Supply Chain Logistics - Product Storage: Notes

Destination and Direction of Unloaded Products

• All materials arriving at a facility have a designated use and must be directed and tracked as they are unloaded, a basic part of the distribution process.
• Materials are sent for a purpose: storage, distribution, or use in the production process.
• Materials are often unloaded and placed in a staging area near the loading dock until the next location is determined.
• Materials are then moved from the loading dock area to a designated location (storage, manufacturing, distribution, or order-picking).

Chapter 2 Overview

• The chapter explains how products are stored and provides an overview of storage types and equipment.
• Front-line workers should understand foundational concepts affecting product storage.
• Storage systems range from simple floor stacking to advanced, automated storage and retrieval systems.

Objectives

1. List methods for determining destination and direction of unloaded materials.
2. Identify key issues affecting how materials are stored.
3. List forms in which materials are stored.
4. List options for storage.
5. Describe a system for automated storage and retrieval.

Key Issues Affecting How Materials are Stored

• Several issues affect how materials are stored, including:
  • Mass, measurement, and space
  • Volume, density, and size (have the greatest impact)
  • Depth, containment, and process
  • Weight, configuration, and delivery

Volume

• How material is stored depends largely on volume, considering:
  • Quantity: How much of any one kind of material is on hand.
  • Throughput (velocity): How much material is retrieved for shipment within a given period.

Density

• Large quantities of an item are likely stored as unit loads (on pallets or in similar large containers).
• The larger the quantity, the more desirable it is to store unit loads in high-density storage arrangements to reduce floor space dedicated to aisles and the size of the storage facility.
• In general, the greater the volume, the greater the desire for high-density storage arrangements.

Location Determination and Tracking

• Delivery locations for incoming materials must be clearly marked or designated, and products/contents must be clearly labeled.
• Materials often arrive just in time to be included in an order to a customer.
• A numbering system (address or locator system) is necessary to add structure and logic to material movement within the facility.
• The precise location for incoming materials is typically determined using a warehouse management system (WMS), a software program that matches materials to a desired destination and tracks movement.

Examples of Material Storage

• Materials from a grocery distribution center (e.g., cans of soup) are likely stored and handled as cases.

Storage Equipment

• Storage equipment suitable for dealing with pallets, boxes, cases, totes, and similar storage units must be available.
• Density is especially important when easy, frequent access to materials is required due to high throughput.

Size

• Size matters mainly when dealing with individual items.
• Pallets, containers, and cartons have fairly standard dimensions.

Summary

• Volume (quantity of materials) dictates how materials are stored and impacts density (storage arrangements) if throughput is not impacted.

Forms in Which Materials are Stored

• Materials are generally stored and shipped in the manner in which they first arrived at the doors of a facility.
• Storage and quantity depend on whether they are pallets, cases/cartons, or individual items.
• Large demands for materials call for unit load retrieval and shipment; as demands and orders decrease in size, the process moves towards retrieval and shipment of cases and eventually individual items.
• Forms of storage are also related to the type of facility and material involved.
  • Materials moved from a manufacturing facility to a distribution center are likely to be moved and then stored, at least initially, as pallet loads.

Terms to Know

• Automated storage/retrieval system (AS/RS): A high-density, rack inventory storage system with vehicles automatically loading and unloading the racks.
• Cantilever rack: A specialized form of rack used for storing long items such as lumber or pipes.
• Double-deep storage (deep-reach): Rack that holds two units deep, one behind the other.
• Drive-in/Drive-through rack: High-density storage system that allows units to be stored several deep; forklifts can drive between and into racks to retrieve items.
• High-density storage: Storage system which allows pallets to be stored more than one unit deep or high.
• Kitting: The process through which individual items are grouped or packaged to create a single shipment.
• Mobile sliding rack: Storage racks that sit on tracks so they can be moved to retrieve items; an aisle can be opened between any two rows to allow access.
• Stacking frame: A device consisting of interlocking units that enables stacking of materials so that crushing does not occur.

Rack

• Bulk stacking is not an option for all materials; the logical alternative for storing such materials is a storage rack.

Bulk Grouping

• To help in retrieval and to facilitate inventory control, large numbers of unit loads of the same SKU or same type of materials are usually stacked on the floor together. This is called bulk stacking.

Height Considerations

• In a facility with lower ceiling heights (e.g., three or fewer stacked pallet loads), floor stacking may be used instead of purchasing a rack or stacking frame.
• In most facilities, floor space is at a premium.
• No storage devices other than the pallet or skid on which materials are unitized are needed.

