Joint Replenishment Problem for Multi Supplier One Regional

Laila Nafisah, Ahmad Muhsin, Bekti Sulistiyani, Yuni Siswanti

Universitas Pembangunan Nasional Veteran Yogyakarta

Keywords: Inventory, Joint Replenishment Problem, Multi Supplier, Probabilistic, ABC Analysis

Abstract: PT XYZ is a company that produces various bags with leather as its basic material. Request for bag

accessories as supporting raw material is uncertain (probabilistic). In view of accessories requests in the

monthly report of 2017 until 2018, there was out of stock to the value of 44%. Accessories request is not

performed in the unit, but only several accessories needed at that time. In consequence, after order is

submitted, request for additional accessories is added and makes the total request and order imbalance. The

order which is submitted several times in one month may increase inventory cost. Moreover, this research

uses the Joint Replenishment Order Method, which aims to control accessories stock. This method tries to

design control for the stock by taking into account request (Di), service level, and company's expense. The

first step of this method is determining the time between the order of each accessory(Ti), and then

determining the interval of basic order (T) in order to specify order optimal time (T*). After the optimal

time is specified, the quantity (Q), which will be ordered to the supplier, also safety stock and inventory

level for each item can be known. Stock control design will obtain the result of minimal inventory total cost.

Result of Joint Replenishment Order Method Calculation shows obtained order optimal time (T*) of 0,3558

years with the total cost to the value of Rp50.863.488; thus, in one year the obtained total cost is

Rp152.590.465 per year, while expenses with company method are to the value of Rp198.411.763. The

company can save cost up to Rp45.821.297 or 23% with this method.

1 INTRODUCTION

Inventories are idle resources, so their existence can

be seen as a waste due to the existence of embedded

capital that cannot be used. Inventory is also the

capital or assets of the company that is important for

the smooth production process in the company. If

the supply is insufficient, or there is a shortage of

inventory, the company will be faced with the

cessation of the production process, not achieving

the production target and the loss of consumer

confidence. Conversely, if there is too much

inventory, the company will bear the costs due to the

goods stored, the risk of damage to the goods, or

even the goods become out of date. Thus, the

company is faced with a dilemma that is one side of

the company wants to increase service level by

providing enough goods, and the other side is to

provide goods as minimal as possible to avoid losses

due to the risk of storing too many goods. Clearly,

the ability to satisfy consumers and simultaneously

reduce losses requires the application of good

inventory management principles.

PT XYZ is a company in Yogyakarta that

manufactures various types of leather-based bags.

One of the supporting raw materials in bag making

is accessories. This company has a diverse catalog of

bag models, where each bag model requires

accessories that can differ (vary) from one model to

another. There are 56 types of accessories managed

by companies that support the production of various

models of bags. All were ordered from 4 suppliers,

namely Prima Jakarta, 88 Buckle, Mitra Buckle, and

Beautiful Pattern. The four suppliers are located in

Jakarta. Each supplier orders several different items

(multi items).

The variety of bags produced and the uncertain

number of bag requests make it difficult for

companies to determine the stock of each item of

accessories that must be provided in the accessories

warehouse. Based on monthly reports on the need

for accessories in the last two years, there was an out

of stock of 44%. So ordering often happens several

times a month. As a result, the costs of messaging

and transportation costs are quite high. If this

continues, it will certainly make the company lose,

because it will hamper the smooth production of

Naﬁsah, L., Muhsin, A., Sulistiyani, B. and Siswanti, Y.

Joint Replenishment Problem for Multi Supplier One Regional.

DOI: 10.5220/0009958604010411

In Proceedings of the International Conference of Business, Economy, Entrepreneurship and Management (ICBEEM 2019), pages 401-411

ISBN: 978-989-758-471-8

401

bags, the target is not achieved, and the level of

consumer confidence in the company decreases.

