Pallet Load Stability

The critical tilt angle is the angle at which the palletized unit's center of gravity (CG) passes over the pallet edge, causing it to tip. The calculator analyzes the load and pallet together. The combined CG is measured from the ground (the pallet bottom, where tipping pivots), so it includes the pallet deck height and folds in the pallet tare at the pallet mid-height when a uniform pallet-mass assumption is used, which lowers the CG. The angle is angle = arctan(half-span / combined CG height), where the half-span is half the pallet footprint in the tipping direction, adjusted by CG offset from center: reduced when the CG shifts toward the tipping edge and increased when it shifts away. A higher CG lowers the angle. The length, width, and corner directions are each checked, and the lowest (weakest) governs.

During transport, loads experience horizontal forces from braking, cornering, and road irregularities. Common European road-securing references use 0.8g forward (braking), 0.5g lateral (cornering), and 0.5g rearward. The calculator converts the critical tilt angle to an equivalent acceleration in g-units (a/g = tan(critical angle)) to screen whether the unit can resist these forces without additional securing.

Beyond tipping, the calculator screens whether the bottom boxes can carry the weight stacked on them. Each box can withstand a box compression test (BCT) value, estimated from the McKee formula (BCT = 5.87 x ECT x sqrt(caliper x perimeter)) or entered directly. The effective BCT derates the lab value for humidity, storage time, and the stacking pattern, since interlocked or misaligned layers can significantly reduce effective compression capacity by shifting load away from ideal column paths. The load on each box is the static weight of the boxes above it, distributed by footprint overlap for interlocked patterns. A static safety factor (2.0 to 4.0x by storage duration) sets the safe working load. For planning, the calculator also applies a higher dynamic screening target, roughly 1.5x the static target, to account for vibration and shock in distribution.

Load stability has two failure modes: tipping (the load rotates over the pallet edge) and sliding (the load shifts horizontally on the pallet surface). This calculator focuses on tipping, which is the dominant failure mode for tall or top-heavy loads. Sliding is governed by friction between the bottom case and the pallet deck, and between stacked layers. Anti-slip sheets, stretch wrap containment force, and pallet surface texture all increase sliding resistance. In practice, check both modes: a load may resist tipping but slide if the coefficient of friction is low.

If the calculator shows a marginal or failing tilt angle, consider these corrective actions: lower the center of gravity by placing heavier cases on the bottom layers; widen the support footprint by using a larger pallet or ensuring no overhang; add anti-slip sheets between layers to increase interlayer friction; increase stretch-wrap containment force, verified with a containment-force or wrap-force measurement method; add corner boards or edge protectors to improve unitization and distribute restraint forces, especially for column-stacked loads; reduce stack height if the CG is too high relative to the footprint. The goal is to raise the critical tilt angle above the transport threshold with margin.