Considerations for Bulk Stacking

• Important considerations in evaluating the use of bulk stacking are:
  • The stackability of the material
  • Possible damage to the materials by crushing
  • Material rotation – how long the material will be in the location

Mobile Sliding Racks

• Mobile sliding racks consist of rows of storage racks affixed to rails embedded in the floor.
• Workers can move the rows to access several rows of racks using one aisle.

Repack: Shelving, Bin, and Drawer Storage

• The storage and handling of small items (e.g., electronic parts, nuts, bolts, small assemblies) is a frequent task.
• Workers may replenish the order-picking area for item picking or kitting.

Example

• Assembling nuts and bolts for a homeowner product (e.g., a child’s swing set).
• Material handling workers gather these items in larger quantities and place them in a central working area.

Storage Rack Construction

• The storage rack is usually made of formed or structural steel.
• The size and gauge of the steel are determined by the capacity needed to house and support the stored materials.

Selective Pallet Racks

• Pallets of materials are placed in openings in the storage rack and supported by load-supporting beams.
• Selective pallet racks can be used for:
  • Standard single-deep storage using a counterbalanced lift truck.
  • Narrow-aisle storage using a narrow-aisle reach truck.
  • Deep-reach greater than single-deep storage (typically double-deep storage).

Drive In/Drive Through Racks

• Drive-in and drive-through racks are most often used when there is a need to store a large number of pallet loads of the same SKU and there is a limited amount of floor space available for storage equipment.
• They make effective use of floor space and are able to store pallet loads 5-10 pallets deep.

Push-Back Rack

• Pallets (unit loads) are loaded on carts or trays within the rack, which are at a slight incline from front to back.
• Materials are pushed up the incline against other pallets already in the rack.

Cantilever Rack

• This type of storage rack is seen in home centers and facilities that handle and store materials such as lumber, steel sheets and rods and other relatively long or unusually large items.

Shelving, Bin and Drawer Storage

• Ease of movement and assembly make shelving a logical choice for materials that do not need the bulk of structural steel storage racks to house them

Supportability

• Shelves and vertical supports can be joined by nuts and bolts, clips, or by riveting.
• Facilities must consider the gauge thickness of the metal when choosing shelving.
• Shelving supports must be able to handle the weight and size of the load.

Drawer Storage

• Some items may be extremely fragile or valuable.
• These items must be handled and stored in a safe and secure manner.
• Storing these materials or items in drawers is a logical way to organize them and to provide needed security and care for them.

Storage Drawer Systems

• Storage drawer systems usually involve a storage cabinet.
  • A storage cabinet contains multiple drawers that can be locked for security.
  • Storage cabinet drawers can be “lined” with protective fabric or rubber matting to protect the contents against scratching or scoring.

Palletized Storage

Pallet Materials

• Pallets have historically been made of wood, but plastic, paper, rubber, and metal are also used.

- Regardless of construction material, the basic design of a pallet is the same.

• Corrugated paper: Used in some cases to form a lightweight pallet.
• Rubber and plastic: Used where sanitizing and wash-down capabilities are needed.
• Metal: Used to handle extremely heavy loads that other types of pallet materials cannot.

Small Bins

• Small bins placed in shelving or racks at a workstation are generally the way to manage small items
• these bin systems are continually replenished by workers.

Shelving

• Shelving used for storage is commercial grade.
• It is usually made from higher gauge metal than household-type shelving.
  • Shelving is a convenient and cost-effective form of storage.
  • Shelving is easily assembled and placed where needed in the facility.

Terms to Know

• Push-back rack: A high-density storage system that can hold several units deep on slightly inclined rails. As a unit is removed from the front, the incline causes units behind it to move forward into the front location.
• Single-deep storage: Rack that holds only one unit (typically a pallet load) deep.
• Vertical lift module (VLM): Automated storage and retrieval system that moves units or items between levels in a facility.

Pallet Loads

• Not all pallet loads necessarily contain a large quantity of a single material.
• Pallets generally arrive at a facility as full pallets but sometimes depart the facility containing many different items called a mixed pallet load.
• Because pallets are usually more efficient to handle than individual cases, shipments departing a facility for a specific destination often consist of smaller quantities of many different items.
• These items are sometimes combined on a single pallet.

Pallet Pooling

• Some companies practice pallet pooling, in which a large group of companies purchases a pool of pallets that any company in the group may rent.
• When shipping and receiving, these pallets must be tracked and accounted for just like any other material.
• This system makes pallets less of a burden on businesses and is more environmentally responsible.

