การประชุมวิชาการ : การวิจยั ดาเนินงาน ประจาปี 2548
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การคัดเลือกวัตถุดบิ ที่เป็ นกลยุทธ์ ด้านการจัดซื้อด้ วยเทคนิคการสร้ างสถานการณ์
จาลอง กรณีศึกษาโรงงานตัดเย็บเสื้อผ้า
Using Simulation Techniques to Identify Strategic Sourcing Items: case
study of a garment factory
สายธาร กลิน่ ลูกอิน
Saithan Kinloogin
สาขาการจัดการโลจิสติกส์ บัณฑิตวิทยาลัยการจัดการและนวัตกรรม มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี
[email protected]
ธนัญญา วสุ ศรี
Thananya Wasusri
สาขาการจัดการโลจิสติกส์ บัณฑิตวิทยาลัยการจัดการและนวัตกรรม มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี
[email protected]
บทคัดย่ อ
ปั จจุบนั การดาเนิ นงานทางธุรกิจได้เปลี่ยนแปลงไปอย่างรวดเร็ ว การมีกรอบข้อตกลงทางการค้า (Free Trade
Agreement) ที่ ทาในลักษณะทวิภาคี หรื อกรอบการตกลงการค้าขององค์กรการค้าโลก (World Trade Organization,
WTO) ร ว ม ทั้ ง ก า ร พั ฒ น า อ ย่ า ง ร ว ด เ ร็ ว ข อ ง ร ะ บ บ เ ท ค โ น โ ล ยี สื่ อ ส า ร
ท า ใ ห้ ก า ร ด า เ นิ น ธุ ร กิ จ ต้ อ ง มี ก า ร ป รั บ เ ป ลี่ ย น ก ล ยุ ท ธ์ อ ย่ า ง ร ว ด เ ร็ ว
เพื่ อ ให้ ส ามารถรั ก ษาหรื อ เพิ่ ม ความสามารถทางการแข่ ง ขัน ที่ นั บ วัน จะทวี ค วามรุ น แรงขึ้ นอย่า งรวดเร็ ว ได้
อุ ต สาหกรรมสิ่ ง ทอเป็ นอุ ต สาหกรรมหนึ่ งที่ จ ะได้รั บ อิ ท ธิ พ ลต่ อ ปั จจัย ต่ า ง ๆ ไม่ ว่ า จะเป็ นกรอบการค้า เสรี
รวมทั้ งการเปิ ดตลาดสิ่ ง ทอของจี น ที่ มี ต ้น ทุ น ต่ า กว่ า ดัง นั้ นอุ ต สาหกรรมสิ่ ง ทอ จึ ง มี ค วามจ าเป็ นที่ จ ะต้อ ง
เพิ่มประสิ ทธิ ภาพในการแข่งขันโดยการนาเอาการจัดการโลจิสติกส์และโซ่อุปทานที่เป็ นกลยุทธ์การบริ หารจัดการที่จั
ดได้วา่ เป็ นกลยุทธ์ที่ช่วยเพิ่มความสามารถในการแข่งขันเข้ามาประยุกต์ใช้
ง าน วิ จั ย นี้ เป็ น ส่ ว น ห นึ่ ง ข อ ง โ ค ร ง ก าร น าร่ อ ง ข อ ง ส ถ าบั น พั ฒ น าอุ ต ส าห ก ร ร ม สิ่ ง ท อ
โ ด ย เ ป็ น ก า ร น า เ อ า เ ท ค นิ ค ก า ร จ า ล อ ง ส ถ า น ก า ร ณ์ (Simulation)
ม าใ ช้ ใ น ก าร คั ด เลื อ ก วั ต ถุ ดิ บ ที่ จ ะ เป็ น ก ล ยุ ท ธ์ ใ น ก าร ส ร้ าง โ ซ่ อุ ป ท าน ข อ ง โ ร ง ง าน ตั ว อ ย่ าง
ผลที่ได้จากการจาลองสถานการณ์ทาให้เห็นถึงปั จจัยหรื อวัตถุดิบที่มีผลกระทบต่อระยะเวลาในการส่งมอบผลิตภัณฑ์
คาหลัก การสร้างสถานการณ์จาลอง กลยุทธ์จดั ซื้อ อุตสาหกรรมสิ่ งทอ
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การประชุมวิชาการ : การวิจยั ดาเนินงาน ประจาปี 2548
Abstract
Nowadays, the way we do businesses is rapidly changing. Free Trade Area
Agreement, World Trade Organization Agreement and fast changing of information
technology systems have led to the era of globalization. As a result, organizations need to
quick response to the fast changing factors in order to stay competitive in businesses.
