Warehousing
Function Storage in Transit Inventory
Economic
–
Consolidation & Break Bulk Consolidation Assortment Postponement Stockpiling
–
Reverse Logistics
– – –
Service - Spot Stocking - Full Line Stocking - Product Support - Market Presence
Consolidation & Break Bulk
Reduce Transportation Cost by using warehouse capability to increase shipment economic of scale
Consolidation, warehouse receives materials from number of sources which combined into a large single shipment to a specific destination
Break-Bulk, operator receives a single large shipment and arrange for delivery to multiple destination
Consolidation Plant A
Plant B
Plant C
Consolidation Warehouse
X Y Z
Break-Bulk Customer X
Plant A
Break-Bulk Warehouse
Customer Y
Customer Z
Assortment Reconfigure freight as it flows from origin to destination
Cross Docking
Mixing
Assembly
Cross-Dock Combine inventory from multiple origins into an assortment assortme nt for specific customer Plant A
Plant B
Plant C
Customer X
Distribution Warehouse
Customer Y
Customer Z
Mixing Customer W
A B C D
Plant A
Customer X
A B C D Plant B
Plant C
Transit Mixing Point
Customer Y
Product D
A B C Customer Z
A B
Assembly Procure inventory from multiple multi ple Vendor to support manufacturing operations Ven endo dorr A
Vendor B
Vendor C
Lead Supplier Warehouse
Assy. Plant
10
Postponement Warehouse postpone commitment to final product configuration by completing final packaging, labeling, and light manufacturing
Reduced Risk
Lower Inventory
11
Stockpiling Accommodate seasonal production or demand
Buffer Stock
12
Reverse Logistics Perform physical work related to product recall, reclamation, disposal of overstock and damage inventory
Control
Regular
13
Service Establishing warehouse to service a specific market area
- Spot
Stocking - Full Line Stocking - Product Support - Market Presence
14
Spot Stocking
Spot Stocked in a Local Market Warehouse in Anticipation of Responding to Customer Need During the Critical Sales Period Rather Than Maintaining Inventory in a Warehouse Yearround
Use temporarily Warehouse for Time Limited Period
15
Full Line Stocking Warehouse can provide one-stop shopping capability for goods from multiple manufacturers
Use Permanent Warehouse for Unlimited Time Period
16
Production Support
Stock Inventory to Support Manufacturing Operation
Support Warehouse Containing an Inventory of Processed Materials, Components and Subassembly
17
Market Presence
Respond faster to customer needs
Increase Market Share and Profitability
18
Warehouse Operation The objective is to efficiently receive inventory, possible store it until required by the market, assembly it into complete orders, and initiate movement to customer
Handling
Receiving In Storage Handling Shipping
Storage - Active - Extended
19
Warehouse Ownership
Private
Public
Contract
20
Warehouse Size
Min = SSL
+Q
Max = SSL+T + Q
Flow of Goods in Warehouse
Receiving Holding Picking
Shipping
Flow of Goods in Warehouse Receiving
Receiving
Holding
Holding
Holding
Picking
Picking
Picking
Batch Forming Packaging Shipping
Receiving
Storage Media
Physical Characteristics of Goods in Stock
–
Solid Goods: Stack, Rack, Drawers
Number of items of each product in a customer order
24
Storage Plan Receiving Dock
Low Volume
High Volume
Low Volume
Senator Nur Bahagia@
Shipping Dock
Storage/Retrieval Transport Picker to Product System
1. •
A team of human order pickers, traveling to storage location
Product to Picker System
2. •
•
An automated device, delivering items to stationary order pickers AS/RS
