How to Choose Prepainted Steel Coils

The core principle for choosing prepainted steel coils is “scenario matching, parameter alignment, and cost-effectiveness priority”. You need to lock in key parameters based on usage needs and avoid blind selection. The specific steps are as follows:
I. First, Define the Scenario: Clarify Core Requirements
1. Choose corrosion resistance grade by environment: For general outdoor use (e.g., suburban workshops), select C3-grade corrosion resistance; for coastal high-salt-fog areas or chemical industrial zones (e.g., ports, chemical plants), choose C4-C5 grades; for indoor scenarios (e.g., home appliance casings), C1-C2 grades are sufficient.
2. Choose coating grade by service life: For short-term use (5-8 years, e.g., temporary buildings), acrylic coatings are optional; for medium-term use (10-15 years, e.g., ordinary workshops), polyester (PE) coatings are recommended; for long-term use (over 15 years, e.g., landmark buildings), fluorocarbon (PVDF) coatings are preferred.
II. Second, Align Parameters: Focus on 3 Key Items
1. Base material: Hot-dip galvanized base material offers high cost-effectiveness (suitable for C3-grade environments); hot-dip aluminum-zinc base material has 2-5 times better corrosion resistance than the former (must be selected for C4-C5-grade environments); cold-rolled base material is only used for indoor non-corrosive scenarios (e.g., internal parts of home appliances).
2. Thickness: For building roofs/exterior walls, choose 0.4-0.8mm (select thicker options like 1.0mm for large spans); for home appliance casings, choose 0.35-0.5mm. The thickness must match the bending and cutting capabilities of processing equipment.
3. Coating thickness: The front coating should be ≥20μm for general scenarios and ≥30μm for high-corrosion environments (e.g., fluorocarbon coatings need to reach over 40μm). This can be verified through quality inspection reports to prevent premature peeling due to overly thin coatings.
III. Finally, Compare Prices: Balance Quality and Cost
Prioritize products with ISO9001/14001 certifications and avoid low-cost options (prone to color difference and coating peeling). Meanwhile, calculate the “long-term cost”: for example, in coastal areas, choosing hot-dip aluminum-zinc + fluorocarbon coatings may cost 20%-30% more initially, but it reduces replacement costs for 5-8 years, resulting in higher overall cost-effectiveness.