materials requirements planning
DESCRIPTION
Materials Requirements Planning. MRP. Suatu perusahaan dengan beberapa produk, menerima pesanan dalam beberapa perioda. Perusahaan perlu untuk mengatur bahan baku apa saja, berapa, dan kapan setiap bahan itu diperlukan agar biaya produksi bisa diminimalkan. - PowerPoint PPT PresentationTRANSCRIPT
Materials Requirements Materials Requirements PlanningPlanning
MRPMRP
• Suatu perusahaan dengan beberapa produk, menerima pesanan dalam beberapa perioda.
• Perusahaan perlu untuk mengatur bahan baku apa saja, berapa, dan kapan setiap bahan itu diperlukan agar biaya produksi bisa diminimalkan.
• Perlu juga dipertimbangkan kuantitas pesanan agar dimungkinkan menekan biaya inventory.
MRPMRP
• Untuk mengetahui kebutuhan bahan baku, perlu diketahui Bill of Material ( BoM) dari setiap produk.
• BOM = Resep = Formula
• BOM adalah material, bagian, komponen, unit atau proses yang diperlukan untuk menghasilkan suatu produk.
Bill of Materials (BOM) FileBill of Materials (BOM) FileA Complete Product DescriptionA Complete Product Description
• Materials
• Parts
• Components
• Production sequence
Part Description Quantity Number required
203 Wooden Leg 4411 Wooden End 2622 Wooden Sides 223 Table Top 1
722 Hardware Kit 1
Description : TablePart Number : 100
Simplified bill of material
Deskripsi BOM
Table100
Base 200
Top023
Legs (4)203
Boards (3)030
Leg Bolts (4)220
Frame (1)300
Sides (2)622
Ends (2)411
Leg Supports (4)
533
Glue 066
Glue 066
Multilevel Bill
Table100
Base 200
Top023
Legs (4)203
Boards (3)030Leg Bolts (4)
220Frame (1)
300
Sides (2)622
Ends (2)411
Leg Supports (4)
533
Glue 066
Glue 066
Single-level Bill
Base 200 Top
023
Frame (1)300
XY
L M N(2) O
P G
J K(2)
B(2) C D
F G(2) M(2) N
J K(2)
Using the following product tree, construct the appropriate single level trees. How many Ks are needed to make 100 Xs and 50 Ys?
Example Problem
Item Number
Week
1 2 3 4 5
C 50 125 25 50 150
A 50 25 25 50 50
B 100 100
A
DC
BC
Pegged requirements
Pegged requirements
Source of requirements
Pegging identify each parent item that created demand
Example of MRP Logic and Product Example of MRP Logic and Product Structure TreeStructure Tree
B(4)
E(1)D(2)
C(2)
F(2)D(3)
A
Product Structure Tree for Assembly A Lead TimesA 1 dayB 2 daysC 1 dayD 3 daysE 4 daysF 1 day
Total Unit DemandDay 10 50 ADay 8 20 B (Spares)Day 6 15 D (Spares)
Given the product structure tree for “A” and the lead time and demand information below, provide a materials requirements plan that defines the number of units of each component and when they will be needed
Given the product structure tree for “A” and the lead time and demand information below, provide a materials requirements plan that defines the number of units of each component and when they will be needed
LT = 1 day
Day: 1 2 3 4 5 6 7 8 9 10A Required 50
Order Placement 50
First, the number of units of “A” are scheduled backwards to allow for their lead time. So, in the materials requirement plan below, we have to place an order for 50 units of “A” on the 9th day to receive them on day 10.
First, the number of units of “A” are scheduled backwards to allow for their lead time. So, in the materials requirement plan below, we have to place an order for 50 units of “A” on the 9th day to receive them on day 10.
Next, we need to start scheduling the components that make up “A”. In the case of component “B” we need 4 B’s for each A. Since we need 50 A’s, that means 200 B’s. And again, we back the schedule up for the necessary 2 days of lead time.
Next, we need to start scheduling the components that make up “A”. In the case of component “B” we need 4 B’s for each A. Since we need 50 A’s, that means 200 B’s. And again, we back the schedule up for the necessary 2 days of lead time.
