1.Why is it that the thicker the zinc layer, the more difficult it is to process?
The zinc layer is relatively soft and easily adheres to molds.
Zinc metal is much softer and more adhesive than the underlying steel substrate. During stamping, shearing, and bending, a thick zinc layer is more likely to peel off and stick to the surface of molds, tools, or rolls, forming zinc dross accumulation. This not only scratches the workpiece surface but also leads to more frequent cleaning and maintenance of molds, affecting production efficiency and product yield.
Zinc layer peeling and micro-crack problems
During bending or deep drawing, the outer zinc layer is stretched while the inner layer is compressed. If the zinc layer is too thick, it cannot stretch as uniformly as the steel base during deformation, making it more prone to peeling off from the substrate or forming micro-cracks. This not only affects aesthetics but also disrupts the continuity of the coating. In corrosive environments, these cracks and peeling areas become the starting points for preferential corrosion.
Impact on dimensional accuracy and surface quality
The zinc layer itself has thickness. During high-precision cold bending, a thick and potentially uneven zinc layer can affect the dimensional tolerances of the final profile. At the same time, the zinc layer surface is more easily scratched during processing, affecting the appearance of the finished product.
2.What are the specific characteristics under different processing methods?
Stamping and shearing: A thicker zinc layer leads to faster tool wear, potentially resulting in larger burrs and increased sticking to the tool.
Bending: A thicker zinc layer necessitates a larger minimum bending radius; otherwise, the outer zinc coating is prone to cracking or peeling.
Deep drawing: A thicker zinc layer makes the surface more susceptible to orange peeling and flaking.
3.How should zinc coatings be selected for highly corrosive environments?
For applications such as outdoor construction, coastal areas, and industrial zones, materials with thicker zinc coatings (e.g., Z120, Z150, or even higher) must be selected. In such cases, it is necessary to accept the fact that the processing is more difficult and the requirements for molds and equipment are higher, and this can be addressed by optimizing the process (e.g., using specialized molds and adjusting processing parameters).
4.How to choose a zinc coating for ordinary or indoor environments?
For dry indoor door frames and furniture, materials with a thinner zinc coating (such as Z60 or Z80) can be chosen. This makes processing easier and may also reduce costs.
5.How should we weigh the pros and cons when choosing materials?
For optimal corrosion resistance, choose a thick zinc coating, accepting higher processing difficulty and costs.
For optimal processability and economy, choose a thin zinc coating, ensuring it meets the corrosion resistance requirements of the operating environment.