4. 7 Killbridge and Wester Method

53

Table 4. 9 Killbridge and Wester Method

Work

Station Operation CT

CT per work

station

Number of

Operator

1 O-5 5.41

34.70 1 O-6 29.28

2 O-7 18.81

32.70 1 O-17 13.89

3 O-22 29.78 29.78 1

4 O-23 27.24 27.24 1

5 O-1 12.30 12.30 1

6 O-2 29.04

35.03 1 O-11 6.00

7 O-8 33.80 33.80 1

8 O-9 44.46 22.23 2

9 O-10 76.56 25.5 3

10 O-31 9.04

29.24 1 O-32 20.19

11 O-3 17.99

34.03 1 O-18 16.04

12 O-4 25.39

31.12 1 O-12 5.73

13 O-13 25.28

30.27 1 O-19 5.00

14 O-14 12.48

33.90 1 O-20 21.42

15 O-21 4.88

20.13 1 O-24 15.25

16 O-15 37.45 37.45 1

17

O-16 11.51

35.48 1 O-25 18.41

O-26 5.56

18 O-27 8.45

29.53 1 O-28 21.08

19 O-29 8.61

32.05 1 O-30 23.44

20 O-33 36.35 36.35 1

21 O-34 15.25 15.25 1

22 O-35 28.71 28.71 1

23 O-36 10.44 10.44 1

Total Operators needed 26

Above is the work arrangement table using Kilbridge and Wester’s Method

(KWM). By applying this method, the total numbers of operators needed are 24

people with 24 work station. The KWM method is utilized using the precedence

diagram.

Figure 4. 8 Yamazumi Chart of KWM

The figure above is the yamazumi chart shown by using Killbridge and Wester

Method. The yamazumi chart shows that the work is not really properly

distributed since there are many work station with low cycle time and there are

also many station with the work station near the takt time. The result of this

method does not show a really good work arrangement although almost all the

work station having cycle time below the takt time with fewer number of

operators needed in comparison with the initial work arrangement. For the

evaluation of Killbridge and Wester method, the calculation is done in the

following section.

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

1 3 5 7 9 11 13 15 17 19 21 23

Cyc

el T

ime

(s)

Work Station

CT of WS

TT

4.6.2.1 Evaluation of KWM




Table 4. 10 Evaluation of KWM

WS CT CT max – CT i (CT Max-CT i)2

1 34.70 2.75 7.57

2 32.70 4.75 22.58

3 29.78 7.67 58.83

4 27.24 10.21 104.29

5 12.30 25.15 632.77

6 35.03 2.42 5.83

7 33.80 3.65 13.34

8 22.23 15.22 231.64

9 22.23 15.22 231.64

10 25.52 11.93 142.36

11 25.52 11.93 142.36

12 25.52 11.93 142.36

13 29.24 8.21 67.47

14 34.03 3.42 11.70

15 31.12 6.33 40.13

16 30.27 7.18 51.52

17 33.90 3.55 12.62

18 20.13 17.32 299.90

19 37.45 0.00 0.00

20 35.48 1.97 3.87

21 29.53 7.92 62.73

22 32.05 5.40 29.19

23 36.35 1.10 1.21

24 15.25 22.20 492.96

25 28.71 8.74 76.33

26 10.44 27.01 729.45

Total 3614.63

√

The table shows the calculation of smoothness index for the proposed work

arrangement arranged by Killbridge and Wester Method. The smoothness index

obtained is not significantly good since the number obtained is 60.12. For the

smoothness index calculation, the lower the smoothness index, the better it will

be.

Balance Delay

The calculation of balance delay is done to get the clear picture of the delay of the

process can be. Through the application of Killbridge and Wester Method, the

balance delay is obtained to be 25% which is not very good and cannot fulfill the

efficiency target determined by the company. The balance delay calculation can

be obtained through the application of formula stated on chapter 2.

By obtaining the balance delay, the efficiency of the line can roughly be obtained

by looking of the percentage remaining. Looking at the calculation above, the line

efficiency can be said to be 75% since the balance delay obtained through

Killbridge and Westers Method is 25%.

4.6.3 Rank Positional Weight

To calculate the Rank Position weight, calculating the weight is a must to be done.