Day: 1 2 3 4 5 6 7 8 9 10A Required 50
Order Placement 50B Required 20 200
Order Placement 20 200
B(4)
E(1)D(2)
C(2)
F(2)D(3)
A
SparesLT = 2
4x50=200
Day: 1 2 3 4 5 6 7 8 9 10A Required 50
LT=1 Order Placement 50B Required 20 200
LT=2 Order Placement 20 200C Required 100
LT=1 Order Placement 100D Required 55 400 300
LT=3 Order Placement 55 400 300E Required 20 200
LT=4 Order Placement 20 200F Required 200
LT=1 Order Placement 200
B(4)
E(1)D(2)
C(2)
F(2)D(3)
A
40 + 15 spares
Part D: Day 6
Finally, repeating the process for all components, we have the final materials requirements plan:
Finally, repeating the process for all components, we have the final materials requirements plan:
©The McGraw-Hill Companies, Inc., 2001
13
Additional MRP Scheduling Additional MRP Scheduling TerminologyTerminology
• Gross Requirements
• Scheduled receipts
• Projected available balance
• Net requirements
• Planned order receipt
• Planned order release
MRP ExampleMRP Example
A(2) B(1)
D(5)C(2)
X
C(3)
Item On-Hand Lead Time (Weeks)X 50 2A 75 3B 25 1C 10 2D 20 2
Requirements include 95 units (80 firm orders and 15 forecast) of X in week 10
Requirements include 95 units (80 firm orders and 15 forecast) of X in week 10
A(2)
X
Day: 1 2 3 4 5 6 7 8 9 10X Gross requirements 95
LT=2 Scheduled receipts Proj. avail. balance 50 50 50 50 50 50 50 50 50 50
On- Net requirements 45hand Planned order receipt 4550 Planner order release 45A Gross requirements 90
LT=3 Scheduled receipts Proj. avail. balance 75 75 75 75 75 75 75 75
On- Net requirements 15 hand Planned order receipt 15 75 Planner order release 15 B Gross requirements 45
LT=1 Scheduled receipts Proj. avail. balance 25 25 25 25 25 25 25 25
On- Net requirements 20 hand Planned order receipt 20 25 Planner order release 20 C Gross requirements 45 40
LT=2 Scheduled receipts Proj. avail. balance 10 10 10 10 10
On- Net requirements 35 40 hand Planned order receipt 35 40 10 Planner order release 35 40 D Gross requirements 100
LT=2 Scheduled receipts Proj. avail. balance 20 20 20 20 20 20 20
On- Net requirements 80 hand Planned order receipt 80 20 Planner order release 80
It takes 2 A’s for each X
It takes 2 A’s for each X
Day: 1 2 3 4 5 6 7 8 9 10X Gross requirements 95
LT=2 Scheduled receipts Proj. avail. balance 50 50 50 50 50 50 50 50 50 50
On- Net requirements 45hand Planned order receipt 4550 Planner order release 45A Gross requirements 90
LT=3 Scheduled receipts Proj. avail. balance 75 75 75 75 75 75 75 75
On- Net requirements 15 hand Planned order receipt 15 75 Planner order release 15 B Gross requirements 45
LT=1 Scheduled receipts Proj. avail. balance 25 25 25 25 25 25 25 25
On- Net requirements 20 hand Planned order receipt 20 25 Planner order release 20 C Gross requirements 45 40
LT=2 Scheduled receipts Proj. avail. balance 10 10 10 10 10
On- Net requirements 35 40 hand Planned order receipt 35 40 10 Planner order release 35 40 D Gross requirements 100
LT=2 Scheduled receipts Proj. avail. balance 20 20 20 20 20 20 20
On- Net requirements 80 hand Planned order receipt 80 20 Planner order release 80
B(1)A(2)
X
It takes 1 B for each X
It takes 1 B for each X
A(2) B(1)
X
C(3)
Day: 1 2 3 4 5 6 7 8 9 10X Gross requirements 95
LT=2 Scheduled receipts Proj. avail. balance 50 50 50 50 50 50 50 50 50 50
On- Net requirements 45hand Planned order receipt 4550 Planner order release 45A Gross requirements 90
LT=3 Scheduled receipts Proj. avail. balance 75 75 75 75 75 75 75 75