Block Stacking System
Item Retrieval by Trolley y
x
A/R Machine e l s i a e d i
S
Central aisle
Item Storage and Retrieval By AS/RS and Belt Conveyor e l s i a e d i S
Location and Site Criteria
Services
Operating Cost
Faktor Lokasi 1. Pasar Dan Bahan Baku Jasa
Semen
Fragile
Kertas
Berat
Agro Industri
SERVICES
COST
Faktor Lokasi 2. Tangible . Transportasi . Tenaga Kerja . Energi . Tanah . Insentif
. Utilitas . Biaya Konstruksi . Pajak . Bahan Penolong . Dll
Faktor Lokasi 3. Intangible – – – – – – –
Iklim Peraturan Stabilitas Politik Kemudahan Ekspansi Budaya Polusi Dll
Tahapan Pemilihan Lokasi Regional
Makro Community
Mikro Site
Metoda Pemilihan
Gravitasi BEP Transportasi Point Rating Simulasi
Metoda Gravitasi
Minimasi Ongkos Transportasi
Faktor Faktor Lain Tetap (Sama Untuk Semua Pilihan Lokasi)
Menggunakan Koordinat Cartesian Sebagai Basis
Formula Metoda Gravitasi
J = Ti Bi Ji / Ti Bi Dimana:
Ti : Biaya Transport Dari Tiap Titik i Ke Lokasi (Rp/satuan /Km)
Bi : Berat Yang Diangkut Dari / Ke Lokasi i Ji : Koordinat Dari Titik i
Contoh Metoda Gravitasi Data pasar – A : 10 ton; 5000/ton/km – B : 2 ton; 8000/ton/km – C : 8 ton ; 4000/ton/km Koordinat: –
A (13, 22) ; B (95,84) ; C (118,41)
Contoh Metoda Gravitasi
Jx = (5x10x13) + ( 8x2x95) + ( 4x8x118) (5x10) + ( 8x2) + ( 4x8) = 91,3 KM
JY = (5x10x22) + ( 8x2x84) + ( 4x8x41) (5x10) + ( 8x2) + ( 4x8) = 38,3 KM
Metoda BEP Faktor Yang Lain Tetap ( Sama ) Fix Cost Dan Variable Cost Berbeda
• •
A B
Metoda BEP Total Cost Lokasi A = Total Cost Lokasi B FA + Q. VA = FB + Q.VB
Q = (FA - FB )/ (VB - VA )
Metoda Transportasi
Multi Lokasi
Faktor Lain Sama Kecuali Ongkos Transport
Metoda Point Rating
Menggabungkan Faktor Tangible & Faktor Intangible
Menggunakan Pendekatan Kwalitatif Dan Kwantitatif
Prosedur
Identifikasikan Faktor Yang Relevan Tentukan Bobot Setiap Faktor Tentukan Rating Faktor Pada Setiap Lokasi Hitung Bobot Score Pada Setiap Lokasi Untuk Setiap Faktor Jumlahkan Bobot Skor Pada Setiap Lokasi Pilih Lokasi Yang Memiliki Skor Tertinggi
Contoh
Warehouse Design Criteria
Services
Cost
Warehouse Cost Receiving Cost Holding Inventory Cost Retrieving Cost Assembling to customer order Cost Shipping Cost
Factors To Be Considered Physical characteristics of products Number of items in stock Rate of storage and retrieval request
Warehouse Design 1. 2.
3. 4.
Determining the capacity: length, width and height Locating and sizing: receiving, shipping and storage zones (including number of I/O port, number, length and width of the aisles of storage zone and the orientation of stack/racks/drawers) Selecting the storage medium Selecting the storage/retrieval transport mechanism
50
Basic Warehouse Design Receiving Area Bulk Storage Area
Rack Storage Area
Order Picking Area
Packaging or Unitizing Area
Staging Area Senator Nur Bahagia@
Selecting The Storage/Retrieval
Physical Characteristics of goods Packaging at the arrival Composition of out going lots
Stack
Rack
Drawers
Sizing Receiving &Shipping The Number of Truck Dock ND = [dt/QT] ND d t Q T
: Number of Dock Truck : Daily demand from all order : Average time required to load/unload a truck : Truck Capacity : Daily time available to load/unload a truck
Example Average daily demand is 27.000 units, outgoing shipment are performed by trucks, with capacity equal to 850 units. Average time to load a truck is 280 minutes and 15 working hours are available every day
Number of dock truck: ND = [d.t/Q.T] ND = [27.000x280/850x(15x60)] ND = 10
Storage Policy 1. Dedicated Storage policy: – –
