CONCLUSION AND SUGGESTION MINIMIZING INVENTORY COST OF WELL SANITARY IN CV ROJO SOLO.
CHAPTER 6
CONCLUSION AND SUGGESTION
6.1. Conclusion
After
all
simulation
and
analysis
process
have
been arranged, there are several conclusions could be
made to control the inventory of Well Sanitary at CV
Rojo. The conclusions based on the result of simulation
are used to answer the objectives of this research,
they are:
1. The simulation which gives the best result is the
simulation with fixed order period and considering
the discount of delivery cost. The order will be
scheduled every four days, and the limit of order
quantity is 25 mixed items for each order period.
Schedules of order are 4 days period, but the order
decision depends on the reorder point (ROP). The
order quantity is calculated by subtracting TSL with
the number of stock.
When the order quantity is lower than 25 items,
there should be an additional order based on the
inventory ratio, the lowest will be chosen first.
The lower inventory ratio makes the greater demand
that possible to occur.
2. The ROP and TSL for the best scenario are shown in
table 6.1.
_____________________________________________________
Table 6.1. ROP and TSL for Best Scenario
type color
ROP
TSL
8840 white
23
32
95
Table 6.1.(Continued)
type color
ROP
TSL
8840 ivory
8
15
8840 blue
3
5
8840 beige
3
4
8840 pink
4
5
8840 grey
3
4
8840 black
5
10
8901 white
13
20
8901 ivory
6
10
8901 blue
3
9
8901 beige
3
6
8901 pink
3
6
8701 white
28
43
8701 ivory
14
20
8701 blue
2
3
8701 beige
3
6
8701 pink
3
6
8808 white
17
29
8808 ivory
10
17
8808 blue
3
6
8808 beige
3
5
8808 pink
2
4
9888 white
15
27
9888 ivory
13
18
3888 white
30
52
3888 ivory
13
16
b212 white
8
13
b212 ivory
4
5
b212 black
5
12
96
Table 6.1.(Continued)
type color
ROP
TSL
bu05 white
10
13
bu05 ivory
9
13
_____________________________________________________
3. The number of replication for the best scenario is 3
replications.
4. Total holding cost for Well Sanitary at CV Rojo on
real
condition
simulation
is
model
Rp
9,839,790.96
result
is
Rp
and
the
best
6,311,704.11
in
average; so there is a decreasing cost as much as Rp
3,528,086.85 or 35.86%.
5. The stockless for Well Sanitary at CV Rojo on real
condition is 119 items during 2011, and based on the
result, the simulation reduces all the stockless as
much as 100%.
6. The total inventory cost for Well Sanitary at CV
Rojo on real condition is Rp 37,836,790.96 and the
average
of
total
inventory
cost
on
the
best
simulation model is Rp 37,190,704.11; there is a
decreasing cost as much as Rp 646,086.85 or 1.71%.
6.2. Suggestion
In order to reach optimum inventory, CV Rojo needs
to improve their inventory management, including manage
the order schedules, ROP, and order quantity to reduce
stockless and overstock. Improved inventory management
is also needed to minimize the inventory cost.
Considering the limit of order quantity to get the
discount of delivery cost might reduce the inventory
97
cost, however the additional order of products should
be noted. Doing continuous improvement on the ordering
policy by considering the discount aspect can be great
input for the next research.
98
References
Fransisca, 2011, Analisis Pengendalian Persediaan Spare
Part Sepeda Motor Honda di PT Menara Agung, Thesis
of
Industrial
Industrial
Engineering
Technology,
Program,
Universitas
Faculty
Atma
of
Jaya
Yogyakarta, Yogyakarta.
Heizer,
J.,
Render,
B.,
2005,
Operation
Management,
Seventh Edition, Prentice Hall, New Jersey.
Law, M., Kelton W.D., 2000, Simulation Modeling and
Analysis, Third Edition, McGraw Hill, Singapore
Poernomo, H. Nugroho, 2011, Analisis Persediaan Produk
di
UD
Modern,
Program,
Thesis
Faculty
of
of
Industrial
Industrial
Engineering
Technology,
Universitas Atma Jaya Yogyakarta, Yogyakarta.
Richi, Thomas Maria, 2006, Analysis of Inventory System
Using Simulation (Case Study at PT. Ekadharma Tape
Industries),
Thesis
Engineering
Program,
Technology,
of
Universitas
International
Industrial
Faculty
of
Industrial
Jaya
Yogyakarta,
Atma
Yogyakarta.
Tersine, Richard J., 1994, Principles of Inventory and
Material Management, Fourth Edition, Prentice Hall
Inc., New Jersey.
Waters, C.D.J., 2003, Inventory Control and Management,
John Wiley & Sons, New York
Walpole, Myers, YE, 2002, Probability & Statistics: For
Engineers & Scientists, Seventh Edition, Prentice
Hall Inc., New Jersey.