The more accessories that are provided, the more

embedded capital that cannot be used for other

purposes that are more profitable, and the greater the

risk of the product being damaged. The fewer

accessories available, the greater the likelihood that

a shortage will occur. As a result, the greater the loss

of opportunities for profit.

Based on the above problems, it is necessary to

have a design in the ordering system to control the

supply of accessories that demand is probabilistic, so

that these accessories when needed are available in

the right amount in such a way that the costs

incurred are minimal and the production process is

realized.

The Joint Replenishment Model approach can be

used to help design the ordering system in such

cases. When a company located in Yogyakarta

orders several suppliers located in Jakarta, the

company needs to develop a shipping strategy in

order to minimize transportation costs arising from

ordering items from some of these suppliers. One

way is to consolidate all items designed for ordering

using the joint replenishment model approach from

several suppliers to be sent together to Yogyakarta.

The solution method used in determining the

ordering interval together that minimizes the costs

incurred is the heuristic method. While the ABC

method can be used to classify groups of accessories

according to the level of importance or priority of

each of these accessories.

The purpose of this research is to set an

appropriate time interval for multi-item accessories

that are ordered together from multi suppliers in

order to minimize transportation costs and message

costs and at the same time, minimize out of stock.

2 LITERATURE REVIEW

Inventories are materials or products or assets from

an association that is put away that will be utilized to

meet certain targets. Each component in an

organization must have stock in different structures

and capacities. In light of the physical structure, the

stock can be as crude materials, work in the

procedure, completed merchandise, save parts, and

supplies. While dependent on its capacity, the stock

is delegated a great deal size stock, variance stock,

and expectation stock.

Despite the fact that stock is an inactive asset, it

tends to be said that no organization works without

stock. Without provisions, business visionaries will

be looked at with the hazard that their organization

will, at one time, not have the option to satisfy the

wants of their clients. The level of stock of the

complete resources of the organization is moderately

high. For instance, at the manufacturing plant level,

around 25 - 35% of the absolute resources claimed.

While at the wholesaler level, 15 - 90% of the

absolute expense of items oversaw. Thusly, the

current stock in the organization should be overseen

just as conceivable, and the stock must be arranged

and controlled successfully and productively.

Stock control intends to keep up stock at an ideal

level with the goal that reserve funds are gotten from

expenses brought about. Assurance of stock strategy

or model that suits the genuine issue will deliver a

powerful stock control framework for the

organization. Stock models are partitioned into

deterministic models and probabilistic models. In the

deterministic stock model, the parameters that

influence the inventory framework (request, lead

time) are known with sureness. Though in the

probabilistic stock model, the parameters that impact

are not known with conviction. So there are three

explanations behind the significance of stock for

organizations, to be specific: the nearness of a

component of interest vulnerability, a component of

stockpile vulnerability from providers, and a

component of the vulnerability of the elegance time

frame among requesting and sending.

Regularly an association or organization is

looked at with issues of capacity and support of

various supplies, both crude materials, parts, and

completed products. In these conditions, the

executives must give exacting control need to kinds

of stock that have high esteem, though for

inventories with low-esteem control should be

possible rather freely, in light of the fact that too

tight power over this sort of control expenses might

be higher than the estimation of stock. For proficient

control, the stock must be grouped first. The

arrangement is normally isolated into three,

generally called ABC groupings. This idea was

presented by HF. Dickie during the 1950s. The order

depends on stock worth. With the information of this

grouping, the control will be done all the more

seriously on specific things, which are the most

significant things of every single existing thing

contrasted with different things.

