Introduction to Storage Systems

Storage Systems, simply refers to the system in which the cargoes are being stored in the warehouse.

A well-designed storage system should:

• Make good use of building volume, by choice of appropriate storage system, careful layout, minimising aisle widths and using headroom;
• Provide good access to stored goods, minimise travel distance and facilitate throughput of goods;
• Incorporate systems such as stock records and locations, and stock movement control and replenishment;
• Provide security against fire, damage and theft; and
• Provide an environment to prevent deterioration or contamination of stock.

In addition, the choice of storage medium for a particular application will depend on:

• Physical characteristics of goods stocked, such as weight, shape, size, strength, package, unit load weight, height, etc.;
• Hazard factor, such as fire, noxious gases;
• Value of the goods;
• Stocks and throughput levels;
• Contamination risks, regarding odours;
• Characteristics of the available storage methods and equipments;
• Number of line items;
• Capital availability; and
• Deterioration factors, considering product life.

Palletised Storage: Block Stacking

In Block Stacking, loaded pallets are placed directly onto the floor and built up in stacks, in rows. Ideally, any one row of pallets should only contain pallets of the same products to avoid double handling and to simplify stock location records.

The block stacking technique is used with plain palletised loads, pallet converters and similar load protection devices that are used if the load itself is not strong enough or flat enough to permit safe stacking.

When setting out simple block stacking, clearances should incorporate to facilitate fork truck movement. It is good practice to empty a row completely before putting any more stock into that row, and it is important to maintain stock location records to ensure stock discipline.

The technique is suitable where there is limited number of product lines, each of which has a comparatively high stock level.

The advantages of Block Stacking are:

• Lower capital costs;
• No storage equipment needed;
• Good use of area though not necessarily of height;
• Simple to control; and
• Suitable for high throughputs.

The disadvantages of Block Stacking are:

• Limits on stack height which can restrict the use of building height;
• Honeycombing which reduces storage capacity;
• No strict FIFO;
• Free access is only to pallets at the top of each row; and
• Fire risk.

Palletised Storage: Adjustable Pallet Racking (APR)

Adjustable Pallet Racking (APR) is the most widely used storage system for all palletised and non-palletised loads. Racking construction consists of end frames and horizontal beams, and the height of the beams can be adjusted to suit the height of pallet loads to be stored.

Single or double-sided runs of racking are separated by aisles that can be sized to suit the customer’s forklift trucks. The basic design of APR is for flat pallets, but accessories are available for storing particular unit loads, such as drum stoppers, decking, and channel supports.

The advantages of APR are:

• High accessibility to all pallets;
• Designed to suit all load sizes and available space;
• Use of standard forklift trucks;
• Easily installed and repositioned;
• High occupancy rates; and
• Cost-effective.

The disadvantages of APR are:

• Fork truck aisle gives access to only two rows of racking, hence, the building space utilisation is low; and
• For racking heights above 8 m, a chemically treated flat floor is needed to stabilise the racking with the load.

Palletised Storage: Double Deep Pallet Racking

The Double Deep Pallet Racking is constructed to store 2 pallets deep or 4 pallets deep in double entry rack, used ideally when multiple pallet quantities of each product are stored.

A derivative to the selective pallet racking, the double deep system requires the use of a specialist reach truck or an attachment fitted to reach truck. Whilst achieving increases in capacity of up to 30% above the former, only 50% of the pallets are immediately accessible.

This system, however, provides an excellent method of increasing warehouse capacity or when alternative systems, such as the Drive-in Racking, which require high numbers of homogenous pallet types, are not possible.

The advantages of Double Deep Pallet Racking are:

• Increased storage density; and
• Highly spaced-efficient storage system.

The disadvantages of Double Deep Pallet Racking are:

• Requires specialised forklifts like the double reach trucks;
• Speed of access to all of the pallet positions is restricted;
• Loss of absolute FIFO; and
• Poor visibility for the truck drivers when accessing the rear locations.

Palletised Storage: Drive-in and Drive-through Racking

Drive-in and Drive-through Racking is used for high-density storage in a given area to increase capacity by some 60-80% over conventional ‘aisle’ racking.

It is frequently used in facilities with a low number of product lines. This racking has veritical support frames, ties at the top, with cantilever pallet support beams at different heights. Pallets are stored in a block system with a reduced number of aisles.