Winata, Predian., 2009, Analisis Kebijakan Perencanaan
Detergent dan Pewangi di Princess Laundry, Thesis
99
of
Industrial
Industrial
Engineering
Technology,
Program,
Universitas
Faculty
Atma
Yogyakarta, Yogyakarta.
http://easycalculation.com/statistics/critical-ttest.php
http://en.wikipedia.org/wiki/inventory
http://en.wikipedia.org/wiki/microsoft_excel
http://en.wikipedia.org/wiki/student’s_t-test
100
of
Jaya
CONCLUSION AND SUGGESTION
6.1. Conclusion
After
all
simulation
and
analysis
process
have
been arranged, there are several conclusions could be
made to control the inventory of Well Sanitary at CV
Rojo. The conclusions based on the result of simulation
are used to answer the objectives of this research,
they are:
1. The simulation which gives the best result is the
simulation with fixed order period and considering
the discount of delivery cost. The order will be
scheduled every four days, and the limit of order
quantity is 25 mixed items for each order period.
Schedules of order are 4 days period, but the order
decision depends on the reorder point (ROP). The
order quantity is calculated by subtracting TSL with
the number of stock.
When the order quantity is lower than 25 items,
there should be an additional order based on the
inventory ratio, the lowest will be chosen first.
The lower inventory ratio makes the greater demand
that possible to occur.
2. The ROP and TSL for the best scenario are shown in
table 6.1.
_____________________________________________________
Table 6.1. ROP and TSL for Best Scenario
type color
ROP
TSL
8840 white
23
32
95
Table 6.1.(Continued)
type color
ROP
TSL
8840 ivory
8
15
8840 blue
3
5
8840 beige
3
4
8840 pink
4
5
8840 grey
3
4
8840 black
5
10
8901 white
13
20
8901 ivory
6
10
8901 blue
3
9
8901 beige
3
6
8901 pink
3
6
8701 white
28
43
8701 ivory
14
20
8701 blue
2
3
8701 beige
3
6
8701 pink
3
6
8808 white
17
29
8808 ivory
10
17
8808 blue
3
6
8808 beige
3
5
8808 pink
2
4
9888 white
15
27
9888 ivory
13
18
3888 white
30
52
3888 ivory
13
16
b212 white
8
13
b212 ivory
4
5
b212 black
5
12
96
Table 6.1.(Continued)
type color
ROP
TSL
bu05 white
10
13
bu05 ivory
9
13
_____________________________________________________
3. The number of replication for the best scenario is 3
replications.
4. Total holding cost for Well Sanitary at CV Rojo on
real
condition
simulation
is
model
Rp
9,839,790.96
result
is
Rp
and
the
best
6,311,704.11
in
average; so there is a decreasing cost as much as Rp
3,528,086.85 or 35.86%.
5. The stockless for Well Sanitary at CV Rojo on real
condition is 119 items during 2011, and based on the
result, the simulation reduces all the stockless as
much as 100%.
6. The total inventory cost for Well Sanitary at CV
Rojo on real condition is Rp 37,836,790.96 and the
average
of
total
inventory
cost
on
the
best
simulation model is Rp 37,190,704.11; there is a
decreasing cost as much as Rp 646,086.85 or 1.71%.
6.2. Suggestion
In order to reach optimum inventory, CV Rojo needs
to improve their inventory management, including manage
the order schedules, ROP, and order quantity to reduce
stockless and overstock. Improved inventory management
is also needed to minimize the inventory cost.
Considering the limit of order quantity to get the
discount of delivery cost might reduce the inventory
97
cost, however the additional order of products should
be noted. Doing continuous improvement on the ordering
policy by considering the discount aspect can be great
input for the next research.
98
References
Fransisca, 2011, Analisis Pengendalian Persediaan Spare
Part Sepeda Motor Honda di PT Menara Agung, Thesis
of
Industrial
Industrial
Engineering
Technology,
Program,
Universitas
Faculty
Atma
of
Jaya
Yogyakarta, Yogyakarta.
Heizer,
J.,
Render,
B.,
2005,
Operation
Management,
Seventh Edition, Prentice Hall, New Jersey.
Law, M., Kelton W.D., 2000, Simulation Modeling and
Analysis, Third Edition, McGraw Hill, Singapore
Poernomo, H. Nugroho, 2011, Analisis Persediaan Produk
di
UD
Modern,
Program,
Thesis
Faculty
of
of
Industrial
Industrial
Engineering
Technology,
Universitas Atma Jaya Yogyakarta, Yogyakarta.
Richi, Thomas Maria, 2006, Analysis of Inventory System
Using Simulation (Case Study at PT. Ekadharma Tape
Industries),
Thesis
Engineering
Program,
Technology,
of
Universitas
International
Industrial
Faculty
of
Industrial
Jaya
Yogyakarta,
Atma
Yogyakarta.
Tersine, Richard J., 1994, Principles of Inventory and
Material Management, Fourth Edition, Prentice Hall
Inc., New Jersey.
Waters, C.D.J., 2003, Inventory Control and Management,
John Wiley & Sons, New York
Walpole, Myers, YE, 2002, Probability & Statistics: For
Engineers & Scientists, Seventh Edition, Prentice
Hall Inc., New Jersey.
Winata, Predian., 2009, Analisis Kebijakan Perencanaan
Detergent dan Pewangi di Princess Laundry, Thesis
99
of
Industrial
Industrial
Engineering
Technology,
Program,
Universitas
Faculty
Atma
Yogyakarta, Yogyakarta.
http://easycalculation.com/statistics/critical-ttest.php
http://en.wikipedia.org/wiki/inventory
http://en.wikipedia.org/wiki/microsoft_excel
http://en.wikipedia.org/wiki/student’s_t-test
100
of
Jaya