On- Net requirements 15 hand Planned order receipt 15 75 Planner order release 15 B Gross requirements 45
LT=1 Scheduled receipts Proj. avail. balance 25 25 25 25 25 25 25 25
On- Net requirements 20 hand Planned order receipt 20 25 Planner order release 20 C Gross requirements 45 40
LT=2 Scheduled receipts Proj. avail. balance 10 10 10 10 10
On- Net requirements 35 40 hand Planned order receipt 35 40 10 Planner order release 35 40 D Gross requirements 100
LT=2 Scheduled receipts Proj. avail. balance 20 20 20 20 20 20 20
On- Net requirements 80 hand Planned order receipt 80 20 Planner order release 80
It takes 3 C’s for each A
It takes 3 C’s for each A
A(2) B(1)
C(2)
X
C(3)
Day: 1 2 3 4 5 6 7 8 9 10X Gross requirements 95
LT=2 Scheduled receipts Proj. avail. balance 50 50 50 50 50 50 50 50 50 50
On- Net requirements 45hand Planned order receipt 4550 Planner order release 45A Gross requirements 90
LT=3 Scheduled receipts Proj. avail. balance 75 75 75 75 75 75 75 75
On- Net requirements 15 hand Planned order receipt 15 75 Planner order release 15 B Gross requirements 45
LT=1 Scheduled receipts Proj. avail. balance 25 25 25 25 25 25 25 25
On- Net requirements 20 hand Planned order receipt 20 25 Planner order release 20 C Gross requirements 45 40
LT=2 Scheduled receipts Proj. avail. balance 10 10 10 10 10
On- Net requirements 35 40 hand Planned order receipt 35 40 10 Planner order release 35 40 D Gross requirements 100
LT=2 Scheduled receipts Proj. avail. balance 20 20 20 20 20 20 20
On- Net requirements 80 hand Planned order receipt 80 20 Planner order release 80
It takes 2 C’s for each B
It takes 2 C’s for each B
A(2) B(1)
D(5)C(2)
X
C(3)
Day: 1 2 3 4 5 6 7 8 9 10X Gross requirements 95
LT=2 Scheduled receipts Proj. avail. balance 50 50 50 50 50 50 50 50 50 50
On- Net requirements 45hand Planned order receipt 4550 Planner order release 45A Gross requirements 90
LT=3 Scheduled receipts Proj. avail. balance 75 75 75 75 75 75 75 75
On- Net requirements 15 hand Planned order receipt 15 75 Planner order release 15 B Gross requirements 45
LT=1 Scheduled receipts Proj. avail. balance 25 25 25 25 25 25 25 25
On- Net requirements 20 hand Planned order receipt 20 25 Planner order release 20 C Gross requirements 45 40
LT=2 Scheduled receipts Proj. avail. balance 10 10 10 10 10
On- Net requirements 35 40 hand Planned order receipt 35 40 10 Planner order release 35 40 D Gross requirements 100
LT=2 Scheduled receipts Proj. avail. balance 20 20 20 20 20 20 20
On- Net requirements 80 hand Planned order receipt 80 20 Planner order release 80
It takes 5 D’s for each B
It takes 5 D’s for each B
Schedule ReceiptSchedule Receipt
• Kerjakan kembali bila pada perioda 6 ada schedule receipt material D sebanyak 50 unit.
• Kerjakan kembali bila lot size C adalah 100.
A
DC
BC
Low Level Code
Part Low Level
A 0 B 1 C 1 2 D 2
A
B(2)
D(1) E(1)
C(1)
D(2) F(1)
Given the following product tree, explode, offset, and determine the gross and net requirements. All lead time are one week, and the quantities required are show in parentheses.The master production schedule call for 100 As to be availableIn week 5,. There are 20 Bs available.
A
B(2)
D(1) E(1)
C(1)
D(2) F(1)
Given the following product tree, explode, offset, and determine the gross and net requirements. All lead time are one week, and the quantities required are show in parentheses.The master production schedule call for 100 As to be availablein week 5, there is a schedule receipt of 100 Bs in week 1.There are 200 Fs available. All order quantities are lot-for-lot.