Forklifts drive into the racking to load or retrieve pallets, which are stored on cantilevered rails running throughout the system. If the access into the racking is from one end, the term “drive-in” is used. Racking assessed from either end is called “drive-through”. Racking heights are up to 10 m, allowing the full height and floor area of the building to be used to provide maximum cubic storage space.

The advantages of Drive-in and Drive-through Racking are:

• High-density storage allowing a greater number of pallets to be stored per cubic metre than other storage systems;
• Ideal for batches of pallets;
• Suitable for seasonal goods and fluctuating stock demand;
• Ideal for cold and chill storage and bulk storage applications;
• Suitable for fragile loads, which cannot be block stacked;
• Low capital cost and no special handling equipment required; and
• Continuous racking up to 10 m high without aisles.

Palletised Storage: Live Storage

The need to remain competitive in an increasingly challenging marketplace is a challenge faced by all companies.

Efficiency savings need to be generated constantly to remain ahead of the competition. Whether it be savings in material cost or reduced labour cost resulting from more efficient working practices, the challenge to reduce cost is evident throughout the organisation.

Within the warehouse environment, order picking is the most labour intensive operation. This makes it the ideal place to look at optimising the operation, in order to achieve the required efficiency savings. The key lies in eliminating the unproductive time within the warehouse, which reduce the picking rates of each operator.

The Live Storage system is designed to provide:

1. Shortest picking route;
2. Quicker identification of product and verification against order documentation ;
3. Faster picking of items;
4. Eliminatation of congestion and delays when picking and replenishing staff operate in the same aisle;
5. Guaranteed FIFO stock rotation; and
6. Reduced operator fatigue due to poor ergonomic pick face.

The advantages of Live Storage system are:

• Improved productivity – more picks per day from each operator;
• Reduced labour cost – less people required to complete the same work; and
• Rapid return on investment.

Palletised Storage: Powered Mobile Storage

The Powered Mobile Storage system makes storage more accessible. Easy hands free, one-touch system starts and stops carriage movement. Automatically activated infrared safety systems do not require special training. Space for only one aisle is needed for fork trucks access, and the racks are moved to open up an aisle as required for access to specific pallet locations. The layout usually consists of a number of mobile sections working between fixed end racks. Moreover, control of movement is important to reduce queuing if a number of fork trucks are working at the racking at the same time.

The advantage of Powered Mobile Storage system are:

• 100% greater storage capacity or 50% space reduction;
• Specific system configuration can be provided to meet customers' needs;
• Good space utilisation;
• Random access to every pallet; and
• Suitable for stock, which does not move very fast - where the number of line items is high but frequency of accessions per line is low.

The disadvantages of Powered Mobile Storage system are:

• Expensive to implement; and
• Floor loadings are high, probably requiring reinforcement.

Palletised Storage: High Rack Narrow Aisle Racking

High Rack Narrow Aisle Racking makes optimum use of floor area and roof height while at the same time providing high density storage with 100% accessibility and good stock rotation. The system is served by specialised high lift fork rotating materials handling devices operating in very narrow aisles. The benefit being up to 50% saving in aisle width when compared to a counter balance forklift, whilst achieving up to double the stacking height.

As the fork lift is guided within the aisles, the risk of damage is minimised, resulting in lower maintenance. Very flat floors, close tolerance racking, carefully located pallets of uniform size and stock location systems are all prerequisites for successful narrow aisle systems. Floor guidance in the aisles is mandatory and the design interface between all aspects of their systems is needed. Truck lift height of 14 metres with man up capability is available.

The advantages of High Rack Narrow Aisle Racking are:

• Floor mounted free roaming trucks as flexible in multi aisles;
• High speed throughput with specialised equipment;
• Controlled materials handling provides safe and damage-free environment;
• Fire suppression; and
• High average locations used of 95%, 100% accessibility, good stock rotation and 50% floor utilisation with high cube available.

