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multiple pallets per SKU;• inventory is turned in large increments, I.e., several loads of the same SKU are received or withdrawn at one time.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