Choice of Pallet Material

• The decision on what type of material to use in the construction of pallets is made by the users of the pallet.
• There are several considerations involved in deciding which materials are best for a particular use:
  • Durability - including the number of trips that the pallet makes into and out of the facility.
  • Weight-carrying capacity.
  • Special applications such as food service or corrosive environments that require a pallet that can be easily cleaned or sanitized.

Key Issues in Palletizing

• Materials may arrive for storage on a pallet and even be stored temporarily as a pallet load.
• Based on demand, some of the items on a pallet may eventually be shipped as cases or as a single item.
• As a result, a certain number of loads on pallets may be broken apart to provide access to the individual cases.

Specialty Containers

Plastic Totes

• Provide protection and unitizing for materials that enter and leave the facility.

Crates

• A crate is a common term for containers made of wood.
• A wooden crate can be built around almost any item in need of protection.
• It can be a solid wooden wall enclosure or a shell that provides enough structure to enable the object to be grasped and moved while providing a degree of protection at the same time.
• Wood is a cheaper material for pallet and container construction.
• The cost of leaving a wooden device after a single, one-way delivery is smaller in comparison to the alternatives.

Crates for Military Use

• The military ships and stores some rather uncommon materials and objects.
• These materials or objects may not be capable of being housed in conventional containers.
• The military relies heavily on wooden crates as a means of protecting materials for military use.
• The military sometimes ships combustible and/ or explosive items.
• Use of metal containers could cause a problem, especially when shipping ammunition, by emitting sparks from metal shipping or storage enclosures.

Corrugated Paper Pallets and Containers

• Great strides have been made in paper technology in recent years.
• The use of paper and corrugated paper has emerged as a viable form of material for protective packaging.
• An increasing number of storage and unit load devices are being made from paper.
• The corrugated or cardboard box has long been a container of choice for many storage and transportation purposes.
• It is not unusual to see pallets and pallet boxes made from corrugated paper.
• The protection level and unit load formation capabilities that these enclosures provide have been improved by applying special coatings to the paper or by blending in chemical additives as the paper is being made.
• These actions make the containers more resistant to the elements.

Container Variety

• They are available in a wide variety of sizes and shapes.
• Special designs are also readily available from the makers of these containers.
• These containers can house almost any kind of material, including bulk materials and liquids.

Small Plastic Totes

• Small plastic totes can be carried by an individual worker to transport small items or orders from one location to another.
• This is a common use of this type of container.

Metal Containers

• Metal containers are a typical protective and unit load formation device used in manufacturing and logistics facilities.
• Metal is strong, durable and affords a high degree of protection against abuse.

Metal Container Variety

• Metal containers are available in a wide variety of shapes, sizes, and features.
• Metal containers that have solid side-walls made from corrugated steel are very common.

Wire Mesh Containers

• Another useful form of metal container is a welded wire mesh container.
• It has many features of the plastic tote.
• It can be made to fold or collapse unto itself for ease and efficiency of storage when not in use.

Other Methods of Storage and Retrieval

Carousels

• A carousel is a type of powered storage device that moves either horizontally or vertically.
• Storage bins are brought to workers who may be either placing items into or retrieving them from storage.

Horizontal Carousels

• Horizontal carousels move on a horizontal plane.
• The items are stored in baskets or shelves on the carousel.

Vertical Carousels

• A vertical carousel moves shelves and bins of materials in an upward and downward circular motion.
• Vertical carousels resemble a dumb waiter.
• This unit is usually self-contained.

Vertical Carousel Enclosures

• All of the motions take place in an enclosure.
• The desired materials are brought to an opening in the cabinets for storage and retrieval.
• An enclosed vertical carousel is often the equipment of choice if security and ease of access are equally important.

Paper Container Treatments

• Insulation for package contents is provided with the addition of interior packaging materials.
• Extremes of cold are not often a problem, but heat can present a problem for paper containers for obvious reasons.
• Chemical additives and coatings can make these containers less susceptible to heat and resistant to fire.

Slip Sheets

• Slip sheets are used to ship materials without the bulk and weight of pallets.
• They are usually made of corrugated material and fit between stacks of containers.
• They may require transfer to a standard pallet on receipt of the materials using a specially equipped lift truck.

Drums and Barrels

• Bulk materials such as powdered goods and liquids are often contained in drums and barrels and can be especially unique in their application in a facility.

Function

• Are usually used to transport and store liquids and powdered or granulated goods in bulk
• Can be metal, plastic or wooden
• Require lift trucks to use special attachments

Power of Pallet Pooling

• The concept of using/sharing/reusing pallets is notable.
• Called pallet pooling, this circular loop manages pallets and makes them available for use across many companies and industries.