Palletised Storage: High Bay

'High bay' warehousing describes pallet racking up to heights of 30 - 35 m, in which the pallet movements is by means of stacker cranes, giving free access to all pallet locations. Aisle widths can be narrow as load plus side clearances. Because of the height, conventional APR is not generally strong enough to carry the imposed loads so structural steel is usually adopted. The racking structure may then be used to support the walls and roof of the building, that is, it becomes the building structure, hence the terms 'roof-on rack' and 'clad rack'. Because pallets are accessed by a stacker crane running on floor-mounted rails, the floor surface and flatness are not critical, although floor strength clearly is.

The advantages of High Bay warehousing are:

• Space utilisation is high- the use of height and narrow access aisles; and
• Stacker cranes, which can move very quickly, can be manually or automatically controlled, hence they are very suitable for automated warehouses.

The disadvantages of High Bay warehousing are:

• Special fire sprinkler systems may be required;
• High bay storage systems are expensive to build; and
• Little flexibility for subsequent change, thus design should be carefully based.

Small Item Storage

For small item storage systems, it should be modular to allow different storage components to be grouped, be sub-divisible to allow for different sized stock items, incorporate facilities for product and location identification, and minimise the manual effort in lifting and handling. Some small parts storage systems, such as Shelving, Tote Pans, Louvre Panel Systems and Plastic Bins, Cabinets and Drawer Units and Mechanised Systems are described in subsequent posts.

Small Item Storage: Shelving

Shelving comes in standard component sizes, to various heights, vertical shelf spacing and shelf depth, with ‘short span’ shelving that is usually 1 meter wide and ‘long span’ shelving of 3 meters or more. However, due to the different constraints in warehouses, shelving can be customised to fit specific requirements. There is a range of shelving, for instance,

Double Entry Tire Rack

The Double Entry Tire Rack is a type of Automotive Shelving
that is specifically designed for auto parts stores.
Product Dimensions (W x D x H):
60” x 42” x 84” with 3 beam levels that can hold approximately 48 tires.

Shelving with Open Frames

The Shelving with Open Frames is suited for the applications

where ventilation is required.
Product Dimensions (W x D x H):
36” x 12” x 87”with 329 kg capacity per shelf.

Boltless Shelving

The Boltless Shelving is also known as rivet shelving,
which is great for just about any bulky product that is hand loaded.

Product Dimensions (W x D x H):
96” x 18” x 84” with 4 levels with 1,000 lbs capacity per shelf.

Metro Wire Shelving

The Metro Wire Shelving is great for
food industry, labs, and even electronics.
Product Dimensions (W x D x H):

36” x 18” x 63” with 4 adjustable shelves.

Record Storage Shelving

The Record Storage Shelving is sized to
efficiently store standard boxes for archived records.
Product Dimensions (W x D x H):

42” x 30” x 99” with 5 shelves that can hold 60 1ft3 boxes including top shelf.

Multi-tier Shelving

The Multi-tier Shelving are shelving installed at multiple levels that allows economical use of cubic space, can accommodate a range of storage requirement, is ideal for archive storage and manual order picking applications.

With Multi-tier Shelving, the upper levels can be accessed with the incorporation of additional storage floors suspended from the shelving structure with walkways to allow pedestrian access for order picking, or by using fixed path trucks or order picking cranes.

The advantages of Shelving are:

• Comparatively inexpensive;
• Gives random access to stock; and
• Modular, interchangeable and is easily moved.

The disadvantages of Shelving are:

• Adjustment to shelf heights is not always easy after a period in use; and
• Separation of small quantities can restrict access, example, hand access between vertical shelf partitions spaced 50 mm apart is limited.

Although the range of shelving mentioned above have their advantages, in my opinion, I would prefer the Mobile Shelving System. I have found videos to illustrate the benefits of it.

Mobile Shelving System

By making use of the Mobile Shelving System, it can effectively save space as it eliminates the need for several access aisles. Due to the fact that the shelving moves along floor tracks, the space for only one aisle is needed. When an item is required, the particular shelving bay is identified and an adjacent aisle is created by moving the mobile units apart. Mobile shelving is opened and closed by either hand operated pull handles, hand wheel driven mechanical systems or electrically operated using small electric motors with push button control.

Additional benefits of this system include the efficient location of items and security - mobile units can be closed and locked together to prevent unauthorised access. Roller racking or mobile racking provides much more efficient space utilisation compared to static shelving or conventional filing solutions such as cabinets and cupboards. As well as saving space, mobile storage systems are ideal where sensitive or expensive items are stored because the shelving can be closed up and locked to restrict access.

