martes, 17 de abril de 2012

Pallet & Lumber Terminology


Pallet & Lumber Terminology

Pallet Components
• There are two basic styles of pallets: Stringer Pallets and Block Pallets.
• Stringer Pallets are constructed with two basic components: Deck Boards and Stringers.
• Deck boards are the top and bottom boards (or “slats”) and are typically made of 1" or ½" material. There are
usually more top boards than bottom boards. Deck boards are fastened to the Stringers.
• Stringers (or “runners”) provide support for the deck boards. Most pallets have 3 stringers. Stringers are typically
made from 2x4" or 1½x4" material.
• Block Pallets are made up of Deck Boards, Stringers Boards and Blocks. The stringer boards are typically
attached to the blocks to form runners. The deck boards are then attached to these runner assemblies.
• When a pallet has the exact configuration on the top as it does on the bottom deck, it is referred to as “reversible
pallet”.
• Pallets with a different configuration top and bottom are referred to as “non-reversible”.


Pallet Description
• Usually consists of two dimensions: Length x Width. In North America, the dimensions are typically quoted in
inches (eg. 48 x 40"). Industry norm is to describe a pallet using its Length first, followed by its Width.
• Length is defined as the stringer length while Width is the length of the deck boards. On a stringer pallet, the Width
is also the main forklift entry point.
• Some refer to the dimensions in the reverse order (eg. 40 x 48"), but may still be referring to a pallet that is 48" long
by 40" wide.
• Some refer to pallets with 3 dimensions: Length, Width and Height.


Dimensions – Nominal vs Actual
• The height and thickness of boards and stringers is typically described in nominal terms, rather than actual.
• Stringers are typically described as being “2x4", but their actual dimensions are smaller, typically 1½” x 3½”.
• Lumber is usually purchased in Board Footage, which is calculated using nominal dimensions.


Lumber Species
• Wooden pallets are constructed of two main types of lumber: Softwood and Hardwood.
• The term “softwood” actually describes many species. In Canada the three main species used in pallet-grade
softwood are Spruce, Pine and Fir, also known as SPF.
• The term “hardwood” describes several species as well, such as Maple, Oak and Cherry.
• Softwoods are less dense and, thus, weaker than Hardwoods.
• Pallets can also be made of a combination of the two materials (eg. S/W boards and H/W stringers).
• Pallets can also be made from Aspen (or Poplar), which is actually a low-density hardwood, but looks and
performs more like a softwood.


Heat Treating
• Heat treating is the process of putting lumber in a kiln for a certain length of time until a desired core temperature
is achieved or until a desired moisture level is reached.
• Heat treating to a core temperature is a fairly new phenomenon, brought on by recent concerns over the unwanted
global movement of timber destroying pests in wood packaging exports. Most industrialized nations adhere to a
standard international regulation (ISPM-15), which requires that wood packaging intended for export must be
heated in a kiln until its core temperature reaches 56 degrees celsius for a minimum period of 30 minutes. Once
this is achieved, it is generally accepted that most pests are permanently destroyed and no new pests will enter
the wood.
• Manufacturers of HT packaging in Canada must be certified by the Forestry branch of the Canadian Food
Inspection Agency (CFIA). Each certified manufacturer is given a unique identifying number, which must be
stamped on all HT products sold. This stamp lets all importing bodies know that the wood packaging is certified to
be heat-treated and pest-free.
• Some countries may also require a HT certificate in addition to the above stamp.
• Heat treating to achieve a certain moisture level is commonly referred to as “kiln-drying”. This process is done to
lower wood’s natural moisture level so as to prevent warping in high-value or performance-critical applications
(eg. home building).
• Softwood is the most economical choice for heat treated packaging, because of the abundance of kiln-dried
softwood in the marketplace.
• Pallet-grade hardwood lumber is typically not heat treated, due to the cost of longer drying/heating times.• A professionally-designed softwood pallet can typically perform comparably to a hardwood pallet in most
applications.


Rough vs Dressed lumber
• Regardless of species, lumber is typically described as being rough or dressed, which refers to how the material
has been sawn and/or planed.
• “Rough” lumber has not been planed and is, therefore, thicker and has a rougher texture than “dressed” lumber.
• Rough is also typically “green” (ie. not kiln-dried) because it is culled from the lumber manufacturing process before dressing and kiln drying.
• Dressed lumber has been planed and is typically kiln-dried. It is thinner and narrower than Rough lumber of the
same nominal dimension. Eg. A dressed 2x4” has actual dimensions that are smaller than a rough 2x4”.
• Dressed lumber is not necessarily “weaker” than Rough lumber. The kiln drying process actually allows dressed
lumber to perform as well as green rough lumber in certain environments.

Pallet Design
• A very important part of pallet use.
• A pallet’s design must take into account the following things:
- Maximum load going on the pallet
- If the loaded pallets are stacked and how high (at any stage in distribution)
- If the loaded pallets are to be stored in racking (at any stage in distribution)
- If the pallets are primarily for shipping or for in-house use
- Type of material handling equipment used throughout the distribution process
- Details of the product that is going on the pallet (shape, number and location of the packages).
2-way vs 4-way entry
• Pallets that can be lifted only from the two main openings at the front and back are referred to as 2-way entry.
• Pallets that can also be lifted through their sides are referred to as 4-way entry.
• Pallets that are 4-way are often referred to as “notched”, as the stringers must have two notches cut out of them
to permit forklift entry. This type of pallet is technically known as a “partial 4way entry”, because only forklifts can
access the side notches.
• The notches are typically centred along the side of the pallet and their location is set so that they line up with the
forks of most lift trucks. The distance from the end of the stringer to the start of the notch is referred to as the heel,
block or leg.
• “Full 4way access” means that all types of handling equipment can enter from all 4 sides. The most common form
of this type of pallet is a block pallet.
Chamfering
• Chamfering involves putting a beveled or rounded edge on the top surface edges of some or all of the Bottom
boards. This is done using special lumber processing equipment.
• The chamfer creates a “ramp” effect, allowing the wheels of certain material handling equipment to roll over the
bottom boards easily.




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