Stock control by the ABC strategy is a stock

control method by considering gatherings of

merchandise as per the degree of significance of

each gathering of products. This strategy was found

by Pareto. In view of the Pareto standard,

merchandise is arranged into three gatherings, to be

ICBEEM 2019 - International Conference on Business, Economy, Entrepreneurship and Management

402

specific Class A, Class B, and Class C. Class A will

be a gathering of products that ingests about 80% of

the all-out capital gave and comprises of about 20%

of all merchandise oversaw. Class B is a gathering

of products that ingests about 15% of the all-out

capital gave (after class B) and comprised about

30% of all merchandise oversaw. Though class C is

the gathering of products that retain reserves, just

about 5% of all capital gave (outside classes An and

B) and comprised of about half of all merchandise

oversaw. At the point when an organization is

dealing with a multi-thing stock, and they arrange

recharging requests of things provided by a similar

provider. The related issue is known as the joint

renewal issue (JRP). The model is a joint recharging

model (JRM).

The fundamental idea of JRM is that few things

are requested from one provider utilizing similar

methods for transportation. The benefit of this JRM

is that it can limit the expense of messages and

transportation expenses acquired contrasted with

when requesting products separately. Requesting

and dispatching that is done all the while with bigger

parts and done once in a specific period for a wide

range of things required will surely have the option

to save money on message expenses and

transportation costs. Alternately, if a request is made

independently to a similar provider, there will be

rehashed orders. This, obviously, will make the

message expenses and transportation costs higher.

By deciding the ideal request time interim, the

correct request recurrence will be acquired with the

end goal that the expenses brought about can be

limited.

Research on joint recharging issues has been

done by a few scientists. Salameh et al., has looked

into JRM by thinking about item substitution. At the

point when the item requested at the provider level

isn't accessible, it is conceivable to supplant the

arranged thing. The examination centers around

quick-moving shopper products that have the

moderately deterministic interest are sold rapidly,

and with generally low costs, for example, toiletries,

and everyday necessities. Constrained work has been

done on stock-out based substitution under

deterministic interest inside the EOQ model setting.

Nagasawa et al. have been investigated about the

utilization of Genetic Algorithms for Can-Order

Policy on JRM. Research on JRP, where the item

under thought is an item that has weakening

properties, has been done by Li et al. In this

examination, the Joint recharging issue (JRP) model

with an exponential appropriation crumbling rate

was proposed. The target capacity of the JRP model

was to limit the arrangement costs, stock holding

expenses, and decay costs. Hereditary calculation

(GA) was utilized for tackling this issue and

inquired about were likewise made in angles, for

example, chromosome coding, wellness work,

determination, hybrid and transformation activities,

and so forth. The critical thinking arrangement

offered in this exploration is to utilize hereditary

calculations.

Wang et al. have been built up an Improved Fruit

Fly streamlining calculation (IFOA) to discover

answers for taking care of issues in JRP. The

outcome is IFOA can likewise be used to explain the

commonplace JRPs that have been demonstrated as

non-deterministic polynomial difficult issues.

Similar models uncover that the proposed IFOA can

discover preferred arrangements over the present

best calculation; consequently, it is a potential

device for different complex improvement issues.

While Tynan dan Kropp thinks about occasional

audit frameworks and joint recharging under

stochastic requests condition. To begin with, they

study the single item intermittent survey issue and

propose a basic arrangement method that is close

ideal. At that point, given the presence of this basic

system, they study the joint renewal issue for various

things under stochastic requests and propose basic

heuristics, which generally give excellent outcomes.

This examination finds the straightforward strategies

joined with the vigor of the cost capacity to be

appealing in different applications that require

coordination of process durations under stochastic

requests.

In view of a few past investigations, there has not

been much inquired about on the issue of the joint

recharged issue of multi-provider one locale. In this

examination, the JRP case will talk about where a

request is made by an organization to a few

providers in a similar region under stochastic

requests. Requesting a few things to every provider

depends on probabilistic requests with the JRM

approach. At that point, all requesting things from

every provider are solidified in a specific

distribution center to be sent together from Jakarta to

Yogyakarta. The arrangement strategy utilized in

deciding the requesting interim together that limits

the expenses brought about is the heuristic

technique.

3 EXPERIMENTS

This research is performed in PT XYZ Yogyakarta.