Small Item Storage: Tote Pans

The Tote Pan system is an economical system for handling and storing small parts and components comprising individual tote pans and a range of trucks and racks to support their handling and storage. Normally, totes are produced in modular sizes of standard dimensions, are able to nest or stack, incorporate label holders and sub-dividers, and can be fitted to Louvre Panels.

There are various designs of tote made from different type of materials, for instance,

Galvanised Steel Tote Pans

The standard, universal stacking Galvanised Steel Tote Pans are strongly constructed with reinforced rims, easy grip handles and a cardholder at each end. It is a complete, inexpensive system widely used for the handling and storage of components. Furthermore, each galvanized steel tote pan is resistant to heat and oil; will not burn or give off toxic smoke and has the capacity of 30 kg. As optional extras, these tote pans can have coloured ends, be embossed with the company name and can come with dividers, individual part pans, slide-on lids and perforated bases.

Plastic Tote Pans

These liquid-tight; easy to clean standard stacking Plastic Tote Pans with integral handles and cardholder have been developed for general industrial use in storage and handling. Each plastic tote pan has the capacity of 30 kg.

Wire Mesh Tote Baskets

Made in 25mm or 12mm, these Wire Mesh Tote Baskets can be zinc plated or white plastic coated and are able to inter-stack with Tote Pans and fit racking. The advantage of these is that it provides instant stock visibility. Each wire mesh tote basket has the capacity of 25 kg.

Small Item Storage: Plastic Bins and Louvre Panel Systems

Plastic Bins

Plastic Bins are ideal to store small fiddly components in a neat orderly manner. Not only are they available in wide range of sizes but colours as well, which can be used for colour code classification for quick product identification, and can be stacked on top of one another or fitted to Louvre Panels. Bin fronts are angled for easy picking access and have space to insert labels. Side-to-Side or back-to-front dividers are also available as accessories.

Louvre Panel Systems

A Louvre Panel is a versatile addition to the workspace, which can be easily fitted to existing walls or similar structures, or mounted onto trolleys for movement. It is designed to accommodate most industry standard plastic storage bins, tote pans, and also other attachments for more awkwardly shaped items such as vee belts, tool holders, etc, using spigots.

Generally, Louver Panels can be classified into wall mounted, trolley or rack format:

Vertical Wall Mounted Louvre

Horizontal Wall Mounted Louvre

1,600mm High Louvre Trolley

Louvre Panel Rack

The advantages of Louvre Panels Systems are:

• Maximises available space;
• Frees congested floor space; and
• Improves efficiency.

Small Item Storage: Cabinets and Drawer Units

Cabinets and Drawer Units can be freestanding or integrated into shelving modules, and are available in different sizes, dimensions as well as materials. They are compact, helps to optimize space and allow easy access to items retrieval in a clean, tidy and secure way. They can also be fitted with sub-dividers and special inserts for protecting delicate items.

Following are some examples of the various types of cabinets and drawer units:

Modular Drawer Units

All-welded steel Modular Drawer Units have an attractive refined appearance and a heavy-duty construction. The super strong, 400 lbs capacity drawers lock with central cylinder locks and open easily on side mounted tracks. Full-access modular drawers maximise storage space with full height sides and feature full width handles for better grip and a flush, catch-free front. Sturdy modular drawer units have a reinforced base, are stackable, permit forklift access with a 2” front opening and feature a durable baked enamel finish. Drawers include knockouts for ganging and stacking and an anchoring kit for concrete floors and stacking.

Plastic Drawer Cabinet with Steel Frame

The small parts Plastic Drawer Cabinet with Steel Frame easily mounts to the wall or sits atop workbenches (on non-skid rubber pads) for convenient storage. Steel cabinet features welded shelves to ensure maximum stability. Transparent 5-7/8"D plastic drawers are virtually unbreakable. Drawers include a front lip and glides for easy pullout, and spill-preventing stops. These drawer storage cabinets feature a long lasting blue electrostatic powder painted finish with smooth edges for safety. Metal drawer cabinet measures 12"W x 6"D x 22"H.

Drawers with Sub-Dividers

High impact polystyrene Drawers with Sub-Dividers won't rust or corrode and are easy-to-clean. Built-in drawer stops help prevent accidental spills caused by drawer pull-out. Plastic drawers include a label front for quick identification of contents. Optional plastic dividers allow greater parts separation for organised storage.