Below is the example of how to calculate the positional weight:

O-1 + O-2 + O-3 + O-4 + O-14 + O-15 + O-16 + O-27 + O-28 + O-29 + O-30

+ O-33 + O-34 + O-35 + O-36

12.30 + 29.04 + 17.99 + 25.39 + 12.48 + 37.45 + 11.51 + 8.45 + 21.08 + 8.61 +

23.44 + 36.35 + 15.25 + 28.71 + 10.44 = 298.74

Based on the calculation, it can be seen that the weight for operation 1 (O-1) is

298.74. The detail RPW matrix is given on appendix 9.

Table 4. 11 Work Station of RPW Application

No Operation Cycle Time Number of

Operator

Cycle time per

workstation

1 O-9 44.46 2 22.23

2 O-8 33.8 1 33.8

3 O-10 76.56 3 25.52

4 O-6 29.28 1 29.28

5 O-1 12.3

1

31.11 O-7 18.81

6 O-2 29.04

1

34.45 O-5 5.41

7 O-3 17.99

1

31.888 O-17 13.898

8 O-11 6

1

35.78 O-22 29.78

9 O-12 5.73

1

31.12 O-4 25.39

10 O-13 25.28

1

30.28 O-19 5

11 O-18 16.04

1

28.52 O-14 12.48

12 O-23 27.24

1

32.12 O-21 4.88

13 O-20 21.42

1

36.67 O-24 15.25

14 O-15 37.45 1 37.45

15

O-25 18.41

1

33.01

O-31 9.04

O-26 5.56

16 O-32 20.19

1

31.7 O-16 11.51

17 O-27 8.45

1

29.53 O-28 21.08

18 O-29 8.61

1

32.05 O-30 23.44

19 O-33 36.35 1 36.35

20 O-34 15.25

1

25.69 O-36 10.44

21 O-35 28.71 1 28.71

Total number of operator 24

Based on the calculation table of implementation of Rank Positional Weight, the

total work station that can be applied is 21 work stations with 23 operators

utilized. The work arrangement of Rank Positional Weight implementation is

done by calculating the weight of each operation as attached in the attachement.

Figure 4. 9 Yamazumi Chart of RPW method application

Above is the result of Ranked Positional Weight line balancing method. Looking

at the yamazumi chart, there are two processes actually exceeds the takt time since

the process needs long time to be done. The work distribution between one

operators and other operator is not yet evenly distributed. Thus, the direct

practical application can be done to improve the work station arranged by RPW

application. Using the RPW work arrangement as the foundation, the work

element can be moved or separated to most balance process.

To know the performance of the line after being arranged through the application

of Rank Positional Weight method, the evaluation of this method can be done as

being done in the following calculation.

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Cyc

le T

ime

(s)

Work Station

CT

TT

4.6.3.1 Evaluation of RPW




Smoothness Index

Table 4. 12 Smoothness Index of RPW

Operator CT (CT-CT

max)2

1 22.23 231.65

2 22.23 231.65

3 33.80 13.32

4 25.52 142.32

5 25.52 142.32

6 25.52 142.32

7 29.28 66.75

8 31.11 40.20

9 34.45 9.00

10 31.89 30.94

11 35.78 2.79

12 31.12 40.07

13 30.28 51.41

14 28.52 79.74

15 32.12 28.41

16 36.67 0.61

17 37.45 0.00

18 33.01 19.71

19 31.70 33.06

20 29.53 62.73

21 32.05 29.16

22 36.35 1.21

23 25.69 138.30

24 28.71 76.39

Total 1614.06

√

Looking at the table above analyzing the smoothness index obtained through the

RPW application, it can be seen that the smoothness index is to be 40.17. The

formula used to calculate the Smoothness Index is already stated on chapter 2.

The result of smoothness index does not appear to be so good but in comparison

with the other 2 methods, it appears to be the lowest smoothness index and can be

considered as the best method among the other two methods.

Balance Delay

%

Above is the balance delay result of the Rank Positional Weight method

application. The balance delay calculation is done through the implementation of

formula stated on chapter 2. The balance delay result appears to be 18.27%. The

result is quite good in comparison with the other two methods. This application

appears to show the lowest balance delay which means having the highest

efficiency among those two other methods. The efficiency of the line through the

application of RPW method is 81.29%. This is actually still below the standard of

PT.XY.

