There are many types of storage systems. They can be categorised into racking system, shelving system etc...

Block Stacking

In block stacking, no storage racks or supporting structure is needed. This storage system is used for storing large quantities of palletized or boxed products by placing it directly on the floor and put it in stacks (placing the items on top of each other) or in rows (placing the items next to each other). Common use in paper industry, household products and reserve storage area. Items are retrieved on a LIFO (last-in-first-out) basis.

Depending on the weight and stability of the loads, stacks may range from two loads high to a height determined by:

• Acceptable safe limits
• Load stackability
• Load weight
• Pallet condition
• Floor loading restrictions
• Weather (due to corrugated softening in high humidity)
• Vehicle lift height capacity
• Crushability of the loads
• Building clear height

Advantages

• Low capital cost
• No storage equipment needed
• Suitable for high throughput items
• Minimum cost of storage since cube utilisation is high

Disadvantages

• Material accessibility is low since only top of the front stack is accessible
• Limits on stack height (depend on the loads at bottom of a stack to support the imposed weight)
• Vulnerable to fire risk
• No strict FIFO (first- in- first out)

Selecting Racking

The following will have to be considered:

1)Pallet (or for the product being stored):

• size
• type
• construction
• capacity
• security
• stability

2)Handling equipment:

• type
• maximum lifting height
• dimensions/aisle width

3)Storage area:

• dimensions
• type and construction
• floor loading, capacity
• obstructions, exits, stairs, etc.
• floor fixing facilities.

4) Goods:

• type
• frequency of movement and access

5) Safety:

• fire protection requirements
• fire exits

6) Specialist requirements

• equipment
• accessories
• protective
  

Adjustable Pallet Racking (APR)

Wide-Aisle Pallet Racking System

As shown in the diagrams, pallets are placed a minimum of 2.5m wide between each other so as to allow vehicle to drive through for easy loading and unloading. In addition, it also allows a large volume of products to be stored. No specific requirement of any handling equipment. However, a normal forklift truck would not be recommended due to the height restriction. This system is used when the warehouse has a restriction for low-level picking. Besides that, this system could be use when space utilization is not critical as it helps to smooth the flow of goods, ease of loading and unloading and also gives fast throughput.

To let you briefly understand what storage systems is about, think about your home private warehouse, your storeroom. What type of items are you going to store inside your storeroom? How are you going to place the items? Are the items accessible when you want to take it? How often you need to take the items from your storeroom? How long do you need to take an item? What type of storage system are you going to adopt? Just like your storeroom, planning a storage system for a warehouse need to consider much more factors and likewise every decision you made will affect the overall warehouse's operation and definitely the cost incurred.

• Physical characteristics of goods stocked, i.e. size, shape, weight, package, unit load weight.
• Contamination risks, i.e. isolation storage systems and protective packaging are been used.
• Hazardous factors, i.e. require more fire-security measures such as fire walls, advanced sprinkler installations (ESFR sprinklers), smoke detection, water screens, smoke evacuation hatches, smoke screens, sufficient fire hoses and hydrants.
• Deterioration factors.
• Value of the goods.
• Number of line items, e.g. high or low line items.
• Stock and throughput levels, e.g. turnover frequency, incoming and outgoing volumes.
• Capital availability, i.e. setting up a automated storage system or manual storage system.
• Free height of the building, i.e. the combination of various parameters such as price of land, the height of the racks or pallets, the speed at which goods can be handled at higher positions and the extra costs of a higher building.
• Flatness of the floor, i.e. the influence of logistic systems on floor requirements.
• Bearing power of the floors, i.e. able to bear heavy loads.

(From the top to the bottom pictures: dangerous goods; perishable product; ship spare; metal hose; fire security measures)

Characteristics of the available storage methods

Below shows two examples of storage methods on how products can be located and arranged:

Randomized Storage (or floating slot storage)

• Places items in the closest available slot, bin or rack, when it becomes empty.


• Items are retrieved on a first-in, first-out (FIFO) basis.
  

Dedicated Storage (or fixed-slot storage)

• Products are stored in permanent locations


• Three methods can be used to implement this approach:
  i. Part number sequence
  ii. Usage rates
  iii. Activity levels

• It should be strong and durable enough to stand up to the demanding requirements of an industrious production line which could be operating 24hours a day, 7 days a week. In addition, the warehouse should be built to the highest standard using quality materials.
  
• It must be able to eradicate damage inflicted by careless handling, thus reduce costs.
  
• The warehouse must be designed to prevent contact between stored components which might damage one another or both. It should also reduce the damaging impact of pollutants such as dust.
  
• Hold the equipment securely and safely to prevent any damage that could hard the products.
  
• Incorporate specially designed locking features that hold equipment securely and safely or features that keep the system itself stable, such as locable castors.
  
• Allow easy identification of goods once placed in its rack or compartment.
  
• The storage system should be able to improve inventory control and reduce the time it takes to reload or changeover each machine, which means lower downtime and more efficient production line and increased capacity.
  
• Encourage flexibility so as to use different system for different purposes or different sized equipment.
  
• Enhance production flows.
  
• Compact and functional.
  
• It should be designed so as to eliminate damaging effects of static electrucity. Thus, reduce rework efforts and costs. Include elements such as quality conductive tyre castors that provide an electric path to the floor.
  
• It should be designed to be able to accommodate specific design requirements. This is because even two manufacturers with ideal production lines may need different storage specification depending on their working practices. For this reason, it is important to deal with a storage equipment manufacturer with the ability to offer custom designs. Be prepared to listen and understand a customer's specific storage equipment needs.

Our group comment

Choose a system that is balanced in terms of ease of use, functionality, security and logistical benefits and it will provide a pay back for years through improved safety, reduced mishandling, increased efficiency, reduced defects, increase capacity and ultimately high profits.