The research object is bag accessories in the number

Joint Replenishment Problem for Multi Supplier One Regional

403

of 56 items from January 2017 until December 2018.

Required research data involve data of request,

inventory costs, and lead time.

Table 1: Cost Data Collection

No Parameter Data

1 Request Data (D)

2 Purchase Price Data

3 Supplier Data

4 Order

Cost

Minor

(Administration,

telephone) (a) 20.000

Major

(transportation) (A)

Rp250.0

5 Storage Cost, Rp/item (h) Rp

2,663

6 Service level (z) 99%

7 Lead time, day (LT) 4

Table 2: Data of Request

No Code

Request

No Code

Request

No Code

Request

2017 2018 2017 2018 2017

2018

A01 15166 28878 20 A20 7000 1660 39

A39

6469 1680

A02 5327 20320 21 A21 7620 5878 40 A40 3000 996

A03 25186 34938 22 A22 19934 12713 41 A41 13655 12708

A04 21434 42796 23 A23 7169 3951 42 A42 15155 11701

A05 17649 15896 24 A24 4883 3321 43 A43 8328 14790

A06 15550 14382 25 A25 63490 49419 44 A44 2778 13456

A07 13541 13266 26 A26 3298 1147 45 A45 2618 1330

A08 15130 15207 27 A27 1624 1542 46 A46 21963 8945

A09 29118 51925 28 A28 27206 9186 47 A47 6218 2815

A10 6401 3423 29 A29 1603 1715 48 A48 4668 1638

A11 7206 6739 30 A30 6574 4356 49 A49 33000 29403

A12 7567 6773 31 A31 8000 2291 50 A50 39000 21326

A13 65425 52951 32 A32 7705 2625 51 A51 13516 8668

A14 5438 2978 33 A33 8513 3825 52 A52 11728 7768

A15 24200 19091 34 A34 5381 6658 53 A53 12923 10199

A16 2725 15274 35 A35 31600 21038 54 A54 13477 8281

A17 14067 15875 36 A36 1313 2321 55 A55 8829 7386

A18 13669 16393 37 A37 3255 1424 56 A56 3100 8953

A19 12741 16244 38 A38 3653 2310

ICBEEM 2019 - International Conference on Business, Economy, Entrepreneurship and Management

404

Table 3: Purchase Price Data

No Code

Price (Rp)

No Code

Price (Rp)

No Code

Price (Rp)