Stackable Steel Drawer Cabinet with Literature

This Stackable Steel Drawer Cabinet with Literature is made with heavy gauge all welded steel. Literature organisers provide open, at-a-glance storage for documents and mail, while closed drawer cabinets provide tools, supplies and parts storage. Stacks to create a modular storage system. Can be stacked vertically or ganged side-by-side in any combination.

Small Item Storage: Mechanised Systems (Vertical and Horizontal Carousels)

Vertical Carousel

This is an automated vertical storage device which saves valuable floor space. The vertical construction of carousel can go up to a maximum height of 7 m. The storage shelves are arranged in two rows and are held in special carriers. These are suspended at each end in heavy duty roller chains. The shelves can be designed to carry any type, size and quantity of items. For small items, plastic bins of suitable are used.

The movement of the vertical train of shelves is effected by an electro-mechanical device at the heart of which is a micro-processor based logic circuit. At the press of the particular button, the required shelf traverses the shortest path (either up or down) and stops before a window in front of which is a working table. The operator picks up the item easily. Thus the operator does not have to walk around looking for the desired item. The storage and retrieval operation becomes error-free and fatigue-free. As a further step for automation, the carousel can be interfaced with a computer thus making available additional information like stock position, etc., at the touch of a button.

The advantages of Vertical Carousels are:

• Uses a fraction of floor space used by static shelving, usually around 80 sq ft or around 25% of what static shelving would use;
• Simplicity (high reliability, low requirement for electronic coordination of moving parts);
• High speed in picking multiple parts (machine presents all parts in all order requests in one rotation) - when multiple machines are used in conjunction with software, parts can be picked by one person up to 5 times faster than they could be picked from static shelving by that person;
• High weight capacity - up to around 1500 lbs per carrier;
• Flexibility using different configurations of additional shelves in each carrier and reconfiguring when needed;
• Security (when the door at the workstation is locked, the machine is a sealed box); and
• Better ergonomics (all parts are presented at waist level, minimising back problems).

Horizontal Carousels

In Horizontal Carousels, shelved storage 'baskets' are suspended from a continuous overhead chain, which is driven forward or backwards to bring the required stock to the operator. The horizontal carousel is best used when the customer has low ceilings, light parts, or a distribution operation. When multiple machines are placed in a single group to be operated by one individual, that individual can pick from those machines with very little walking. In a group of 4 machines, there is only 12 ft between the pick faces of all 4 machines (as shown below).

The advantages of Horizontal Carousels:

• Ability to be installed under low ceilings;
• Uses between 40 and 60% of the floor space required by a static shelving system;
• Simplicity (high reliability, low requirement for electronic coordination of moving parts);
• High speed in picking multiple parts (machine presents all parts in all order requests in one rotation). When multiple machines are used in conjunction with software, parts can be picked by one person up to 5 times faster then they could be picked from static shelving by that person;
• High weight capacity - up to around 2500 lbs per wire bin;
• Flexibility using different configurations of additional shelves in each bin; and
• Ergonomics (using software "Golden Zones" the faster moving parts are presented at waist level, minimising back problems).

Odd Size Storage: Long Loads

Long Loads are loads such as carpets, linoleum and engineering materials such as rods, bars and tubes that require special storage and handling.


Cantilever Racking

Items with such odd shapes can be loaded in a horizontal racking but this can involve manual handling of the bars into position.

As seen in the attached pictures, the rods are held horizontally onto the racks. This is using the cantilever principle that stacks the rods at different levels. Mechanical handling is usually by means of side-loaders, four directional reach trucks or overhead cranes, which enable access without requiring especially wide aisles.

Pigeonhole Racking

Pigeonhole Racking (as shown above) gives good protection and good access to the stock. The gangway area in front of the racking must be wider than the length of the items being stocked, which reduces overall space utilisation. There are also various systems for mechanised storage of long loads.

The advantages of Long Loads system are:

• Easy storage and retrieval;
• Flexibility of design - number and length of arms, inter-arms spacing, height of the rack, etc., can be suitably designed to store any type, size and weight of material;
• For long and small items, storage channel or a panel can be provided;
• Can be made as single-faced or double-faced units; and
• Tie-bar can be provided at the top for extra stability of the system.