9

9

8

10 10

10 6

1,7

2,5

3,17

11,22

12,4

13,19

18,14

23,21

24,20

15

25,31,26

32,16

27,28

29,30

33

34,36

35

Conveyor

Figure 4. 10 Proposed Layout of Rank Position Weight

62

4.7 Comparison of Three Methods

After dealing with three methods to analyze the best result of line balancing, the

next thing is to compare all the result in terms of balance delay, efficiency, and

smoothness index

4.7.1 Balance Delay

Figure 4. 11 Balance Delay Comparison

Based on the table above, it is clear that the KWM method appears to be the

method with highest delay, thus the KWM is the worst in terms of Balance Delay.

Meanwhile, LCR and RPW method appears to show the best method in terms of

the delay. The LCR is still the lowest with a really slight different between these

two methods in terms of balance delay.

Figure 4. 12 Efficiency Comparison

0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

LCR KWM RPW

Pe

rce

nta

ge

Method

Balance Delay

Balance Delay

70.00%

72.00%

74.00%

76.00%

78.00%

80.00%

82.00%

LCR KWM RPW

Pe

rce

nta

ge

Method

Effieciency

Effieciency

Utilizing three different methods, the efficiency of those three methods have been

obtained. Looking at the efficiency result, the KWM again shows the lowest

efficiency. It all makes sense since the highest delay is at the KWM method. The

LCR and RPW method shows the same level of efficiency since this method have

low balance delay.

Figure 4. 13 Smoothness Index Comparison

The figure above shows the smoothness index comparison for Largest Candidate

Rule, Killbridge and Wester, and Rank Positional Weight Method. KWM again

shows the highest smoothness index while in this case, the lower smoothness

index, the better it is. LCR and RPW method again shows a slight different for

smoothness index. Using RPW method, the smoothness index appears to be the

best among those three methods as it shows the lowest value of smoothness index.

Looking at those three methods that have been applied; Largest Candidate Rule,

Killbridge and Wester Method, and Rank Position Weight, it is clear that the best

method to be applied is Rank Position Weight since it has the lowest balance

delay (can be considered the same with LCR) and also the lowest smoothness

index.

0

20

40

60

80

LCR KWM RPW

Smo

oth

ne

ss In

de

x P

oin

t

Method

Smoothness Index

Smoothness Index

4.8 Additional Action

The result of line balancing methods application do not really show a very good

yamazumi chart since some of the cycle time are still high. Thus, the additional

action is needed to reduce the cycle time in operation with high cycle time.

Figure 4. 14 Chosen Yamazumi Chart of RPW Application

Although it is found that the best method to be applied is Rank Positional Weight,

the room for improvement is still available there. It can be seen that some of the

cycle time is exceeding the takt time determined although it does not exceed

much. Let’s take a look at one example at operation 15 at workstation 17. The takt

cycle time at that work station is 37.45s meanwhile the takt time is 36. Not only

at work station 17, cycle time exceeding the takt time also happen at work station

16 and 22. Both do the operation 24 and 34,36. The next is focusing on reducing

cycle time at those both work stations.

1. Reducing Cycle time at operation 15 (Work Station 17)

Labor Data Sheet state that operation 15 is about attaching part to doll

together with the join head process. Here, looking at the precedence diagram

and the actual process, the join head process does not have to be done at work

station 17. It can be moved to next process at work station 20 with the cycle

time.

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 101112131415161718192021222324

Series1

Series2

There is an operation of attaching head to torso. Consulting with the IE

department, it can be moved to operation 14 at work station 14. At that work

station, the cycle time is still 28.52.

The time study is done to reduce the cycle time at work station 17. Below is

the CT of attaching head only.

Table 4. 13 Cycle time of attaching head

No CT

1 4.45

2 3.92

3 4.01

4 4.05

5 4.2

6 3.97

7 4.05

avg 4.09

Std dev 0.18

P Value 0.103

Min 3.92

Max 4.45

UCL 4.99

LCL 3.38

N’ 6.80

Based on the table, it can be concluded that the cycle time for head only 4.09.

Next is moving this operation to work station 14. After moving this operation,

the new time for this operation for work station 14 must be determined. Thus,

the time study must again be applied to determine the new time for this work

station. Below is the new time study result for work station 14.

Table 4. 14 New cycle time of work station 14

No CT

1 29.97

2 30.03

3 30.56

4 29.81

5 31.03

6 30.34

7 30.36

8 29.87

No CT

9 30.41

10 31.21

avg 27.64

Std dev 0.47

P Value 0.361

Min 29.81

Max 31.21

UCL 32.63

LCL 28.39

N' 5.76

NT 29.30

Allowance 0.11

ST 32.58

The data above shows the new time needed for work station 14. After moving the

join head process, the cycle time at work station 14 increase to become 32.58 s.