A01 1120 20 A20 360 39

A39

625

A02 750 21 A21 380 40 A40 632

A03 500 22 A22 395 41 A41 1050

A04 200 23 A23 410 42 A42 1150

A05 350 24 A24 425 43 A43 1190

A06 350 25 A25 175 44 A44 1205

A07 780 26 A26 210 45 A45 240

A08 507 27 A27 375 46 A46 495

A09 550 28 A28 425 47 A47 507

A10 820 29 A29 500 48 A48 550

A11 750 30 A30 675 49 A49 450

A12 450 31 A31 513 50 A50 180

A13 420 32 A32 575 51 A51 450

A14 300 33 A33 620 52 A52 180

A15 540 34 A34 650 53 A53 450

A16 300 35 A35 450 54 A54 500

A17 300 36 A36 500 55 A55 1350

A18 1150 37 A37 500 56 A56 750

A19 850 38 A38 619

Table 4: Supplier Data

Code Accessory Name Supplier Code Accessory Name Supplier

A01 Big Zipper

A35 Horse Buckle 1 cm

A02 Medium Zipper

A36 Horse Buckle 1,5 cm A

A05 Plastic YKK Zipper 05

A37 Horse Buckle 1,5 cm B

A06 Plastic YKK Zipper 03

A38 Horse Buckle 2,5 cm

A07 Metal YKK Zipper

A39 Horse Buckle 3,2 cm

Gesper

A08 Jacket YKK Zipper

Prima

A40 Horse Buckle 3,8 cm

A13 Zipper Head

Jakarta

A45 Buckle 1,5 cm

Joint Replenishment Problem for Multi Supplier One Regional

405

A14 Small Zipper Head

A46 Buckle 2,5 cm

A15 Leaf Zipper Head

A47 Buckle 3,5 cm

A16 Small Leaf Zipper Head 1

A48 Buckle 3,8 cm

A17 Small Leaf Zipper Head 2

A03 Button

A18 Metal Zipper Head NK

A04 Button Bearing

A19 Jacket Head Zipper

A10 Eyelet 1 cm

A20 Square Buckle 1,5 cm

A49 Solid Rivet T255

Mitra

A21 Square Buckle 2 cm

A50 Rivet Hole T255

Gesper

A22 Square Buckle 2,5 cm

A51 Solid Rivet T266

A23 Square Buckle 3 cm

A52 Rivet Hole T266

A24 Square Buckle 3,8 cm

A53 Short Rivet 277

A25 Ring D 1 cm

A54 Long Rivet 277

A26 Ring D 1,5 cm

Gesper

A09 Horse Chain

A27 Ring D 2 cm

A11 Ipod Rag

A28 Ring D 2,5 cm

A12 Ipod Rag Bearing

A29 Ring D 3 cm

A41 Roll Buckle 2 cm

Pola

A30 Ring D 3,8 cm

A42 Roll Buckle 2,5 cm

Indah

A31 Ring O 2 cm

A43 Roll Buckle 3,2 cm

A32 Ring O 2,5 cm

A44 Roll Buckle 3,8 cm

A33 Ring O 3,2 cm

A55 Magnet JP

A34 Ring O 3,8 cm

A56 Magnet HB

4 RESULTS

4.1 ABC Calculation

Step 1: Calculate the total cost per item

Step 2: Sorting out the total cost of each item from

the biggest until the smallest.

Step 3: Calculate the percentage of the total cost

Step 4: Classify each item into category A to the

value of 0-80%, category B to the value of 81%-

90%, and category C to the value of 91%-100%.

4.2 Distribution Test

The distribution test of request data is performed by

using Kolmogorov-Smirnov Method with SPSS. An

example of the calculation result can be seen in

Table 5.

ICBEEM 2019 - International Conference on Business, Economy, Entrepreneurship and Management

406

Table 5: Distribution test result

Note: Rit Besar = Big Zipper, Rit Sedang = Medium Zipper, Kancing = Button, Bantalan Kancing = Button

Bearing, Rit YKK Plastik 05 = Plastic YKK Zipper 05

4.3 Calculation of Joint Replenishment

Order

Iteration 1 for supplier 1

Step 1: Determining the value of T













(1)





220000

31,9622022

0,2383year.





∗







































(2)







20000



31,9622022

2,327471,821

0,23830,0125



0,2773year

Step 2: Identification of the smallest T

value is

notated as item 1, with value of k

= 1 and other

items are notated as item 2,3,4,..,n. the smallest T

value is A13 so that it is notated k

= 1

Step 3: Determining T Value























(3)















,





= 0,5343 year









































(4)













,







,,



,,,



= 0,5059 year

Step 4: Determining value of other k items in which

, k

, , k

with trial and error





1









∗









1



, k

= q

(k = 1) =





11





,

,







11



= 0  0,4493  1,4142

(fulfilled)

Step 5: Determining T* value











∑















∑





























,

= 0,3695 year

Step 6: Determining Total Cost (OT)







∑















∑

























































,



= 0,3558 year

Joint Replenishment Problem for Multi Supplier One Regional

407

Table 6: Input of data OT supplier 1 (iteration 1)

