Shock 7: Cushion Design

Box Dimensions with Cushion Formula

(Length + 2 × thickness) × (Width + 2 × thickness) × (Height + 2 × thickness)

Foam Weight Calculation

Foam Volume (cu. ft.) × Foam Density (lbs/cu. ft.) [where Foam Volume = Box Volume - Product Volume]

Why are stresses higher on package corners?

Because stress is inversely proportional to area (σ = F/A), and corners have a much smaller contact area than faces.

VanMoof Case Study Finding

Printing an image of a flat-screen TV on bicycle shipping cartons reduced shipping damage by 70%–80% because handlers treated fragile cargo with more care.

Criterion #4: Prevent Movement

If you shake the package and can hear or feel the product shifting, add support to prevent internal movement.

Creep (Cushion Design)

Long-term deformation due to sustained time under load (e.g., warehousing for months can cause as much as 10% deformation).

Cushion Shrinkage

Reduction in cushion size over time that loosens the fit between the product, cushion, and box, allowing product movement.

Domestic Dimensional Weight Formula

(L × W × H) / 166

Export / International Dimensional Weight Formula

(L × W × H) / 139

How are shipping charges determined?

Based on whichever is greater: the actual weight of the package or its dimensional weight.

Static Stress Formula

Static Stress = Product Weight / Bearing Area (σ = F/A)

Criterion #5: Load Distribution

Avoid concentrated loads on large unsupported areas; involve a larger area of contact to lower stress.

Common Standard Organizations for Testing

ASTM, ISTA, ISO, EUMOS, etc.

Fatigue in Cushioning

Evaluated using "2-5 impact" cushion curves to account for multiple impacts during transit, plus corrugated board's cushioning ability.

Packaging Optimization Benefits

Transportation cost savings, material use reductions, improved pallet/cube utilization, and sustainability (reduced waste and CO₂).

Corner Blocks vs. End Caps

Two common protective cushion configurations used to protect product corners and edges without fully enveloping the product in foam.