Textile industry has affected not only by those factors–Free Trade Area Agreement,
information technology–, but also by the low cost of China’s textile products. Thus, Thai
textile industry needs to be improved. Logistics and Supply Chain Management can be
said as a strategy that can be used to improve competitive advantages
This research is a part of the pilot project of Supply Chain Management
Implementation funded by Thailand Textile Institute (THTI). The objective of this
research is mainly to select strategic sourcing items in order to set up a supply chain
connection with respect to total lead time reduction and simulation technique was selected
as a tool.
Keywords: Simulation, Supply Strategy, Textile Industry
1. Introduction
In today’s highly competitive market enterprises face a rapidly changing world,
more global competition, including the free trade pressures. To survive in the
competitive market, the manufacturers cope with the challenge of reduction in delivery
lead time, product cost, service cost and inventory cost. Moreover, the challenges of
manufacturers are shifting from internal efficiency to Supply Chain efficiency. A
significant competitive advantage could not obtain by improving the efficiency of
products and processes alone, the manufacturers need to improve the efficiency of
product, process and supply chain (Olhager and Selldin, 2004, Fine, 1998).
Ballou (2004) stated that supply chain management is the integration of activities
–the flow and transformation of goods from the raw materials through to the end user, as
well as the associated information flows–through improved supply chain relationships, to
achieve a sustainable competitive advantage. To adopt a SCM strategy means enterprises
along a logistic network act together in a collaborative environment, pursuing common
objectives and exchanging continuously information in order to reduce uncertainties such
as demand, process, administrative and decision processes and inherent uncertainties
(Reiner and Trcka (2004), Terzi and Cavalieri (2004)).
The Logistics and Supply Chain Management concept has started to be widely
introduced and promoted in many educational journals, conferences, and workshops in
order to set common standard and best practices. The Thai government also realizes the
importance of Logistics and Supply Chain Management concept, which is evidenced in
the Information and Communication Technology (ICT) Policy of Thailand 2002–2007
under the 6th national strategic plan. It is also indicated that the textile and clothing
business is one of the industrial targets we need to emphasize. As a result, this pilot
project was initiated, supported by the Thailand Textile Institute, Ministry of Industry.
The aims of this paper are to identify factors or sourcing items affecting supply
chain performances of a garment industry and later on to design an appropriate supply
strategies leading to lead time reduction for the garment
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2. Literature review
To design supply chain strategies and practices, it was found that simulation has
been used as a tool as it is possible to reproduce and to test different decision–making
alternatives upon more possible foreseeable scenarios, in order to ascertain in advance the
level of optimality and robustness of a given strategy (Terzi and Cavalieri, 2004). Many
researchers have applied simulation to design and evaluate supply chain strategies and
operations. Naim and Berry (1996) showed the use of simulation to describe the dynamic
implications of various supply chain redesign strategies adopted by a major European
manufacturer of personal computers. Cheng and Duran (2004) presented a decision
support system to investigate and improve the combined inventory and transportation
system of a world–wide crude oil transportation. An integration of discrete event
simulation and stochastic optimal control of the inventory/transportation system were
applied. Reiner and Trcka (2004) pointed out that an analysis of a supply chain must be
very specific. They developed a discrete event simulation to analyze performances in
different supply chain strategies.
Chang and Makatsoris (2001) noted that to achieve high quality, low cost with
minimal lead time, companies need to have a better visibility into the entire supply chain.
Developing simulation models of a supply chain can give a better understanding of the
supply chain characteristics. Simulation can also deliver powerful what–if analyses to
companies leading to better planning decisions. In addition to these, Terzi and Cavalieri
(2004) made a comprehensive reviewed on more than 80 articles. They concluded that
simulation tools are more suitable and deriving useful prescriptions both for practitioners
and researchers on its applicability in decision-making processes within the supply chain
context.
It can be seen that simulation is a very useful tool for designing a supply strategy.
