How to Design Packaging Suitable for Shipping? A Guide to Avoiding Product Damage

Transport Damage Is Not Caused by a Single Factor

When an e-commerce package arrives with an intact outer carton but the product inside is found damaged upon opening, this is an issue that must be addressed during the transport packaging design stage. There are four main causes of transport damage: drop impact, stacking pressure, vibration fatigue, and humidity intrusion. The packaging design stage must focus on targeted design around these four variables, rather than attempting remediation after the product is already damaged.

Once these four variables are understood, packaging design shifts from appearing sturdy to being able to withstand testing.

Variable 1: Drop Impact

Express parcels experience multiple drops on sorting lines, typically from a height of 0.5-1.5 meters. Drop impact is mainly absorbed by cushioning materials. Common cushioning materials include: corrugated board (E-flute, B-flute, C-flute), honeycomb board, pearl cotton (EPE), bubble film, foam plastic, and molded pulp.

For electronic products, glassware, and ceramic items dropped from a height of 1 meter, the cushioning material thickness is recommended at 20-50 mm; liquid or semi-solid products (such as bottled beverages) require snap-fit or fixation structures to prevent internal movement. Drop testing is recommended with reference to ISTA 1A or ISTA 3A standards.

Variable Two: Stacking Pressure

During transportation and warehousing, packaging boxes are stacked in multiple layers. The bottom box bears the pressure equal to the sum of the weights of the boxes above it. The compressive strength of a corrugated carton is determined by the flute type, board grammage, and moisture content. B-flute offers high compressive strength and is suitable for medium to heavy products; E-flute offers lower compressive strength and is suitable for lightweight products.

When the stacking layers exceed 5, it is recommended to use B-flute or double-wall corrugated material for the outer carton; for fewer than 3 layers, E-flute can be used. Pay attention to moisture protection to prevent an increase in the carton moisture content from causing a reduction in compressive strength.

Variable Three: Vibration Fatigue

During long-distance transportation, the continuous vibration from trucks and aircraft causes packaging units to repeatedly withstand micro-impacts. Vibration fatigue can loosen product connections, cause screws to fall off, and produce cracks in glass products. The density and thickness of cushioning materials determine the cushioning effect; if the density is too low (e.g., below 10 kg/m³), cushioning is insufficient, and if it is too high (e.g., above 30 kg/m³), it loses cushioning effectiveness.

Recommended cushioning material densities: EPE pearl cotton 20-28 kg/m³, pulp molding 30-50 kg/m³, and bubble film selected according to bubble diameter. Packaging units typically endure 1-4 hours of continuous vibration during vibration testing.

Variable Four: Humidity Intrusion

During ocean shipping and transportation in the southern rainy season, packaging may be exposed to high-humidity environments for extended periods. When humidity exceeds 80%, the compressive strength of corrugated cartons drops by 30%-50%. Waterproof treatment options include: laminating the carton surface (PP or PE film), lining the carton with PE bags, placing desiccants, and using waterproof corrugated board.

Food contact applications must comply with GB 4806.8-2022, and waterproof materials must be food-grade or isolated from food.

Box Type Selection: Mailer Boxes and Corrugated Cartons

The mailer box (Mailer Box) is folded into shape as a single piece, requiring no gluing or only a small amount of adhesive, and features a sturdy structure, making it suitable for e-commerce small-parcel shipping. Corrugated cartons are the mainstream choice for traditional transport packaging, available in ply counts ranging from single-wall to seven-ply. Lightweight products (within 1 kg) can use single-wall E-flute corrugated; medium-weight products (1–10 kg) use double-wall B-flute or E+B flute; heavy-duty products (10–50 kg) use three-ply or five-ply corrugated.

Sealing Methods and Waterproof Treatment

Standard carton sealing tape is suitable for short-distance transport; hot-melt adhesive tape or a tape-plus-staple combination (U-shaped staples) is suitable for long-distance transport. Waterproof treatment is applied to the outer carton, and lamination or the addition of a PE bag to the carton is acceptable. It is worth noting that over-sealing can actually impair cushioning performance during drops; it is recommended to maintain a buffer space of 5-10 mm.

Transportation Packaging Design Process

First, determine the cushioning solution based on the product's weight, volume, and fragility; then determine the outer carton specifications according to the transportation distance, stacking layers, and humidity conditions; finally, verify the design through drop testing, vibration testing, and stacking testing. Once the tests are passed, proceed with mass production to avoid trial and error directly on the product.