Creep
Creep is the gradual increase in deflection of a pallet that carries a load over time, even though the load does not change. Wood and especially plastic pallets creep, which is why PDS reports deflection after 30 days and why test standards include hold periods.
Also called long-term deflection, creep deflection
Reviewed
How creep is handled in ratings
| Method | Creep treatment |
|---|---|
| PDS analysis | reports estimated deflection after 30 days under load |
| ASTM D1185 | stiffness test includes a 2 hour creep period |
| ISO 8611 (plastic pallets) | creep periods of 24 to 48 hours |
Forklift handling is treated as short-term loading, so creep matters mainly for rack storage and floor stacking.
What makes creep worse
- Long storage: pallets that sit in racks for weeks sag more than on day one
- Moisture: wet wood creeps more than dry wood
- Material: plastic pallet ratings are usually governed by stiffness and creep rather than strength, and depend strongly on temperature and load duration
- Heavy loads close to the rating
Why it matters
A pallet that passes a short test can still sag off rack beams after a month. When pallets will be racked or stacked for long periods, specify a deflection limit and ask whether the rating accounts for long-term load. See pallet deflection.
Questions
- Do plastic pallets creep more than wood?
- Plastic pallet ratings are typically governed by creep and stiffness, and depend heavily on temperature and load duration, so creep is a bigger design factor for plastic.
Related
- DeflectionDeflection is how far a pallet sags under load. Typical limits are about 2% of span in racking (about 0.75 in on a 44 in span) and 0.5 in for automated systems.
- Rack storageRack storage means a pallet spans between two rack beams with nothing underneath. It gives the lowest rating, e.g. 1,558 lb racked vs 5,223 lb on the floor.
- Pallet deflection: limits, creep and how to reduce sagPallet deflection is how far a loaded pallet sags. Typical limits: about 2% of span in racks, 0.5 in or less for automated systems. How creep affects it.
- Plastic pallet: types, load ratings and how to specify onePlastic pallets are HDPE or PP catalog products rated three ways: static, dynamic and rack. Nestable, stackable and rackable types, costs and how to specify.
- Cruciform baseA cruciform base is a block-pallet bottom with a perimeter frame plus center boards forming a cross. It adds support under the center block in both directions.
- Cut listA pallet cut list gives the pieces of each size needed for an order: parts per pallet x pallets. 1,000 GMA pallets need 8,000 boards at 5/8 x 3-1/2 x 40 in.