Product is assigned at pre-established set position Easy to implement but causes an under utilization
2. Random Storage policy: –
Product allocation is decided dynamically on the basis of:
–
Current warehouse occupation Future arrival and request-forecast
Allow a higher utilization of space but requires:
Each item be automatically identified Update database of current position of all items
Storage Policy 3. Class Based Storage policy: – Product are divided into a number of categories according to their demand – Each category is associated with asset of zones where the goods are stored according to random storage policy
Sizing of Storage Area
Dedicated Storage policy: n
MD = ∑ max I j(t) j=1
MD : Number of required storage location
I j(t) : Inventory level of item j at time t n
: Number of item
Random Storage policy: Mr = max∑ I j(t) ≤ MD
Example of Storage Area Product A B
Lot 500 200
Safety Stock 100 80
Dedicated Storage policy: MD = ∑ max Ij(t) = 600 +280 = 880
Random Storage policy: Mr = max∑ Ij(t) ≤ MD = 600 + 180 = 780
Length and Width of Storage Length: Lx = ( ax + ½ wx )nx Width : Ly = ( ay ny + wy )
Dimana: ax : Occupation of a unit load along the direction of x ay : Occupation of a unit load along the direction of y wx: Width of side aisle along the direction of x wy: Width of side aisle along the direction of y nx: number of storage location along the direction of x ny: number of storage location along the direction of y
A Traditional Storage Zone
W x
Ly
W y
Lx
Model of Sizing The Storage Zone Minimize: 1 n x y n y wy x w x 2 v 2v
Subject to: n x n y n z m n x n y 0 ,integer
Determining nx and ny
Number of Storage Location Along Y Direction n' y
2 m x 12 w x
y n z
Number of Storage Location Along X Direction
n' x
n x
m y
2n z x 12 w x
n' x
and
n y
n' y
Example Berapa ukuran luas gudang untuk menampung produk A dan B diatas jika: 1. Jika setiap pallet produk A dan B memiliki dimensi yang sama dan memerlukan 1.05x1.05 m2 area. 2. Barang akan diletakkan diatas rak dimana setiap raknya terdiri atas 4 tingkat. 3. Lebar gang utama adalah 4 m dan gang lainnya 3,5 m 4. Cara penempatan barang dengan menggunakan random policy
Example n' x n' y
780 1.05 2 4 1.05
3.5 2
2 780 1.05 1.05 4
6.05
3.5 2
32.25
Example •
nx = 6 and ny = 33
•
Length:
Lx = ( ax + ½ wx )nx = ( 1.05 +(3.5/2))x6 = 16.8 m
•
Width :
Ly = ( ay nx + wy ) = (1.05x33+4) = 39.65 m
Case
Suatu sistem logistik terdiri atas satu unit produksi, satu depot dan 10 agen. Unit produksi berkapasitas 100.000 unit per tahun, ongkos set up sebesar Rp.25.000.000/set up dan ongkos simpan pada eselon produksi sebesar Rp. 20.000/unit/tahun, waktu pengiriman barang dari unit produksi ke depot 1 bulan sedangkan dari depot ke rertailer ditunjukkan pada tabel berikut. Ongkos pemesanan dari depot ke unit produksi sebesar Rp 1000.000/pesan, dan ongkos transport dari unit produksi ke depot sebesar Rp. 50.000/unit, sedangkan ongkos simpan pada eselon depot sebesar Rp.40.000/unit/tahun. Adapun data pada agen ditunjukkan pada tabel berikut
Data Pada Agen Agen j
A j
H j
B j
Rp/Psn Rp/unit/thn Rp/unit
D j
S j
Ldj
unit/thn
unit/thn
thn
Cdj Rp/unit
1
50000
4000
50000
5000
500
0.05
9500
2
40000
6000
50000
4000
400
0.03
8000
3
30000
8000
35000
4500
500
0.10
9000
4
60000
10000
40000
5000
500
0.10
8000
5
75000
12000
40000
6000
600
0.05
6000
6
65000
8000
30000
5500
550
0.05
6000
7
70000
10000
40000
6000
600
0.10
9000
8
60000
8000
45000
5000
500
0.05
6000
9
55000
12000
50000
4000
400
0.05
6000
10
70000
8000
40000
5000
500
0.03
5000
