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Secrets of International Trade

The Pallet
 

Part 1

Part 2

Part 3

  

 
 

The pallet is the cornerstone of the entire materials handling industry and the least understood.

Where cargo handling is concerned, we have come a long way from the days of pulley hoist and rope.
 

The Science of materials Handling, the last frontier against industrial cost -- it embraces a wide diversity of elements, one of which is the most commonplace but yet least understood -- the wooden pallet.
 


The Webster's Dictionary defines the term pallet:
 "A transportable platform used for storage of goods".

Pallets comprise the most versatile unit load system. It consist of a wooden, metal or plastic framework designed to be picked up by mechanical devices--usually, forklift, forklift trucks, pallet trucks, order pickers and stackers, etc.
 

 

 
 

The performance
requirements of a pallet

Since pallets was first introduced, they were made of wood and much effort were expended into the search for an alternative to wood as the basic material.


The Forces
acting on a Pallet

 The stress that occur within a loaded pallet when it is resting on a flat surface is relatively small because the weight is supported by the blocks and only the deck is subjected to a bending force.
 

When the pallet is lifted (by a forklift), the amount of stress present depends on how closely the forks are spaced.
 

The forks of a pallet truck are normally spaced about 686mm apart and in some cases, allowance for narrower fork spacing of 533 mm, and assuming that the racking beams have a 75mm over-hang on each side.


The closer the forks are together, the greater the amount of stress and vice versa. Therefore, when pallets are stacked in blocks and the top surface of the underlying (bottom) load is uneven, the bottom deck boards will be subjected to a certain amount of stress.


A loaded pallet is subjected to higher static stresses when it is supported in ordinary pallet racking or drive-in stacking than when it is lifted by forked machines.


The relative magnitude of the bending moment (ceteri paribus) and the stated conditions. The relative severity of the loading conditions resulting from the different types of support and that the bending moment, increases disproportionately with the size of the pallet.
 

 

 
  The deck of the pallet must have the ability to withstand these bending moments without breaking or deflecting to an extend which puts the load in a precarious position.
 

 
Where a pallet has two decks, the load will be shared so that both decks contribute to the support and the blocks or feet of the pallet will have to bear compression loads, especially for block stacking.

 

 
  In any particular situation, the actual stress that occurs in a pallet will depend very much on the nature of the load -- for example, a load consisting of bags of free flowing material such as rice will result in more stress than an equivalent load made up of large carton boxes.

 

Performance
Criteria of pallets

The adoption of standard pallets is the pivotal point for the standardization of the logistic chain in materials handling. Pallet should be able to resist prolonged exposure to moisture and be fire resistant.

 
 
  • it must be of adequate strength and carry the load it has been designed for in normal handling and storage processes.
     
  • It must have adequate stiffness so that it can carry its load without deflecting to an unacceptable extent.
     
  • It must be resilient enough to resist repeated abuse and accidental damage.
     
  • The coefficient of friction of the deck must be high enough to prevent slippage of loaded goods. The coefficient of friction in the throat, when acting with the fork should also be high enough to prevent the forks from slipping.
     
  • It should be sufficiently light to allow manual handling and its weight / strength ratio should be such that the pallet is not easily damaged when dropped.
     
  • If it is durable, as opposed to expendable, the pallet should be designed for economic repair to an extent depending on the likelihood of its sustaining damage.
     
  • Certain industries call for hygienically clean pallets. For this purpose, the pallet in question should be easily cleaned for the particular purpose.
     
  • Pallets are often required to be stored in the open or carried in open transport. In such instances, they should be able to resist the prolonged exposure to moisture and if used close to high temperature areas, like boilers, they have to be fire resistant.

 
 
Part 1/3 < This Page
Pallets comprise the most versatile unit load system
 

 
 
Part 2/3
Pallets of different materials: metals, plastics, wood and composite compounds
 

 
 
Part 3/3
ISO approved pallets, with four way access for forklifts
 
 
 

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