1.What impact do packaging quality and structure have?
Packaging Strength: This is the most important factor. The quantity, strength, and distribution of the steel straps/iron bands directly determine the amount of vertical pressure it can withstand.
Corner/Edge Protection Quality: Corner or edge protection effectively prevents direct contact between rolls and distributes pressure.
Rust-Proof Paper/Film: Inner packaging can prevent rust, but its resistance to external pressure is limited.
2.What are the effects of the inherent condition of cold-rolled coils?
Coil weight and size: Heavier and larger diameter coils exert greater pressure on lower coils.
Coil "hardness": Hardness here refers to the hardness grade of the steel coil and the winding tension. Softer steels (such as some deep-drawing steels) are more prone to permanent deformation ("flattening").
Mandrel type: Is it a solid steel core (high strength) or a paper/plastic core (extremely low strength, mostly for small coils or special purposes)?
3.What are the effects of warehousing equipment and conditions?
Ground Load Capacity: The design load capacity of the warehouse floor (usually measured in tons per square meter) is a rigid upper limit. Excessive stacking can lead to floor cracking or even collapse.
Stacking Methods:
Upright Stacking: Good stability, can usually be stacked higher, but requires specialized saddles.
Horizontal Stacking: Directly laid flat on the ground or on dunnage, slightly less stable, limited in the number of layers, and must ensure that each layer is aligned, otherwise it is very easy to roll and slip.
Dunnage/Saddle Condition: Using flat, sturdy dunnage can evenly distribute pressure, which is crucial for safe stacking.
4.What are the industry-standard guidelines?
General Safety Stacking Height: Under conditions of intact packaging, a solid floor, and proper handling, the most common stacking height is 3 layers. This strikes a balance between safety and space utilization.
Conservative Stacking Height: For high-value steel coils with high surface requirements or softer materials (such as automotive outer panels), or coils with general packaging, a stacking height of only 2 layers is recommended.
Maximum Stacking Height: Under conditions of exceptionally robust packaging (such as heavy-duty export packaging), the use of specialized saddles, sufficient floor load capacity, and very strict management, stacking can reach up to 4 layers. Stacking beyond 4 layers is extremely rare and carries a very high risk.
Horizontal Stacking Height: Generally, no more than 2 layers are allowed, and the bottom layer must have anti-rollover measures. Layers must be separated and aligned using flat wooden blocks.
5.What are the key recommendations?
Follow supplier requirements: The most authoritative basis is to check the factory label and accompanying technical documents of the steel coils. Manufacturers usually provide clear recommendations on the "maximum permissible stacking layers," which are calculated based on their packaging design and must be followed.
Assess your own conditions: Clearly understand the floor load of your warehouse and use qualified wooden blocks and saddles.
Store by category: Steel coils of different specifications, packaging, and for different customers should be managed in separate areas, with the stacking height determined by the minimum permissible layer count for each area.
The "safety first" principle: Never blindly increase stacking height to save storage space. The losses from a collapse will far outweigh the saved rental costs. Personnel safety is also a red line that cannot be crossed.