Humans absorb variation; machines do not
A forklift operator encountering a slightly warped pallet adjusts. They tilt the mast, approach differently, or simply pick it up more carefully. An automated shuttle does none of those things. It executes the same motion and either succeeds or jams.
This is the single most important thing to understand about automating a warehouse: your pallet specification stops being a guideline and becomes a mechanical requirement.
The five tolerances that matter
Overall dimensions, usually specified to ±1/4 inch or tighter. Squareness, measured on the diagonal. Bottom-surface flatness, because conveyor rollers and shuttle forks need a consistent plane. Absence of protruding fasteners, which jam and scratch. And absence of loose or missing bottom boards, which is the most common automated-system jam we hear about.
Note that none of these are strength requirements. Automation failures are almost always geometric, not structural.
Why block pallets win here
Block construction gives a continuous perimeter base, which presents a far more predictable surface to a conveyor than three stringers with gaps between them. They also hold squareness better over repeated cycles.
Our standing recommendation for any customer commissioning automation: block pallets, written tolerance, and a pre-screening pass on every unit. We do that screening as a service because a jammed line costs more per hour than a year of extra sorting.
Can recycled pallets run in automation?
Yes, with a caveat. Recycled block pallets screened against a written tolerance run perfectly well in most automated systems. We have customers doing exactly this at volume.
The caveat is that the screening is real work and the yield is lower. Expect to pay for a graded, screened pool rather than general A-grade stock. It will still cost substantially less than new.
The commissioning-week conversation
If you are commissioning a system, bring your pallet supplier into the conversation before go-live, not after the first jam. We have been called in during week three more than once, and the fix was always something that would have taken ten minutes to specify in advance.
Bring us the integrator's tolerance document. If the integrator has not provided one, that is the first thing to chase.