Inventory Management, contoh (1)
Menghitung EOQ dengan cara trial and errorl
Kebutuhan pertahun: 8000 unit
Biaya sekali order: 12.5 (ribu rp)
Biaya penyimpanan: 20% dari nilai barang per tahun
Harga barang: 1 (ribu rp)
Jumlah order Lot size rerata inventory / Nilai rerata biaya penyimpanan
tahun inventory /tahun
1 8000 4000 4000 800
2 4000 2000 2000 400
4 2000 1000 1000 200
8 1000 500 500 100
16 500 250 250 50
Inventory Management, contoh (2)
Menghitung EOQ dengan perhitungan aljabar
Dari contoh (1)
2DS 200000
2DS/H 1000000
EOQ 1000
Biaya order Total
biaya
12.5 812.5
25 425
50 250
100 200
200 250
Inventory Management, contoh (3)
Menghitung perkiraan kebutuhan
Tahun Kebutuhan (ton)
1 2
2 3
3 6
4 10
5 8
6 7
7 13
8 14
9 14
10 18
11 19
Inventory Management, Contoh (3)
Klasifikasi ABC
No N(Rp) UPT(unit/th) NPT(Rp/th) %NPT %NPT kum KELAS
1 50 50000 2500000 38.6
2 110 2000 220000 3.4
3 160 400 64000 1.0
4 80 700 56000 0.9
5 70 4800 336000 5.2
6 150 1300 195000 3.0
7 150 17000 2550000 39.4
8 200 300 60000 0.9
9 90 5000 450000 6.9
10 120 400 48000 0.7
Total 6479000
Catatan: Satuan Rp dikali 1000
urutan berdasar NPT dan perhitungan prosentase
No N(Rp) UPT(unit/th) NPT(Rp/th) %NPT %NPT kum KELAS
7 150 17000 2550000 39.4 39.4 A
1 50 50000 2500000 38.6 77.9 A
9 90 5000 450000 6.9 84.9 B
5 70 4800 336000 5.2 90.1 B
2 110 2000 220000 3.4 93.5 B
6 150 1300 195000 3.0 96.5 C
3 160 400 64000 1.0 97.5 C
8 200 300 60000 0.9 98.4 C
4 80 700 56000 0.9 99.3 C
10 120 400 48000 0.7 100.0 C
Contoh MPS
A B C D Std. Cap
L1 15 20 15 40
L2 20 20 30 10 40
L3 25 25 20 15 40
Week 1 We
Produk A B C D Cap used A
Initial Inventory 100 300 250 350 0
Gross requirement 2000 400 500 1000 600
Standar lot size 200 200 200 200 200
Safety inventory 400 500 400 300 400
Net requirement 2400 600 800 1000 1000
L1 600 40
L2 800 40
MPS
L3 720 48
Total 800 0 600 720 0
Reqirement met 900 300 500 1000 0
Requirement not met 1100 100 0 0 600
Service level 0.45 0.75 1.00 1.00 0.00
Avergage service level in the period 0.80 0.75
Ending inventory 0 0 350 70 0
Average inventory in the period 50 150 300 210 0
Total avg inventory in the period 710 470
Below safety inventory 400 500 50 230 400
Below safety inventory in the period 1180 1080
Week 2 Week 3
B C D Cap used A B C D Cap used A
0 350 70 0 150 300 70 0
650 650 600 700 650 650 600 200
200 200 200 200 200 200 200 200
500 400 300 400 500 400 300 400
1200 800 1000 1200 1000 800 1000 600
600 40 0
800 40 0
600 40 600 40
800 600 600 0 0 0 600 0
650 650 600 0 150 300 600 0
0 0 0 700 500 350 0 200
1.00 1.00 1.00 0.00 0.23 0.46 1.00 0.00
0.75 0.42 0.0
150 300 70 0 0 0 70 0
75 325 70 0 75 150 70 0
470 295 35
350 100 230 400 500 400 230 400
1080 1530 160
Week 4
B C D Cap used
0 0 70
650 300 600
200 200 200
500 400 300
1200 800 1000
0
0
0
0 0 0
0 0 70
650 300 530
0.00 0.00 0.12
0.03
0 0 0
0 0 35
35
500 400 300
1600
CONTOH PERHITUNGAN MRP
MPS
Perioda 1 2 3
A 400 600 600
B 200 0 0
ITEM
F
Perioda 1 2 3
F-A 800 1200 1200
F-B 200 0 0
Gross requirement 1000 1200 1200
Scheduled receive 800 1000
Initial Inventroy 400 200 0
Net requirement 0 0 1200
Planned receive 1200
End Inventory 200 0 0
Planned order 1200 900
G
Perioda 1 2 3
G- A 400 600 600
Gross requirement 400 600 600
Scheduled receive
Initial Inventroy 600 200 0
Net requirement 0 400 600
Planned receive 400 600
End Inventory 200 0 0
Planned order 400 600 400
H
Perioda 1 2 3
H-G 400 600 400
Gross requirement 400 600 400
Scheduled receive 600
Initial Inventroy 200 200
Net requirement 0 400 200
Planned receive 600 200
End Inventory 200 200 0
Planned order 600 200 0
I
Perioda 1 2 3
I-G 800 1200 1200
Gross requirement 800 1200 1200
Scheduled receive 1000
Initial Inventroy 1000 200 0
Net requirement 0 0 1200
Planned receive 1200
End Inventory 200 0 0
Planned order 1200 900
J
Perioda 1 2 3
F-B 400 0 900
Gross requirement 400 0 900
Scheduled receive 400
Initial Inventroy 100 100 100
Net requirement 0 0 800
Planned receive 900
End Inventory 100 100 100
Planned order 900
4
400
100
4
800
100
900
0
900
900
0
4
400
400
0
400
400
0
4
0
0
0
0
0
0
4
800
800
0
800
900
100
4
0
0
100
0
100