1.Why are galvanized coils being considered?
Excellent rust and corrosion resistance: Cold chain logistics environments are humid with large temperature differences between the inside and outside of the vehicle, making condensation very likely. The zinc layer of galvanized coils provides effective sacrificial anode protection, preventing the steel substrate from rusting, and its corrosion resistance is far superior to ordinary cold-rolled sheets.
High cost-effectiveness: Compared to stainless steel and composite materials, galvanized coils are less expensive, helping to control overall vehicle manufacturing costs.
Strength and rigidity: As a type of steel, it possesses excellent structural strength and rigidity, capable of withstanding cargo loads and a certain degree of impact.
Mature processing technology: It is easy to shear, bend, stamp, and weld, and has good compatibility with existing vehicle body manufacturing processes.
2.Why isn't it the best choice?
Weight Issues: The high density of steel results in a heavier truck body, directly impacting cargo capacity and fuel efficiency (or electricity consumption). This is a significant drawback for weight-based logistics.
High Thermal Conductivity (A Fatal Flaw): Steel is an excellent conductor of heat. Using galvanized steel sheets for the truck body creates a thermal bridge, allowing external heat to easily transfer into the interior, greatly increasing the load on the refrigeration unit, leading to higher energy consumption and difficulty maintaining a stable low-temperature environment.
Condensation Risk: Although the galvanized layer is rust-proof, condensation can still form on the cold metal surface when exposed to humid air. If the interior walls are directly metal, water droplets will drip onto the cargo, affecting packaging and product quality.
Corrosion After Surface Damage: The galvanized layer is easily scratched during loading and unloading. Once the zinc layer is damaged, the exposed steel substrate becomes a corrosion initiation point in a humid environment, affecting the vehicle's lifespan.
Interior Issues: The smooth and hard metal surface makes it difficult to secure cargo and easily damages packaging during collisions.
3.How effective is it as a skin for composite panels?
Structure: Two layers of skin, inner and outer, plus an intermediate insulation material (such as polyurethane foam).
Outer Skin: Typically made of galvanized or aluminized zinc coil. Exposed to the elements, it withstands wind, rain, sun, and minor impacts; its corrosion resistance is crucial.
Inner Skin: While galvanized sheet was also used in the past, fiberglass reinforced plastic (FRP) or food-grade stainless steel are now more common. FRP has a smooth, condensation-free inner wall, is easy to clean, insulating, and corrosion-resistant.
Core: High-density polyurethane foam is injected in the middle; its excellent insulation properties effectively block thermal bridges, ensuring the thermal insulation of the carriage.
4.What type of profile should be selected as the frame of the carriage?
The load-bearing frame (square steel, section steel) of the carriage is often made of galvanized material or hot-dip galvanized profiles to prevent slow corrosion from the inside and ensure structural safety.
5.What type of profile should be used for low-end/light-duty car bodies?
For some scenarios with limited budgets and less stringent insulation requirements, or for the cargo boxes of small refrigerated trucks, a simple structure of single-layer galvanized sheet or "sheet metal insulation" may still be used. However, this is gradually being phased out by the market.