The addition of work load to operator can surely increase the time needed for

completion of process.

Increasing cycle time at work station 14 meaning reducing the cycle time at

operation 17 since one work load has been moved to work station 14. Below is the

new cycle time of operation 17:

Table 4. 15 New cycle time for work station 17

No CT

1 26.46

2 27.04

3 27.04

4 28.31

5 27.61

6 27.31

7 27.43

8 28.09

9 27.21

10 27.41

avg 27.39

Std dev 0.53

P Value 0.281

Min 26.46

Max 28.31

UCL 29.90

LCL 24.87

N' 9.51

NT 29.58

Allowance 0.11

ST 32.90

Above is the cycle time of operation 17. It is clear that the cycle time has

successfully been reduced. The standard time is now become 32.90 seconds.

2. Adding Supporting Jig at Work Station 16

It can be seen that the current cycle time after the RPW method

implementation at work station 16 is still high. The processes itself are

assembly torso and tie down process. To reduce the cycle time at this work

station, additional jig is installed to ease the torso assembly process. Below is

the cycle time at works station 16 after installing the jig itself.


No CT

1 27.075

2 28.12

3 27.15

4 27.15

5 28.09

6 27.32

7 27.41

8 28.21

9 26.97

10 27.03

avg 27.45

Std dev 0.49

P Value 0.872

Min 26.97

Max 28.21

UCL 29.69

LCL 25.49

N’ 9.26

NT 29.65

Allowance 0.11

ST 32.97

The cycle time at work station 16 has been reduced to become 32.97 since the jig

installment has made the operator easier during the assembly process since the

operator does not need to hold the torso by their hand anymore.

3. Replacing the Comb at Work Station 22 and 3

The operation at work station 22 is 33 which include trimming hair process. The

trimming process uses comb intently to do the doll hair treatment. Currently, the

comb used by the operator is rough and is not smooth when trimming process

using hair. Then, the new comb is given which is more smooth and leaner to make

the trimming process faster.


No CT

1 26.125

2 27.02

3 25.05

4 26.12

5 25.98

6 26.54

7 25.63

8 26.42

9 26.01

10 25.42

avg 26.03

Std dev 0.57

P Value 0.890

Min 25.05

Max 27.02

UCL 28.72

LCL 23.35

N' 9.26

NT 28.11

Allowance 0.11

ST 31.26

Table above is the data of trimming process after changing with the new comb

with leaner design. It is way faster than before and it can be seen that the new

cycle time has been reduced to become 31.26 s.

Similar with work station 22, work station 3 also use comb as the tool. Although

the initial cycle time does not exceed the takt time, reducing the cycle time in this

work station can make the work distribution between each operator more balance.

Below is the new cycle time at work station 3.


No CT

1 25.02

2 26.08

3 24.32

4 26.04

5 26.1

6 25.17

7 24.13

8 25.18

9 24.23

10 25.31

avg 25.16

Std dev 0.76

P Value 0.220

Min 24.13

Max 26.1

UCL 28.38

LCL 21.85

N’ 9.26

NT 26.42

Allowance 0.11

ST 29.37

It can be seen that now the standard time at work station 3 is 29.37. It can be

concluded that the new comb utilization is very helpful in making the hair-related

operation easier.

4. Reducing Cycle Time at Work Station11

Based on RPW calculation, there are two operations at work station 11; there are

operation 11 and 22. To make it more balance, the operation 11 is combined with

other operation 10 in work station 4 (actually needs three operators for this

process). Thus, because the operation is moved to work station 4 which needs

three operators, the cycle time at the work station become as shown in the table

below.


No CT

1 68.72

2 68.7

3 68.98

4 69.04

5 68.14

6 69.89

7 67.11

8 69.12

9 68.51

10 69.56

avg 68.78

Std dev 0.77

P Value 0.310

Min 67.11

Max 69.89

UCL 72.20

LCL 64.80

N' 9.26

NT 74.28

Allowance 0.11

ST 82.60

CT per Ops 27.53

Above is the new cycle time for work station 4.It has been increased since the

cycle time at work station 11 is reduced. The cycle time at Work station 11 only

left O-22 alone which is 29.78 s.