We therefore selected the ARENA–a discrete event simulation tool–to gain a better
understanding of the garment industry and to identify strategic sourcing items.
3. Research Methodology
The research objective was to discover factors or sourcing items influencing the
supply chain performance which is lead time performance. To achieve the research
objective, simulation was then conducted. The procedures for the simulation study of
supply chain management are as follows:



Understanding business process of the garment
Design scenario to achieve the lead time performance
Conduct simulation modeling
4. Understanding business process
The garment industry is a Made to Order (MTO) producer. It produces lady and
children cloth which are fashion and mass customized. Nowadays, it is hardly to have a
repeated order because the product life cycle becomes shorter as a result of highly
competitive in global textile industry. Therefore, the garment must be very flexible for
the fast changing environment. The customer has sent its requirements to the garment 6
months before a new season starts. The requirements are included of product
specifications, quantity in total, colors and delivery date. The customer keeps updating
on the amounts and colors until a week before placing an order. The requirements will
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then be certain. Therefore, the requirement of colors and quantity for each size are
known at that time, but the information will not be given to its suppliers until the garment
will be placed orders by its customers. The business flow of the garment can be shown
in figure 1.
Customer
place order
Place P/O
Wait for Packaging
Wait for
Accessories
Wait for Fabric
Cutting
Sewing
Wait for Printing
Packaging
Figure 1 the Garment’s Business Flow
The garment business flow starts from the arrival of customer orders. After the
orders arrive, purchasing orders will be established and sent to suppliers such as fabric
supplier, packaging supplier, accessories supplier and printing supplier. The production
can really start when fabric arrives at the garment. If the fabric is needed to be printed,
the fabric will be cut and sent to the printing supplier. When the fabric is printed, sewing
process can then start. However, sewing accessories such as zip, button and label have to
be matched together before starting the sewing process. After finishing the sewing
process, packaging can then be started. In conclusion, there are 5 sources of delay time in
sourcing process that are waiting for fabric, waiting for printing, waiting for accessories,
waiting for packing and packaging process. Those 5 sources of delay time directly affect
the total lead time. Therefore, we need to identify which one has the most influence on
the total lead time.
5. Design Scenario
Five business strategies were proposed in order to do what–if simulation to find
out strategic sourcing items that could reduce total lead time for the garment. The five
business strategies are involved with 7 main factors that are waiting for fabric, cutting
process, waiting for printing, waiting for accessories, sewing process, waiting for packing
and packaging process. The five strategies can be summarized in table 1.
การประชุมวิชาการ : การวิจยั ดาเนินงาน ประจาปี 2548
Strategy
1
2
3
4
5
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Table 1 Five Business Strategies
Description
As–Is process to investigate total lead time
Implement supplier relationship management on fabric and reduce waiting
for fabric by 10%, 20% and 30%
Implement supplier relationship management on printing and reduce
waiting for printing by 10%, 20% and 30%
Implement supplier relationship management on packing and reduce
waiting for packing by 10%, 20% and 30%
Implement supplier relationship management on accessories and reduce
waiting for accessories by 10%, 20% and 30%
Strategy 1 is the as–is strategy that are no supplier improvement program and no
effort to evaluate or persuade its suppliers to achieve better lead time. The concentration
of the garment is only to reduce time at sewing process. The other strategies are to
investigate what is the main source that has the most impact on total lead time. In other
words, we can prioritize the job that we should conduct at a time. Strategy 2 is to find
out the impact of fabric on the total lead time by assuming that supplier relationship
management (SRM) is applied and SRM could lead to fabric delay time reduced by 10%,
20% and 30% respectively. Strategy 3 is to investigate the effect of printing time at a
supplier source. Strategy 4 and 5 are to investigate the effect of waiting time for packing
and waiting time for accessories on total lead time respectively. All strategies were
investigated their effect on total lead time by reducing their delay time by 10%, 20% and
30% respectively.
6. Simulation study
Arena–a discrete event simulation–has been selected as a tool. The simulation
construction was started from gathering data from the garment. The period of time that
are of our interest is during a high season of the garment ranging from June to December.