Storing of Dangerous Goods (DGs)

Dangerous Goods (DGs) are substances that may be corrosive, flammable, explosive, spontaneously combustible, toxic, oxidising, or water-reactive. These goods can be deadly and can seriously damage property and the environment. Therefore, it is important that they are stored and handled safely.

The area where DGs are stored, a DG warehouse should be:

• Well ventilated and well lit;
• Separated from ignition sources;
• Secured from the public;
• Protected from temperature fluctuations and direct sunlight; and
• Shelving and cupboards should:
  - Be contructed of chemically resistant materials; amd
  - Provide a lip at the front of the shelf.

Also, at the warehouse, secondary containment such as spill trays should be considered for liquid dangerous goods stored outside of a chemical storage cabinet.

For storage of DGs of quantities below a certain level, requirements are less stringent as the risks posed are lower. This means that storage of low level of DGs in the laboratory can exist without the need to purchase an Australian Standard approved cabinet. However, for storage of DGs exceeding the specific quantities, there is a need for consideration to purchase Australian Standard approved shelving or cabinets for their storage.

Storing of Hazardous Chemicals

Storage on Shelves

Hazardous Chemicals should be stored in chemical storage cabinets or laboratory cupboards. For chemicals that are kept on shelves or racks, they are subjected to the following restrictions:

• Shelving must be compatible with the goods stored;

• Shelving systems must be designed to hold the maximum holding capacity of the chemical containers;

• Incompatible chemicals should not be stored together on shelves. Keep a distance of 3 m between them. The space between can be used to store non-hazardous substances;

• Chemical packagings should not be kept on the floor;

• Solid chemicals should preferably be stored on upper shelves above liquid chemicals;

• Secondary containment is essential for large containers (eg. the 20 L waste cubes). It also makes sense to bund any container with capacity of 2.5 L and above. As a priority, all DGs of this size should be bunded;

• Shelves should have raised edges to reduce the likelihood of dislodging;

• The most dangerous chemicals should be stored at easily accessible heights (eg. 1.5 m from the floor);

• Chemicals should not be stored under direct sunlight; and

• Where refrigerated storage is required, do not use domestic refrigerators. Options include intrinsically safe refrigerators or domestic refrigerators that have been made electrically safe by a licensed electrician.

Storage in Cabinets

Each chemical storage cabinet must have a designated personnel responsible for its management. Their duties would include ensuring that:

• Appropriate emergency spill measures are in place;

• Emergency first aid is accessible and in working state;

• The storage location appears on the building manifest and on the annual notification to WorkCover;

• A risk assessment for storage of DGs is completed for the particular storage location; and

• Disposal of old and unwanted chemicals occurs regularly.

Warehouse Labeling

Warehouse Labelings are important for it serve its purpose to inform warehouse personnel where to locate the particular inventory.

Below are some types of warehouse labeling:

Labels holder

Magnetic and self adhesive Label Holders, enables instant identification or labeling of racking and shelving in the warehouse, storeroom or offices. The C Profile of the magnetic and self-adhesive shelf edge label holders allow fast and easy updates of product information.

Ticket holder

Self adhesive and magnetic Ticket Holders with a pull forward front allows easy loading and updates of information. Barcodes can also be scanned without removing the card. Ideal for pallet racking beam, shelf location and general warehouse labeling.

Document Pocket

Industrial Document Pockets with welded edges are ideal when documentation needs to be kept clean, or simply for control of fast moving stock. They can be used on steel cabinets or racking and shelving.

Aisle Markers

End of aisle identification markers are manufactured in two highly visible colours. Available in white and yellow styrene, these robust Aisle Markers can be fixed flush with the end frame or used as flags, to identify bays along the aisles, with 90 degree flange. Markers are supplied pre-drilled in all four corners unless flanged or otherwise requested and can be supplied with the option of self adhesive or magnetic fixing options.

Bay Marker

The highly visibile Bay Markers can be used for clear identification throughout the warehouse. A formed aluminium section with either a magnetic or self-adhesive edge, enables the marker to be easily mounted onto steel racking without drilling. When locations need to be changed, the magnetic markers can simply be lifted and relocated.