H
I(2)
J(2) K(3)
Given the following partial product tree, explode, offset, and determine the gross and net requirements for components H, I, J, and K. Lead time are 1, 2, 1, and 1 week, and the quantities required are show in parentheses.The master production schedule call for production of 50 Hs in week 3, and 80 in week5. There is a scheduled receipt of 100 Is in week 2,. There are 400 Js, and 400 Ks available.
ProdukKompone
n Jumla
hLead Time
size
AC 2
1 L4LD 3
BE 1
1 L4LC 1
CE 1
1 L4LF 2
DE 2
1 L4LC 1
E - - 1 100F - - 1 500
Suatu produk mempunyai Bill of Material seperti di bawah ini :Buatlah product tree dari produk A dan B.MPS menentukan agar produk A tersedia 50 unit pada perioda 4, dan produk BTersedia 100 unit pada perioda 5.Produk A telah tersedia 10 pada awal perioda serta komponen C dijadwalkan akan diterima pada perioda 2 sebesar 100. Buatlah MRP untuk semua komponen.
Lot Sizing in MRP ProgramsLot Sizing in MRP Programs
• Lot-for-lot (L4L)• Economic Order Quantity (EOQ)• Period Order Quantity (POQ)• Part Period Balancing (PBB)• Least Unit Cost (LUC)• Least average Total Cost (LTC) – Silver
Meal
Which one to use? -> The one that is least costly!
Week 0 1 2 3 4 5 6 7 8 9 10
GR 35 30 40 0 10 40 30 0 30 55
OHI 35 0 0 0 0 0 0 0 0 0 0
NR 30 40 10 40 30 30 55
POR 30 40 10 40 30 30 55
PORel 30 40 10 40 30 30 55
Lead Time = 1 mingguHolding cost = $2/unit/mingguSetups cost =$200; Lot size = 1
Lot for Lot
Biaya setup = 7*$200 = $1400Biaya Hold = 0 ( tidak ada inv)Total biaya = $1400
Week 0 1 2 3 4 5 6 7 8 9 10
GR 35 30 40 0 10 40 30 0 30 55
OHI 35 0 44 4 4 68 28 72 72 42 61
NR 30 6 2 13
POR 74 74 74 74
PORel 74 74 74 74
D=(35+30+ .. + 55) = 270Q= √((2*200*270)/20) = 74
EOQ
Biaya order = 4*$200 = $800Biaya Hold = (44+4+4+…..+61)*$2 = $790Total biaya = $800+$790 = $1590
Week 0 1 2 3 4 5 6 7 8 9 10
GR 35 30 40 0 10 40 30 0 30 55
OHI 35 0 50 10 10 0 60 30 30 0 0
NR 30 40 55
POR 80 100 55
PORel 80 100 55
EOI =EOQ/d = 74/27 = 3 periode; pemesanan setiap 3 periode
Periodic Order Quantity (POQ)
Biaya order = 3*$200 = $600Biaya Hold = (50+10+10+…..+30)*$2 = $380Total biaya = $600+$380 = $980
Part Period Balancing (PPB)Part Period Balancing (PPB)
• Menyeimbangkan biaya setup dan biaya holding dengan menggunakan Economic Part Period (EPP).
• EPP di definisikan sebagai rasio dari biaya setup terhadap biaya holding.
• Teknik PPB mengkombinasikan periode kebutuhan sehingga jumlah part period mendekati nilai EPP
Part Period Balancing
EPP = 200/2 = 100
Mencari pesanan yang mendekati EPP, dg dasar pemikiran Menyimpan 100 unit selama 1 periode sama dengan menyimpan50 unit selama 2 periode ( biaya penyimpanan sama )
Kombinasi Lot size Part Period ( inventory)periode
2 30 02,3 30+40=70 40*1p=402,3,4 30+40+0=70 402,3,4,5 30+40+0+10=80 40*1p+10*3p=702,3,4,5,6 30+40+0+10+40=120 230
Part period yg paling dekat dg EPP adalah 70, maka pesanan awal pada periode 2 sejumlah 80 unit untuk memenuhi demand pada periode 2-5.
Part Period Balancing
Kombinasi Lot size Part Period ( inventory)periode
6 40 06,7 70 306,7,8 70 306,7,8,9 100 120
Part period yg paling dekat dg EPP adalah 120, maka pesanan awal pada periode 6 sejumlah 100 unit untuk memenuhi demand pada periode 6-9.
