Storage and handling systems (non-palletized)

INTRODUCTION

Although pallets are very widely used in warehouse operations, there are many types of product that are not suitable for palletization, because they may be, for example, too small, too large or too long, or because they require lifting from the top. These products may include, for example:

•      nuts and bolts

•      electronic items

•      paper reels

•      machinery

•      steel bars

•      carpets

•      drums

•      hanging garments

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SMALL ITEM STORAGE SYSTEMS

Shelving - short and long span, Shelving is generally made from standard modular components that allow installations of different heights, vertical shelf spacing and shelf depths. The typical standard span width is 1 metre, but long span shelving is also available that facilitates the  holding  of  longer  items  of stock

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SMALL ITEM STORAGE SYSTEMS

Shelving - short and long span, Shelving is generally made from standard modular components that allow installations of different heights, vertical shelf spacing and shelf depths. The typical standard span width is 1 metre, but long span shelving is also available that facilitates the  holding  of  longer  items  of stock

Bins, Tote bins are made in a range of materials such as galvanized steel, polypropylene, wire mesh and fibreboard. They are made in modular sizes that are sub-multiples of standard dimensions, and this facilitates nesting and stacking, and the use of different sizes of tote within one installation

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Drawer units, Drawer units can be free-standing or incorporated into shelving modules or stores counters. Subdividers are used, which enable particularly good use of drawer space, and there is a range of other fittings suitable for such items as electronic components, machined items and other delicate components

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Mobile shelving, Just as for palletized stock, there are small item mobile storage systems with shelves mounted on moving platforms, which run along floor-mounted rails. Unlike palletized systems, however, these are not usually powered, but are manually moved by turning a large wheel at the end of each section of shelving

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Flow racks, Small items and cartons can also be held in live storage systems, sometimes referred to as flow racking, with the goods located on inclined roller conveyors

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Miniload, nother mechanized small item storage system is the miniload crane operates in a central aisle to bring goods out of, or put goods into, the storage medium, shelving or tote containers set out on either side of a central crane aisle

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Carousels, Carousels hold material on shelves, or in tote containers on shelves, supported and moved by chains, which are electric-motor-driven to bring specific product lines, as required, to an operator. The objective is to minimize operator movement when accessing inventory, so carousels find application in small items order picking. Carousel units can give fast rates of accession to stock, and are inherently secure

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TRUCK ATTACHMENTS

These attachments may be used for block-stacking the goods or they may be used in conjunction with accessories fitted to adjustable pallet racking. For example, channel supports are available for storing post pallets on APR. Similarly, drum and reel supports are also available. It should be noted that all attachments have weight, and this must be taken into account when calculating the payload capacity of a truck where attachments are used.

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SOME COMMON TRUCK ATTACHMENTS ARE AS FOLLOWS

•      Clamps, Clamp attachments consist of shaped or flat side arms, sometimes also fitted with non-slip surfaces, used for handling loads such as washing machines, bales, drums, kegs and paper reels

•      Rotating head, This device changes the orientation of a load. For example, reels of newsprint are usually stored with their axes vertical, but they are required to be presented to printing machines horizontally

•      Load push-pull, This  device  handles pallet-sized loads assembled  on card  or plastic skid sheets (sometimes referred to as “slip-sheets”)

•      Booms, There are various boom attachments available for placing along the centre of items such as carpets and horizontal reels

•      Multi forks, These are frequently  used  where  unit  loads are  made  from  the tems  themselves.  For  example,  bricks  may  be  strapped  together  leaving a number of slots within the lower layers for such attachments to fit into

•      Drum tines, These are horizontal bars that are used for lifting a number of horizontally oriented drums at once.

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LONG LOADS

Items such as carpets, linoleum, wood and engineering material (eg bar, rod and tube) are not suitable for the standard types of storage system discussed so far, and require special storage and handling

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 CRANES

Cranes are used particularly for moving very heavy loads (such as metal bars) within a predetermined area, but may also be used for lighter loads, for example where items may be just too heavy in relation to manual handling guidelines, Equipment types include

1. Jib cranes
2. Overhead travelling cranes
3. Gantry cranes

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CONVEYORS

Conveyor systems are used for moving material between fixed points, for holding material as short-term buffer (ie accumulation) and for sortation. Both gravity and powered conveyors may be used for the movement of goods. Types of gravity conveyors include chutes, skate-wheel conveyors and roller conveyors. These types of gravity conveyors are normally used for moving goods short distances, for example chutes may be used for transferring goods down from a mezzanine floor whilst mobile skate-wheel conveyors may be used for vehicle loading and unloading

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Conveyor systems may be suitable where some of the following characteristics apply

•      high throughput

•      fixed routes

•      continuous (or intermittent, but frequent) movements

•      uneven floors or split-level operations

The possible disadvantages of conveyor systems include

•      high capital cost

•      obstruction to pedestrian and truck traffic

•      inflexibility for future change

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AUTOMATED GUIDED VEHICLES

•      As well as being used for the movement of pallets (as described in Chapter 15), AGVs may be used for transporting large loads such as car bodies and paper reels. In the latter case, instead of being fitted with roller conveyors to move the load, they may have 'cradled' belt conveyors to hold the reels and to move the reels on to and off the AGV.

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HANGING GARMENT SYSTEMS

These are specialist systems for storing and handling garments on hangers. It is possible for garments to be transported in a hanging condition all the way from garment manufacturers in source countries such as in the Far East through to shops in, for example, the United States or Europe. Road vehicles and ISO shipping containers can be fitted with hanging rails, and warehouses can employ hanging garment systems for storage and for sortation to the individual shops. These systems may be manual in nature or may be highly automated, with garments being put away to reserve storage rails and then order-picked to customer orders automatically under computer control. These activities are based on overhead conveyor systems, as described above, controlling the hanging garments either singly or in batches. The individual garments may be identified by, for example, bar codes, vision systems or radio frequency identification (RFID) tags and, based on this information, the garments may be sorted at the rate of several thousand per hour

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SUMMARY

These have included small parts systems, the use of fork-lift truck attachments, systems for long loads, and the use of conveyors, cranes and AGVs, as well as hanging garment systems the same objectives of achieving the required service and throughput requirements at the least overall cost apply as with palletized systems. The same trade-offs therefore need to be made between such factors as space, accessibility, speed, productivity, safety, accuracy and the minimization of damage

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