The real data from the garment such as customer orders, sewing process time, cutting
process time and so on are fitted distributions by Input Analyzer Module of Arena. Then,
the simulation program was constructed and it was verify by ARENA’s check module to
find whether or not there is a syntax error. One piece flow was then used to see if the
entity flow through the process as we had expected it. Lastly, comparison the results
between the simulation run and real data are our ways to validate the program. The input
analyzer example is shown on figure 2. The input analyzer module gives us Chi–Square
goodness of fit test. If p-value of the test is higher than  = 0.05, we will use the proposed
distribution. If the module cannot provide p-value higher than 0.05, we will use an
empirical distribution.
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Figure 2 The Input Analyzer
After we identified all input data, we developed a simulation program as shown in
figure 3. We then run the simulation for 10 replication and each replication for the high
season period (June–December). We get average total lead time equals to 113.37 days
with half width equals to 3.80. With the half width of 3.80, it is our acceptable value.
Therefore, 10 replication run is enough for our study. Figure 4 shows results from our
AS–IS run.
Figure 3 The Arena Program Construct
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Figure 4 The results of As-Is run
7. Results
Our as–is simulation run indicates that average total lead time is 113.37 days. We
then reduce the delay time of fabric, printing, packaging and accessories according to
table 1. The comparison of the time reduction by 10% of each strategy can be seen in
table 2.
Table 2 The Comparison of 10% reduction on each strategy
Strategy
Base
Total
Reduced
Total
Total
% of
Case
Lead
10%
Lead
Lead
Reduction
Time
Time
Time
Reduced
2 : fabric
73
113
66
107
6
5%
3: Printing
7
113
6
112
1
1%
4:Packaging
63
113
57
113
0
5:Accessories
65
113
59
113
0
From table 2, it can be seen that 10% reduction of fabric can reduce total lead time
by 5%. If strategy 3 was implemented with 10% lead time reduction, total lead time
would be reduced by 1%. However, the reduction of lead time in waiting packaging and
lead time in waiting accessories do not have any impacts on total lead time. We then run
the simulation again with reduce lead time by 20% for the four strategies. The results
show in table 3.
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Table 3 The Comparison of 20% reduction on each strategy
Strategy
Base
Total
Reduced
Total
Total
% of
Case
Lead
10%
Lead
Lead
Reduction
Time
Time
Time
Reduced
2 : fabric
73
113
58
99
14
12%
3: Printing
7
113
5
111
2
2%
4:Packaging
63
113
50
113
0
5:Accessories
65
113
52
113
0
It can be seen from table 3 that reduction time on packaging lead time and
accessories lead time do not affect on total lead time. Fourteen days can be reduced, if
we could reduced fabric sourcing lead time by 20%. Waiting time for printing has small
impacts on total lead time, as 20% of total lead time could be reduced when a 20% of
reduction on waiting time for printing is conducted. Finally, the 30% of lead time
reduction at each source was simulated. Table 4 also indicates that waiting time for fabric
directly affects on total lead time. Waiting for packaging, waiting time for accessories do
not affect on total lead time.
Table 4 The Comparison of 30% reduction on each strategy
Strategy
Base
Total
Reduced
Total
Total
% of
Case
Lead
10%
Lead
Lead
Reduction
Time
Time
Time
Reduced
2 : fabric
73
113
51
95
18
16%
3: Printing
7
113
4
110
3
3%
4:Packaging
63
113
44
113
0
5:Accessories
65
113
46
113
0
-
8. Conclusion
From the simulation environment, we reduce the lead time at each source
independently at a time. The main reason of conducting the environment is to identify
strategic sourcing items. The simulation results suggest us that reduction of time in
packaging sourcing time or accessories sourcing time alone will not be beneficial on total
lead time. Fabric is the main sourcing item that we should concentrate and supplier
improvement program or supplier relationship management program should be started for
fabric supplier.
To implement supplier relationship management program, we can divide the
program into three phases. First phase, we call it “pre–transaction” phase. This phase is
to setup supply strategy. Strategic sourcing items and strategic suppliers will be defined
in this phase. Supplier improvement program and supplier certification program will be
also conducted at this stage. Then, at the end of phase one, the strategic sourcing items
and strategic suppliers will be identified. The second stage (product development phase)
will concern on research and development with the strategic suppliers in order to improve
quality and service to the end customer of the supply chain. Third stage (order fulfillment
phase) is implementation of information technology in order to book or reserve the
supplier capacity. The last stage (post transaction phase) is to evaluate the strategic
suppliers or the strategic items.
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References
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