Warehousing Equipment
The role of equipment in warehouse
operations
• Reduce cost (labor + space)
– enhance space utilization by, e.g.,
• enabling the exploitation of the vertical dimension of the facility
• allowing for denser packing
– allow for more efficient operations by, e.g.,
• increasing the sku density
• supporting the automated transfer of material from storage to sorting
and consolidation area
• Enhance responsiveness
– increase the throughput of the facility, e.g.,
• increasing the sku density
• establishing a more ergonomic environment/arrangement for the
warehouse operators
• facilitating the parallelization of order picking
• by parallelizing the tasks of order-picking and replensihment
The role of equipment in warehouse
operations (cont.)
• Maintain Quality of Product and Operations
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provide an orderly storage environment
provide efficient ways for product tracing and identification
provide safe and secure material handling
facilitate order sortation and consolidation
establish and maintain a controlled environment e.g.,
• temperature control
• access control
Equipment Classification
(Tompkins et. al., pgs 170-173)
• Containers & Unitizing Equipment
• Storage and Retrieval Equipment
– Unit Load
– Small Load
• Conveyors
• Warehouse docks and dock-related equipment
• Automatic Identification and Communication Equipment
Pallet Storage Modes
• Block Stacking
• Rack Storage
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Single-Deep
Double-Deep
Drive-In/Through
Pallet Flow
Unit Load AS/RS
etc.
Block Stacking (or Floor Storage)
Lane Height
Lane Depth
(3-deep)
Lanes
An efficient storage mode when
• there are multiple pallets per SKU;
• inventory is turned in large increments, I.e., several loads of the same SKU
are received or withdrawn at one time.
Main problems:
• Loss of space due to “honeycombing”
• not effective utilization of the vertical dimension of the facility
Selective or Single-Deep or Simple
Pallet Rack
• The “benchmark” storage mode
• Due to rack supports, each pallet is independently
accessible (i.e. it supports totally random access)
• Trade-off: too many aisles => inefficient space utilization
Double-deep rack
• Two selective racks placed back-to-back => 2-deep lanes
• Each lane dedicated to one SKU => space loss in case of
SKU’s with odd number of pallets
• Less aisle space required (upto 50% savings in aisle space)
• Trade-off: More work and/or specialized equipment for
retrieving
Other pallet rack types
• Drive-In/Through rack: 5-10 loads deep
– Better space utilization
– More difficult, even dangerous retrieval
• Pallet flow rack: up to 8 pallets deep
– The rack shelves are slanted and have rollers, and therefore, every
time a pallet is retrieved from a lane, the pallet behind it takes its
position.
– Allows for simultaneous picking and restocking
– Supports FIFO operation
– Typically used in high-throughput facilities
• Cantilever rack:
– Supports long items like timber and pipes
Unit-Load Retrieval Equipment
• Key Differentiation factors:
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aisle width requirements
lift height/weight capacity
Lane depth they can reach
degree of automation
capital expense
• Major types
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Walkie Stacker
Counterbalance Lift Truck
Narrow Aisle Vehicles
Automated Storage/Retrieval Machines
Small Load Storage and Retrieval
Equipment
• Operator-to-Stock (or Man-to-Part or in-the-aisle) system:
the operator travels to the storage location to retrieve
material
• Stock-to-Operator (or Part-to-Man or end-of-aisle) system:
the material is mechanically transported to the operator for
retrieval
• Advantages of STO:
– higher productivity
– easier supervision
– better item security and protection
• Disadvantages of STO:
– more expensive
– more maintenance
– more difficult to reconfigure
Operator-to-Stock Storage Equipment
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Bin Shelving
Modular Storage Drawers in Cabinets
Carton Flow Racks
Mobile Storage
All the above equipment can also be arranged in
mezzanines to get a better exploitation of the building
cube.
Operator-to-Stock Retrieval Equipment
• Picking Cart
• Order Picker Truck (for higher placed loads)
• Person-aboard Automated Storage/Retrieval Machine
– captive aisle
– free roaming
• (Robotic Retrieval)
Stock-to-Operator Equipment
• Carousels
– Horizontal
– Vertical
– Independently Rotating Racks
• Miniload Automated Storage and Retrieval Machine
• Automatic Dispenser
• Productivity gains
– Allow for extensive parallelization of order retrievals
– Focus on extracting rather than traveling and searching
Conveyors
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(Flat) Belt
Roller
Telescoping Belt
Chute
Sorting
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Deflector
Push Diverter
Pop-up Skewed Wheels
Pop-up Roller
Tilt tray
• Remarks:
– Conveyors change the economics of travel.
– They can partition physically the warehouse into zones
Warehouse docks and dock-related
equipment
• Warehouse docks: The facility interface with the shipping
carriers
• Dock configurations and dimensioning
Equipment facilitating the interfacing
between docks and shipping carriers
• Dock levelers: compensate the height difference between
the carrier platform and the dock door
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mobile yard ramps
permanent adjustable dock boards
truck levelers
scissors-type lifting docks
• Bumper pads: absorb the shock from the impact of the
shipping trailer with the dock walls (laminated rubber
cushions)
• 40,000 lb load traveling 4 mph => 150,000 lb force
• Dock shelter: a flexible shield that when engaged to the
carrier provides a closed-environment interface between it
and the inner area of the warehouse
– energy savings, increased safety, product protection, etc.
Automatic Identification and
Communication Equipment
• Permits real-time, nearly flawless data collection and
communication, and therefore, it facilitates and increases
the real-time awareness of the location, amount, origin,
destination and schedule of the material.
Automatic Identification and
Recognition
• Bar coding technology:
– bar codes
– bar code readers
– bar code printers
• Optical character recognition
• Radio Frequency (RF) and Surface Accoustical Wave
(SAW) tags
• Magnetic Stripes
• Machine Vision
Automatic Paperless Communication
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RF data terminal
Voice headset
Light and Computer Aids
Smart card
Closure...
• The College-Industry Council on Material Handling
Education (CICMHE) principles on MH (Askin &
Standridge, pg. 296; Tompkins et. al., pg. 158)
• MHS-related information sources: Tompkins et. al., pgs
280-281
• An interesting site: http://www.mhia.org/et/mhe_tax.htm