5. Reducing Cycle Time at Work station 9

Work station 9 consists of operation of cutting finish and dressing polybag. In this

operation, dressing method is introduced. Usually, the dressing is done after the

shoes are attached so the dress often sticks to the shoes. Now, the dressing process

first then the attaching shoes will be done later.


No CT

1 24.55

2 25.21

3 24.03

4 24.21

5 25.43

6 23.98

7 24.55

8 25.24

9 23.94

10 24.45

avg 24.56

Std dev 0.56

P Value 0.175

Min 23.94

Max 25.43

UCL 27.10

LCL 22.27

N' 9.26

NT 26.52

Allowance 0.11

ST 29.49

Above is the cycle time at work station 9 after applying the new dressing method

and it is clear that the cycle time at work station can be reduced.

The cycle time in some work station have been improved and expected to lead to

the better result of efficiency. In conclusion, the new arrangement and the time

can be shown in the following table.

Table 4. 21 New cycle time for each work station

No Operation CT

Number of

Operator

CT of

Work

Station

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 101112131415161718192021

Cyc

le T

ime

(s)

Work Station

CT of Work Station

TT

1 O-9 44.46 2 22.23

2 O-8 29.37 1 29.37

3 O-10,O-11 82.59 3 27.53

4 O-6 29.28 1 29.28

5 O-1, O-7 31.11 1 31.11

6 O-2, O-5 29.49 1 29.49

7 O-3, O-17 31.888 1 31.888

8 O-22 29.78 1 29.78

9 O-12, O-4 31.12 1 31.12

10 O-13, O-19 30.28 1 30.28

11 O-18, O-14 32.58 1 32.58

12 O-23, O-21 32.12 1 32.12

13 O-24, O-20 32.97 1 32.97

14 O-15 32.9 1 32.9

15 O-25, O-31, O-26 33.01 1 33.01

16 O-32, O-16 31.7 1 31.7

17 O-27, O-28 29.53 1 29.53

18 O-29, O-30 32.05 1 32.05

19 O-33 31.26 1 31.26

20 O-34, O-36 25.69 1 25.69

21 O-35 28.71 1 28.71

Figure 4. 15 Improved Yamazumi Chart

4.9 Final Evaluation

As the additional action has been done to make the production process smoother,

then the final evaluation must be done to see the result obtained on terms of

Efficiency, balance delay, and smoothness index

Table 4. 22 Evaluation of Final Work Arrangement

No CT CT

Max-i

(CT

Max-i)2

1 22.23 10.8 116.21

2 22.23 10.8 116.21

3 29.37 3.6 13.25

4 27.51 5.5 30.25

5 27.51 5.5 30.25

6 27.51 5.5 30.25

7 29.28 3.7 13.91

8 31.11 1.9 3.61

9 29.49 3.5 12.39

10 31.888 1.1 1.26

11 29.78 3.2 10.43

12 31.12 1.9 3.57

13 30.28 2.7 7.45

14 32.58 0.4 0.18

15 32.12 0.9 0.79

16 32.97 0.0 0.00

17 32.9 0.1 0.01

18 33.01 0.0 0.00

19 31.7 1.3 1.72

20 29.53 3.5 12.11

21 32.05 1.0 0.92

22 31.26 1.8 3.06

23 25.69 7.3 53.58

24 28.71 4.3 18.49

Total 711.828 479.92

√

The calculation above shows that the smoothness has been improved to become

21.91. The next step is calculating the balance delay and efficiency as follows:

The calculation above shows the balance delay obtained after the additional action

process. The balance delay is decreased to 10 %. After obtaining the balance

delay, then the line efficiency can be obtained as follows:

Calculation above shows the efficiency after the additional action is implemented.

The line efficiency has been upgraded to 90%. Thus, the company’s target has

been obtained.

4.9 Comparison of Current and Proposed Line

As stated in the beginning, the purpose of this research is to increase the

efficiency of line M123. Thus, the comparison of proposed and the actual condition

of M123 is shown in the figure below:

57%

90%

0%

20%

40%

60%

80%

100%

Current Proposed

Efficiency

Efficiency

43%

10%

0%

10%

20%

30%

40%

50%

Current Proposed

Balance Delay

BalanceDelay

Figure 4. 16 Comparison between current and proposed line

Based on the graph shown in the figure above, it is clear that the proposed line is

much better than the previous one in terms of efficiency, balance delay, and

smoothness index. The efficiency increases from 57% to 90% and it has been

considered to fulfill the goal targeted by the company. The balance delay is

reduced up to 33% and smoothness index can be reduced.

