1.Why are cold-rolled coils particularly suitable for making cold-formed shelving?
Cold bending is a process that uses a series of continuous rollers to gradually bend metal strip into a specific cross-sectional shape at room temperature. The characteristics of cold-rolled coils are perfectly suited to this process:
Excellent surface quality: Cold-rolled coils have a smooth, flat surface free of oxide scale, resulting in aesthetically pleasing shelving units that can be painted without additional treatment, with excellent coating adhesion.
Precise dimensional tolerances: The precise control of thickness and width in cold-rolled coils ensures dimensional consistency and stability of the shelving components after forming, which is crucial for shelving systems requiring high-precision assembly.
Good formability: Annealed cold-rolled coils (typically SPCC-SD, i.e., "soft state") possess excellent plasticity and ductility, capable of withstanding complex bending, curling, and ribbing deformations during cold bending without cracking.
High strength and stiffness: Compared to hot-rolled coils, cold-rolled coils achieve higher strength through work hardening, allowing shelving units to maintain sufficient load-bearing capacity even with thinner and lighter materials.
2.What is the standard production line process for cold-formed shelving?
Cold rolled coil uncoiling → Straightening → Roll forming → Fixed-length cutting → Punching/riveting → Welding (for some parts) → Surface treatment (corrosion protection core) → Packaging
3.How to choose materials?
Grade: The most commonly used materials are SPCC (Chinese standard) or DC01 (European standard) soft-state (A or SD) materials to ensure good cold bending performance.
Surface: For ease of subsequent corrosion protection, hot-dip galvanized steel coils (SGCC) or electro-galvanized steel coils (SECC) are preferred as the base material to achieve "substrate corrosion protection".
Thickness: Depending on the rack load-bearing design, cold-rolled coils with a thickness of 1.0mm to 3.0mm are typically used.
4.How to perform anti-corrosion treatment on the surface?
Shelving is typically located in a warehouse environment, which may be susceptible to moisture and condensation, making corrosion prevention crucial.
Preferred Solution: Galvanized Substrate + Powder Coating
Using galvanized steel coils (SGCC/SECC) as raw material provides an initial cathodic protection layer.
After cold bending, phosphating pretreatment is performed, followed by epoxy resin powder coating or polyester coating. This creates a double protection of "galvanized layer + organic coating," resulting in a long lifespan and good appearance. This is the standard process for mid-to-high-end shelving.
Economical Solution: Cold-Rolled Substrate + Overall Post-Processing
Using ordinary cold-rolled coils (SPCC) for forming, followed by overall hot-dip galvanizing. Excellent corrosion resistance, but the surface may not be perfectly smooth and aesthetically pleasing, and high temperatures may cause slight deformation.
Alternatively, a complete coating line of "pickling and phosphating + electrophoretic primer + powder coating" can be used. Excellent performance, but a larger investment.
5.How to determine the materials needed?
For light and medium-duty shelving, galvanized cold-rolled coil (SGCC) is used directly.
For shelving with high load-bearing capacity and appearance requirements, a combination of cold-rolled coil substrate and a complete coating line is used.
While ensuring performance, annealed soft materials are selected to guarantee the quality of cold bending.