Benefits of Pallet Pooling

1. Reduce operational costs - no capital outlay for one-way pallets or shipping platforms.
2. Gain greater budget flexibility: pay for what is needed, when it’s needed
3. Solve materials handling requirements with access to advice from industry experts.
4. Meet supply needs during times of seasonal or unexpected spikes as equipment is available on-demand.
5. Reduce staff costs with no pallet procurement or disposal programs to manage.
6. Reduce environmental impact with reusable packaging.
7. Save on storage costs by holding less pallet inventory - companies can collect and return pallets to CHEP at any time.

Flow Rack

• A flow rack moves boxes, totes or pallets on gravity rollers or skate wheels from the rear to the front of the rack.
• Materials are loaded at the back end and retrieved at the front.
• As materials are removed from the lower end, the remaining materials roll forward.
• These types of racks offer a higher density of storage, require fewer access aisles and use less floor space than traditional pallet racks.

A-Frame Dispensing System

• An A-frame dispensing system handles individual items that material handlers pick from unit loads.
• As the name implies, workers literally open cases or cartons of materials and dispense items out.
• These items are placed in the appropriate slots in the walls of the device.
• A control system tells the slots to release the item onto the belt, picking the desired items to fulfill an order.
• This process is very similar to the candy dispensing machines seen in break rooms and the halls of hotels and motels but is more highly automated in its operation.

Mezzanine

• A mezzanine is a structure built over the top of the other activities in a facility that creates another floor for facility workers to use.
• It makes use of the unoccupied space that exists over all the other activities going on below.
• The mezzanine is a relatively inexpensive way to provide additional space for storage, offices or high-security areas.
• Shipping and receiving dock areas are often designed with mezzanines because the area above docks is not typically used for high volume storage.
• Where travel is permitted under the mezzanine, shelving and bin storage can be built below the mezzanine, creating more space for needed storage.

Automated Storage and Retrieval Systems (AS/RS)

High Tech

• AS/RS are storage and retrieval systems that are different from carousels and VLMs.
• They tend to be large and use extensive banks of racks to store items.
• Storage/retrieval machines such as cranes in the center aisle of the AS/RS or shuttles in various storage lanes move items into and out of these systems.
• AS/RS are designed to store both large and small items such as pallet loads or smaller unit loads of materials.

Automation

• All AS/RS are automated to varying degrees.
• Some are so automated that they can store and retrieve materials without direct human involvement.
• Commands are given to them through computer programs.

Man-on-Board AS/RS

• The most basic AS/RS used to store and retrieve materials is the man-on-board.
• This system has an operator who rides along with an order-picker and its load.
• The man-on-board AS/RS is used for in-aisle picking.
• The machine can be manually or automatically controlled, but there is an operator present on the machine itself.

Fully Automated Storage and Retrieval Systems

• These systems consist of an integrated computer-controlled system that combines:
  • The storage medium (rack or shelving)
  • Transport mechanism (the crane or shuttle)
  • Controls with various levels of automation for fast, accurate and random storage and retrieval of products and materials

Storage/Retrieval Machine Operation

• The storage/retrieval machine of an AS/RS operates in a narrow aisle in the center of the system, and serves rack openings on both sides of the aisle.
• It can travel horizontally (along the aisle) and vertically (up and down a rack) at the same time.
• Because the aisles in this type of operation are very narrow, the equipment is usually either wire-guided or guided by rails that are built into the floor.

WMS and storage locations.

• WMS software is used because there are many questions to be answered when determining storage locations:
  • Does the material need to be co-located with other materials that are usually ordered together?
  • Does the material need to be stored in a unified form, such as a pallet, which can later be broken down and stored in smaller quantities?
  • Does the material have environmental considerations such as protection from extreme temperatures or moisture?
  • Does the material require biohazard or other safety considerations?
  • Does the material need special packaging?
  • Does the material need rack or bulk storage?
  • Does the material have a shelf life?

Vertical Lift Modules (VLMs)

• These are a type of storage equipment that uses both vertical and horizontal areas of a facility in an efficient manner.
• VLMs resemble a dumb waiter that was seen in many multi-story homes of the past.
• The principle of moving things from one floor of a home to the other underlies the concept of the VLMs.

Functions Compared

• VLMs are very similar to carousels in their abilities but VLMs are capable of a higher volume of throughput than both vertical and horizontal carousels.

Accessibility

• VLMs are used when access to stored materials is needed at different levels or floors.
• These pieces of storage equipment can be designed so that the openings are accessible to workers at different levels of the facility.

Sophisticated System Advantages

• There are advantages to this sophisticated system:
  • Fewer material handlers are needed
  • Better material control (including security)
  • More efficient use of storage space
  • Higher throughputs of materials or items.