No Code Di









h k

















1 A01 22022 471,8210 1 20000 703831,6589 760602,5719

2 A02 12824 472,0729 1 20000 409844,0322 466645,2515

3 A05 16773 135,4311 1 20000 536055,6034 552351,0749

4 A06 14966 114,1129 1 20000 478319,163 492049,5679

5 A07 13404 90,4434 1 20000 428381,0571 439263,4785

6 A08 15169 125,9936 1 20000 484791,1415 499951,0645

7 A13 59188 1605,4512 1 20000 1891671,43 2084844,1178

8 A14 4208 159,9435 1 20000 134489,3116 153734,1932

9 A15 21646 660,2407 1 20000 691798,5729 771240,7091

10 A16 9000 320,9006 1 20000 287627,5095 326239,2267

11 A17 14971 230,4744 1 20000 478478,9649 506210,3350

12 A18 15031 234,6681 1 20000 480396,5882 508632,5526

13 A19 14493 250,1622 1 20000 463185,9194 493286,1812

Total 127830,08 7468870,95 8055050,325

OT =













∑

























zσ

√

TLT

∑















zσ

√

TLT





(8)



,





,







,







,,



,







2,327



471,821





0,35580,0125



22022



0,35580,0125



31,96





2,327



471,821



0,35580,0125

= Rp1.075.540

Based on the result of the calculation, it obtains the

total cost for supplier 1 on iteration 1 is to the value

of Rp13.359.289/year. The next stage is iteration 2

started with step 4. If the result of iteration 2 is

smaller or the same with the previous iteration, then

stop, but if the obtained result of iteration is bigger

than the previous one, then it shall be continued to

the next iteration. The calculation for supplier 2,

supplier 3, and supplier 4 is using the same steps. In

consequence, it obtains optimal time (T*) of 0,3558

years  4 months with a total cost of Rp50.863.488,

and for 1 year, the obtained total cost is

Rp152.590.465.

ICBEEM 2019 - International Conference on Business, Economy, Entrepreneurship and Management

408

Table 7 Result of recapitulation

Total cost (Rp)

TOTAL (Rp)

Supplier 1 Supplier 2 Supplier 3 Supplier 4

= 0,3558 13,359,289 20,982,163 9,034,423 7.487.613 50.863.488*

= 0,3962 13,483,820 21,159,823 9,198,838 7.348.389 51.190.870

= 0,3703 13,483,820 21,214,991 9,133,900 7.475.538 51.308.248

= 0,4229 13,694,912 20,992,152 9,214,931 7.732.542 51.634.537

4.4 Determining Order Quantity (Q)

Quantity obtains forecast result of 2019 and optimal

time (T*) of 0,3558 years. Forecast Result in 2019

uses Holt-Winters Additive Algorithm (HWA)

method and software WinQSB

Step 1: Determining the aggregate request.

Step 2: Determining the proportion of each item

Step 3: Calculating forecast by using software

WinQSB

Step 4: Calculating disaggregation

Step 5: Determining order quantity (Q) for each item















∗



(9)

4.5 Determining Safety Stock and

Inventory Level

Safety stock i = z







LT



(10)

