Types of Pallets
Stringer Pallet
A stringer pallet is called that because it uses “stringers,” which support the unit load. The stringers are the boards, typically 2 x 4’s or 3 x 4’s, sandwiched between the top and bottom deck boards.
When specifying a stringer pallet, the length (i.e. the length of the stringer) is noted first, and the width, or length of the deckboards is noted second. Frequently, stringers may be notched to allow for partial four-way fork entry, thus creating a “4-way” stringer pallet. If the stringers are not notched, it is called a “2-way” pallet, with fork entry only from either end. Bottom deckboards can be chamfered to allow entry for the wheels of a pallet jack.
A stringer pallet with no bottom deck boards is called a skid.
Block Pallet
Block pallets are true 4-way entry pallets. They use blocks of solid wood, plywood, or plastic to support the unit load. Typically, block pallets use 4 to 12 blocks to support the top deckboards. Curiously enough, between the blocks and the deckboards are thin stringers, which form a mat with the deckboard. Like in a stringer pallet, the length of a block pallet, is specified by the length of the stringer board and the width by the length of the deckboards. Block pallets can be designed with or without bottom deckboards, or a full-perimeter base.
Both stringer and block pallets can have a variety of deckboard configurations, number, width, and spacing. In addition, plywood or oriented strand board (OSB) can be used as deck material, otherwise known as a “panel deck” pallet.
Terminology
Annularly threaded nail – pallet nail with annular (ring) threads rolled onto shank; ring nail; ring shank nail; ring-threaded nail
Base – structured assembly designed to support unit load
Bearing surface – interface between pallet elements and components
Bin – multi-sided superstructure to be mounted on a pallet base, with or without a cover; also known as a pallet box
Block – rectangular, square, multi-sided, or cylindrical deck spacer
Block pallet – a type of pallet with blocks between the pallet decks or beneath the top deck
Chamfer – machined or molded inclined surface along part or full length of edges of deckboards between stringers or blocks to facilitate passage of fork-arm wheels of pallet trucks and to guide tines of fork lift truck during entry into pallet; bevel
Collar – fixed, hinged, removable, or collapsible horizontal framing members to tie together vertical elements of pallet superstructure
Combo pallet – remanufactured pallet which contains a mixture of recycled and new components
Deckboard – element or component of a pallet deck, perpendicular to the stringers or stringerboards
Deflection – the amount of flexural deformation of a pallet or pallet component due to the weight of an imposed load; sag
Fastener – a device for connecting pallet components to form integral structures, such as nails, staples, screws, bolts, lag bolts, adhesives and welds
Fastener shear index (FSI)– measure of the estimated shear performance a given fastener relative to that of a high-quality “base” nail
Free span – the distance between spacers within the pallet; distance between external pallet supports, as in a warehouse rack
Handling – a single pick-up; movement as a result of picking up, transporting and setting down of an empty or loaded pallet
Hardwood – a wood from broad-leaved tree species (not necessarily hard in texture or dense) like Birch, Maple, Oak and Tamarack
Helically-threaded nail – nail with screw-like threads; drive screw nail
ISPM 15 – International Standards of Phytosanitary Measures Publication No. 15 – Guidelines for regulating wood packaging material in international trade
Lateral collapse – failure of pallet connections caused by excessive lateral force in direction perpendicular to stringer axis or parallel or perpendicular to stringerboard axis
Limited-use pallet – a pallet designed for an average of up to nine trips, assuming an average of five handlings per trip and an average handling environment, before first repair; shipping pallet
MIBANT angle – fastener bend angle providing indication of (fastener) toughness and bending resistance
MIBANT device (Morgan Impact Bend Angle Nail Tester)– a standard impact nail and staple tester used to determine impact-bending resistance and toughness of nails and staples
Multiple-use pallet – a pallet designed for repeated uses for more than one unit load with an average minimum life-to-first repair of 10 trips or more, with an average of five handlings per trip in an average handling environment; multiple-trip pallet; returnable pallet; reusable pallet; warehouse pallet; permanent pallet; general-purpose pallet; special-service pallet; through-transit pallet
Nail – straight, slender, wire fastener made from endless wire by cutting the point and forming the head at the shank end opposite the point, designed to be drive, to hold two or more pieces of wood packaging together
Notch – filleted cutout in lower portion of the stringer to allow entry for the fork tine, usually 9” in length and 1-1/4” to 1-1/2” in height
Pallet – a portable, horizontal, rigid, composite platform used as a base for assembling, storing, stacking, handling and transporting goods as a unit load, often equipped with a superstructure
Pallet size – overall dimension of a pallet typically stated in terms of length followed by width and height; for example, a 48”x40” pallet is 48” long and 40” wide; has 48” stringers or stringerboards and 40” deckboards
Racked across deckboards (RAD) – output of the PDS evaluation software describing the maximum load-carrying capacity and deflection of a wood pallet and its decks, where the warehouse racking frame supports the pallet only at the deckboard ends
Racked across stringers (RAS) – output of the PDS software evaluation describing the maximum load-carrying capacity and deflection of a wood pallet and its decks, where the warehouse racking frame supports the pallet only at the stringer or stringerboard ends
Repaired pallet – pallet with damaged components replaced with new or recycled components, in order to reuse it
Recycled pallet – a pallet that has been used, discarded, salvaged, repaired or rebuilt in order to pass through another cycle or cycles of use
Remanufactured pallet – a pallet newly assembled from recycled components
Skid – a pallet without bottom deckboards or deck
Slave pallet – rigid pallet or platform; single, thick panel used as a support base for a palletized load in warehouse rack-storage facilities or production systems
Softwood – wood from coniferous or needle-bearing species of trees (not necessarily soft in texture or of low density) like Spruce, Pine or Fir
Staple – wire fastener formed by bending wire to form two legs of equal length and a crown connecting both legs at ends opposite leg points
Stiffness – resistance to external force, load, or generation of internal strain
Strength – resistance to flexural deformation in direction of applied force
Stringer – continuous, longitudinal, solid, or notched beam-component of the pallet used to support and space the deck components, often identified by location as the outside, interior or center stringer; bearer; runner
Stringerboard – in block pallets, the continuous, solid board member extending for the full length of the pallet, perpendicular to the deckboard and placed between the deckboards and blocks, to serve as support of deckboards or deck
Stringer pallet – a type of pallet with stringers between the deckboards or beneath the panel deck
Trip – typically a series of four to six handlings of the pallet, required to move a palletized unit load from the shipping point to the receiving point
Uniform standard for wood pallets – a comprehensive standard for the manufacture and repair of wood pallets that’s available through NWPCA; also outlines “best practices”
Unit load – the assembly of goods or a single item on a pallet for handling, moving, storing or stacking as a single entity; it includes the supporting pallet