Pallet nails are specialized fasteners, usually ring-shank or helical (screw-shank), designed to resist withdrawal as wood dries and the pallet flexes in service. The joints, not the boards, are often the first thing to fail in a pallet, so the nail type, hardness, length and pattern are as important to performance as the lumber.
Why fasteners matter
A pallet is a structure held together by hundreds of small joints. In use, every forklift lift, drop, rack span and stack applies shear and withdrawal forces to the nails. As green or damp wood dries, it shrinks and loosens its grip on a smooth nail. Poorly chosen fasteners cause boards to work loose, nails to protrude and decks to separate, which leads to product damage and operator injuries.
Fastener performance depends on four things: the nail's shank shape, its diameter and length, its steel strength and the wood it is driven into. Dense hardwoods hold nails strongly but split easily, so nail diameter and point shape must be matched to the species; see wood density and strength table.
Main fastener types
| Type | Shank | Holding behavior | Typical use |
|---|---|---|---|
| Smooth (bright) nail | Plain cylinder | Lowest withdrawal resistance, loosens on drying | Light, one-way or short-life pallets |
| Ring-shank (annular) nail | Series of rings along the shank | High withdrawal resistance as wood fibers lock between rings | Pallet decks, general production |
| Helical (screw-shank, spiral) nail | Twisted threads | High withdrawal resistance; turns as driven | Hardwood pallets; durable pallets |
| Staple | Two legs, driven in pairs | Low cost, fast, lighter holding | Light pallets, container-grade items |
| Screw | Threaded with head | Very high holding; easy to disassemble | Special pallets, boxes and crates |
Smooth nails are the cheapest but can pull out under load when wood dries. Ring-shank nails are the most common in many markets because they hold well while remaining inexpensive. Helical nails twist into the wood and typically offer strong resistance in hardwood, though they can be harder to drive and to remove during repair.
Nail features that affect performance
- Diameter: thicker nails resist bending and shear, but increase splitting in dry boards and end grain.
- Length: the nail needs enough penetration into the support (block or stringer) to develop holding strength, and often long enough to clinch (bend) through the other side, though length depends on board thickness.
- Head: a large head resists pull-through of the deck board. Flat or countersunk heads reduce snagging.
- Point: diamond, chisel or blunt points influence splitting and driving speed.
- Hardness and heat treatment: hardened nails resist bending when driven into dense wood, but too hard a nail can be brittle.
- Coating: bright, galvanized or resin-coated nails vary in withdrawal and corrosion resistance; resin or cement coatings can raise driving friction.
- Corrosion: galvanized nails reduce staining and rust in damp or outdoor service.
Testing fasteners
Pallet fasteners are assessed in laboratories, and the same ideas apply in plant quality checks.
Nail bending. The MIBANT test, the Morgan Impact Bend Angle Nail Test, evaluates nail quality by impact bending to predict how a nail behaves in use. Virginia Tech's pallet testing laboratory uses it alongside other tests.
Withdrawal resistance. A nail is driven into a standard piece of wood and pulled out while the force is recorded. ISO 12777-2 specifies methods for determining the withdrawal and head pull-through resistance of pallet nails and staples. Virginia Tech also reports a fastener withdrawal index and a fastener shear index based on ASTM methods, which allow nails to be ranked.
Head pull-through. Measures the force needed to pull the head through the deck board, which matters under impact or when a pallet is lifted by the deck.
Results in practice: the pallet performance standards, such as ANSI MH1 in the United States, rely on tested fastener behavior within the whole pallet system. See pallet testing standards for the full pallet test set.
Fasteners in the EPAL Euro pallet
The EPAL Euro pallet uses 78 nails arranged in a prescribed, even pattern, which EPAL says gives the pallet its diagonal rigidity. Approved EPAL nails carry a two-letter identification mark on the head so that inspectors can verify that the right fasteners were used during repair and production. The exact nail dimensions and types are set in EPAL's technical regulations, available to licensees, and they should be taken from that source rather than from general guides. For the complete picture, see the EPAL Euro pallet and EPAL licence.
Coil nails versus strip nails
Production machines are fed in one of two ways:
| Feature | Coil nails | Strip (stick) nails |
|---|---|---|
| Collation | Wire-welded or plastic-collated into coils holding many nails | Straight sticks held by paper, plastic or wire |
| Capacity | Few reloads; suits automatic nailing machines | More frequent reloads; used in hand guns |
| Use | Nailing machines and lines | Portable pneumatic nailers |
| Nail types | Ring, helical or smooth available | Ring, helical or smooth available |
Coil nails minimize downtime in automatic equipment; see pallet nailing machines. Manual and repair work uses stick nails and pneumatic guns; see pneumatic nail guns.
Choosing the right fastener
Match the nail to the application:
- Wood species and moisture. Dense hardwood needs strong, sharp, hardened nails of smaller diameter to avoid splits; green wood benefits from ring or helical shanks because it will shrink.
- Pallet life. One-way pallets may use cheaper nails; reusable pallets deserve ring-shank or helical nails and sometimes clinching.
- Load and handling. Racked or heavily stacked pallets need strong joints.
- Machine compatibility. Nail dimensions and collation must match the nailer.
- Standards and customer specification, including EPAL or other pool requirements.
- Repair strategy. Repairable pallets need nails that can be removed without destroying the wood. See pallet repair.
Common problems
- Splitting from nails driven too close to board ends or edges; solved by staggering and using blunt points
- Overdriven or underdriven nails; the head should sit flush with the board
- Protruding points that injure workers and damage goods
- Bent or broken nails from poor quality steel or low air pressure
- Wrong nail pattern, which reduces stiffness
Visual and measured checks form part of pallet quality control.
Frequently asked questions
What is the best nail for wooden pallets?
There is no single best nail. Ring-shank nails are the most common all-round choice, helical nails suit hardwood and reusable pallets, and the specification should follow wood species, load and customer standards.
What is the difference between ring-shank and helical nails?
Ring-shank nails have circular ridges that lock the wood fibers, while helical nails have a spiral thread that twists into the wood as they are driven. Both resist withdrawal far better than smooth nails.
How many nails does a Euro pallet have?
An EPAL Euro pallet is built with 78 nails in a prescribed pattern.
What does the MIBANT test measure?
It measures the bending behavior of a nail under impact, which indicates nail quality and how it will perform in a pallet.
Sources
- Pallet Fastener Testing — Virginia Tech Center for Packaging and Unit Load Design
- ISO 12777-2: Methods of test for pallet joints — Determination of withdrawal and head pull-through resistance of pallet nails and staples — British Standards Institution
- EPAL Euro Pallet Quality Characteristics — European Pallet Association
- Nail Quality Inexpensive But Effective — Pallet Enterprise
- EUR-pallet — Wikipedia