Inventory level i = 



































Table 8: Quantity, Safety stock and Inventory level

No Code D

forecast

Q SS IL No Code D

forecast

Q SS IL

1 A01 21919 7800 784 8858 29 A29 1657 590 216 826

2 A02 12767 4544 683 5386 30 A30 5446 1938 290 2296

3 A03 29921 10648 629 11650 31 A31 5125 1824 279 2167

4 A04 31964 11375 707 12481 32 A32 5145 1831 268 2164

5 A05 16694 5941 356 6505 33 A33 6145 2187 190 2454

6 A06 14898 5302 181 5668 34 A34 5995 2134 227 2436

7 A07 13345 4749 273 5189 35 A35 26195 9322 918 10567

8 A08 15101 5374 293 5855 36 A36 1813 646 253 921

9 A09 40329 14352 1332 16187 37 A37 2334 831 274 1134

10 A10 4893 1742 268 2070 38 A38 2973 1058 224 1319

11 A11 6944 2472 161 2719 39 A39 4060 1445 297 1792

12 A12 7140 2541 175 2805 40 A40 1994 710 133 867

13 A13 58903 20961 3496 25193 41 A41 13123 4670 473 5307

Joint Replenishment Problem for Multi Supplier One Regional

409

14 A14 4194 1493 275 1820 42 A42 13369 4758 398 5323

15 A15 21545 7667 1353 9289 43 A43 11508 4096 299 4538

16 A16 8961 3189 378 3679 44 A44 8082 2876 363 3340

17 A17 14903 5304 394 5883 45 A45 1970 702 144 870

18 A18 14963 5325 469 5980 46 A46 15384 5475 535 6202

19 A19 14428 5135 504 5818 47 A47 4501 1602 218 1876

20 A20 4316 1536 167 1756 48 A48 3142 1119 211 1368

21 A21 6722 2393 280 2756 49 A49 31054 11051 2506 13944

22 A22 16249 5783 732 6718 50 A50 30020 10683 1048 12105

23 A23 5542 1973 310 2352 51 A51 11042 3930 346 4413

24 A24 4087 1455 184 1690 52 A52 9707 3455 281 3857

25 A25 56185 19994 1960 22656 53 A53 11510 4096 508 4748

26 A26 2217 789 201 1017 54 A54 10830 3854 483 4472

27 A27 1580 563 212 794 55 A55 8074 2874 525 3499

28 A28 18113 6446 2416 9088 56 A56 6002 2136 365 2576

4.6 Result Analysis

Based on data processing result, request data

classification is obtained by Activity-Based Costing

(ABC) in which Category A consists of 25 items and

needs inventory cost to the value of 78,64%,

category B consists of 9 items which need inventory

cost to the value of 11,71%, and category C consists

of 22 items which need inventory cost to the value

of 10,34%. Request data which has been tested using

Kolmogorov-Smirnov with SPSS are including as

normal data, since the result of Asym. Sig is more

than 0,05. Stock control uses a joint replenishment

method to determine optimal order time. Stock

control is performed based on order cost, storage

cost, service level, and lead time. Accessory order

cost consists of major cost to the value of Rp250.000

and minor cost to the value of Rp20.000, the storage

cost of Rp31,96 per item per year, service level to

the value of 99% and lead time for 4 days or 0,0125

years.

Based on recapitulation result, it obtains the

smallest total cost of Rp50.863.488 with optimal

time (T*) in which T*

during 0,3558 year or 4

months. Total cost, which is obtained by the joint

replenishment order method for 1 year, is to the

value of Rp152.590.465, while the company method

is to the value of Rp198.411.763. Stock control uses

a joint replenishment method is aimed to determine

the optimal time in performing the order so that it

may save the total cost expelled by the company.

The system of stock control uses this method, and

the company can save Rp45.821.297 per year or

23%.

5 CONCLUSIONS AND FUTURE

WORK

Based on the data processing result, it can be

concluded that the company in performing

accessories order is not considering order time and

ordered quantity; thus, order by using a joint

replenishment order method can determine the

optimal time, quantity, safety stock, and inventory

level, so it minimizes inventory cost. In this method,

optimal order time (T*) of 0,3558 years or 4 months

with the total cost of Rp50.863.488 and quantity (Q)

are obtained. So that in one (1) year, there are 3

times of order, and the total cost is Rp152.590.465

ICBEEM 2019 - International Conference on Business, Economy, Entrepreneurship and Management

410

per year cheaper than the total cost of the company

method of Rp198.411.763, therefore there is saving

cost up to Rp45.821.297 or 23 %.

ACKNOWLEDGMENTS

The authors would like to thank the Institute for

Research and Community Service (LPPM) of UPN

"Veteran" Yogyakarta and Ministry of Research,

Technology, and the Higher Education Republic of

Indonesia for facilitating this research in Research

Scheme and providing financial support to produce

this publication.

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