Kombinasi Lot size Part Period ( inventory)periode
10 55 0
Week 0 1 2 3 4 5 6 7 8 9 10
GR 35 30 40 0 10 40 30 0 30 55
OHI 35 0 50 10 10 0 60 30 30 0 0
NR 30 40 55
POR 80 100 55
PORel 80 100 55
Tabel MRP
Part Period Balancing (PPB)
Biaya order = 3*$200 = $600Biaya Hold = (50+10+10+…..+30)*$2 = $380Total biaya = $600+$380 = $980
Least Unit Cost (LUC)Least Unit Cost (LUC)
• Metode Lot Sizing heuristik LUC menetapkan lot size yang memperhitungkan sejumlah periode demand sedemikain sehingga total biaya per unit minimum
Least Unit Cost
Kombinasi Lot size Kumulatif Total Cost periode kumulatif Cost per unit
2 30 200 200/30=6.672,3 30+40=70 200+40*2=280 280/70=42,3,4 30+40+0=70 280 280/70=42,3,4,5 30+40+0+10=80 200+70*2=340 340/80=4.25Replenishment pada awal periode 2, lot size = 70 untuk
memenuhi kebutuhan periode 2-4.5 10 200 200/10=205,6 50 280 280/50=5.65,6,7 80 400 55.6.7.8 80 400 55,6,7,8,9 110 600 5.82Replenishment pada awal periode 5, lot size = 80 untuk
memenuhi kebutuhan periode 5-8
Week 0 1 2 3 4 5 6 7 8 9 10
GR 35 30 40 0 10 40 30 0 30 55
OHI 35 0 40 70 30 0 0 55 0
NR 30 10 40 30
POR 70 80 85
PORel 70 80 85
Tabel MRP
Least Unit Cost
Biaya order = 3*$200 = $600Biaya Hold = (40+70+30+55)*$2 = $390Total biaya = $600+$390 = $990
Minimum Cost per PeriodeMinimum Cost per PeriodeSilver MealSilver Meal
• Teknik ini mencoba mengkombinasikan beberapa periode perencanaan (trial error) untuk mendapatkan rata-rata total biaya yang minimum
• Rata-rata biaya adalah jumlah order cost dan holding cost dari n periode dibagi dengan n.
Silver Meal
Kombinasi Lot size Kumulatif Rata-rata periode kumulatif Cost Total cost
2 30 200 200/1=2002,3 30+40=70 200+40*2=280 280/2=1402,3,4 30+40+0=70 280 280/3=93.332,3,4,5 30+40+0+10=80 200+70*2=340 340/4=852,3,4,5,6 120 660 660/5=132 Replenishment pada awal periode 2, lot size = 80 untuk
memenuhi kebutuhan periode 2-5.6 40 200 200/1=2006,7 70 200+30*2=260 260/2=130
6,7,8 70 260 260/3=86.676.7.8,9 100 440 440/4=110Replenishment pada awal periode 6, lot size = 70 untuk
memenuhi kebutuhan periode 6-99 30 200 200/1=20010 85 310 310/2=155
Week 0 1 2 3 4 5 6 7 8 9 10
GR 35 30 40 0 10 40 30 0 30 55
OHI 35 0 50 70 30 0 0 55 0
NR 30 10 40 30
POR 80 70 85
PORel 80 70 85
Tabel MRP
Silver Meal
Biaya order = 3*$200 = $600Biaya Hold = (50+10+10+30+55)*$2 = $310Total biaya = $600+$310 = $910
Metode Total Biaya
Lot for Lot 1400
EOQ 1500
POQ 980
PPB 980
LUC 990
Silver Meal 910*
Tabel Perbandingan
Dipilih yang terkecil
Diketahui biaya pesan untuk item A adalah $20 /order, biaya simpan$2/unit/periode. Tentukan jumlah order yang harus dipesan dan biaya minimal yang harus dikeluarkan, dan tentukan dengan metodeapa yang sebaiknya digunakan bila diketahui lead time 2 minggu, dan persediaan minggu lalu masih tersisa 35 unit.
Periode 1 2 3 4 5 6 7 8 Tot
Permintaan 5 15 10 15 10 11 13 10 89