Table 4. 23 The result of improvement

The improvement is not only by increasing efficiency, reducing balance delay,

and reducing smoothness index, it also includes the decrement number of

operator. Thus, the cost saving by applying this method can be calculated in the

table below.

Current Proposed Improvement

Efficiency 57% 93% 36%

Balance Delay 43% 7% 36%

Smoothness Index 65.86 21.91 43.95

65.86

21.91

0

10

20

30

40

50

60

70

Current Proposed

Smoothness Index

SmoothnessIndex

Table 4. 24 Cost comparison between actual and after improvement condition

Condition

# of

Opera

tor

Overtime

Monthly

operator

payment

Overtime Jig + Comb

investment Total

Current 34 68 110,840,000.00 1,360,000.00 - 112,200,000.00

Proposed 24 48 78,240,000.00 960,000.00 130,000.00 79,330,000.00

Total estimated saving per month

32,870,000.00

Note:

Minimun regional salary : IDR 3,260,000

Overtime wage : IDR 20,000 / hour

Jig price : IDR 100,000 / unit

Comb Price : IDR 15,000 / unit

It is obvious that the proposed line is much more profitable than the actual one.

The improvement condition still has to do the overtime since the cycle time

needed for the process is quiet high than the takt time must be adjusted too by

adding the number of working hour. In fact, it is still much profitable since the

number of operator can be decreased. Based on the cost saving analysis, the

company can save up to IDR 33,000,000 per month.

After calculating and analyzing all the data collected for this research, a new work

arrangement has been developed. The next chapter will provide the conclusion

and recommendation for future research.

CHAPTER V

CONCLUSION AND RECOMMENDATION

1.1 Conclusion

Based on the research that has been conducted, the conclusions are:

The root cause of having low efficiency is because the standard as the

guidance cannot accommodate the needs of actual condition and poor

work arrangement.

To increase the line efficiency, increasing the accuracy of each operation

is needed and continued by redesigning the work arrangement through the

line balancing method.

Based on the result, the research has achieved its objective as stated in the

beginning.

The line efficiency of M123 has increased to 32.89% from 57.11% to

90%

Number of operator in Line M123 can also be reduced by now only

utilizing 24 operators as the result of better efficiency.

1.2 Recommendation

Some of the production line at PT XY with the total number of operation exceed

35 usually experience low efficiency. The condition is worse when the toy

running in the production line may sometimes be changed based on the demand so

that re-arrangement is needed. Thus, the further research to increase the line

efficiency for the “complicated” toy is very beneficial.

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System, New York, Prentice Hall, 1985.

Hayter, A. Probability and Statistics for Engineers and Scientists 3rd Edition.,

Thomson.

Karger, D.W. & Bahya, F.H., Engineering Work Measurement 3rd Edition, New

York, The Industrial Press, 1977.

Niebel, B.W. & Freivalds, A., Niebel's Methods, Standards, and Work Design

12th Edition, New York, McGraw-Hill, 2003.

Pachghare, Vrittika V., Assembly Line Balancing Methods, Government College

of Engineering, 2012.

Sutalaksana, Iftikar Z., Anggawisastra, R. and Tjakraatmaja, J.H., Teknik

Perancangan Sistem Kerja, Bandung, ITB, 2006.

Taha, H., Operation Research: An Introduction 7th Edition, New Jersey, Prentice-

Hall, 2003.

Walpole, R.E., Myers, R.H., Myers, S.L. & Ye, K., Probability and Statistic for

Engineers and Scientists 7th Edition, New Jersey, Prentice-Hall, 2002.

Wignjosoebroto, S., Ergonomi, Studi Gerak dan Waktu. Surabaya, Guna Widya,

2000.

Minkjan, OBIEE Creating a Yamazumi Graph, 2010. Retrieved January 02, 2016,

from http://knowledge.ciber.nl/weblog/?p=183

Till, W., Tact Time, 2010. Retrieved November 12, 2015, from Kaizen Today:

http://kaizentoday.com/page/Pages/Tact-Time.aspx

http://knowledge.ciber.nl/weblog/?p=183

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