Category: Material Handling Equipment
Dictionary Definition
There are a great many standard storage arrangements for pallet racking. The
Stores planner can decide on the configuration suitable for a specific need
simply by contemplating a standard layout, the type of material to be stored and
the picking/putting away rates to be achieved. Seven standard arrangements are
given below, with very brief comments on each. Their pro's and con's are
summarised below.
(i) Block Stacking
Unit loads are stacked on top of each other, and stored on the floor in storage
lanes ("blocks"), two to ten deep. Block stacking is suitable only for a very
limited number of different items, where product quantities are large and/or
where products themselves are bulky and turnover is high. Very high storage
density is achieved though ease of access is not good. Also note that block
stacking is strictly LIFO (see below), so that if FIFO is necessary, block
stacking is not a feasible option.
(ii) Single and Double Deep Pallet Racking
Single deep racking is a simple system that is associated with pallet racking
for picking faces (see Two-Step Picking later). It allows immediate access to
every load stored. A major disadvantage, however, is the loss of some 60% of
floor space to aisles. Double deep pallet racking is merely an extension of
single with less loss of space to aisles (but with more honeycombing).
(iii) Drive In and Drive Thru Racking
The racking consists of upright columns with horizontal rails to support
pallets. Storage lanes of the chosen depth reduce space lost to aisles even
more. High density, but suitable only for low/ medium thruput items. LIFO only.
Drive thru merely means access from two sides.
(iv) Pallet Flow Racking
This superior though expensive system is similar to Drive In Racking, except
that loads are moved on skate wheel conveyors. As a load is removed from the
front of the storage lane, the next lane advances to the picking face. Pallet
flow racking gives high throughput and good space utilisation, and permits FIFO.
It is used for high density, high thruput storage, but costs some £200 per
storage position.
(v) Push-Back Racks
As a load is placed in storage, its weight and the force of the FLT (fork lift
truck) pushes back the other loads in the lane. As a load is removed, the rear
loads push forward. Expensive and LIFO.
(vi) Mobile Pallet Racks
Whole rows of rack are moved forward together, eliminating aisles.
Safety is a most important concern with all racking. Training must be given
by the equipment manufacturer and the greatest care exercised to ensure loads
are evenly distributed and that they never exceed the manufacturer's limits.
Operating conditions must also be satisfactory, such as lighting and working
space, and the racking installation must be rigorously inspected on a regular
basis, not simply when someone 'notices something is wrong'... For Racking
Safety Trainining, visit the Storage Equipment Safety Service site.
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