Warehousing Equipment – Tompkins et al., “Facilities Planning”, John Wiley & Sons, 1996: Chapters 6, 9 – College-Industry Council on Material Handling Education: Material Handling Equipment Taxonomy: http://www.mhia.org/et/mhe_tax.htm
Jan 16, 2016
Warehousing Equipment
– Tompkins et al., “Facilities Planning”, John Wiley & Sons, 1996: Chapters 6, 9
– College-Industry Council on Material Handling Education: Material Handling Equipment Taxonomy: http://www.mhia.org/et/mhe_tax.htm
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 order-picking 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– 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
For detailed functional descriptions, discussion on supported efficiencies,
and pictures
– College-Industry Council on Material Handling Education: Material Handling Equipment Taxonomy: http://www.mhia.org/et/mhe_tax.htm
– Tompkins et al., “Facilities Planning”, John Wiley & Sons, 1996: Chapters 6, 9
Pallet Storage Modes
• Block Stacking
• Rack Storage– Single-Deep
– Double-Deep
– Drive-In/Through
– Pallet Flow
– Unit Load AS/RS
– etc.
Block Stacking (or Floor Storage)
Lanes
Lane Depth(3-deep)
Lane Height
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multiple pallets per SKU;• inventory is turned in large increments, I.e., several loads of the same SKU are received or withdrawn at one time.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:
– aisle width requirements
– lift height/weight capacity
– Lane depth they can reach
– degree of automation
– capital expense
• Major types– 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
• 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
• (Flat) Belt
• Roller
• Telescoping Belt
• Chute
• Sorting– 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– 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
• RF data terminal
• Voice headset
• Light and Computer Aids
• Smart card