1.What should I pay attention to when cutting?
Shearing: Use a shearing machine for straight-line cutting. Keep the tool sharp to avoid excessive burrs that may damage the zinc layer.
CNC punching: Use a CNC turret punch press for contour punching, trimming, grooving, etc.
Note: The mold gap should be appropriate (usually slightly larger than ordinary cold-rolled plates) to reduce zinc peeling. Choose a sharp mold to reduce burrs. Clean up zinc chips on the mold in a timely manner.
2.How many types of cutting processes are there?
Laser cutting: A very common method with high precision, relatively small heat-affected zone, and smooth kerf. Parameters (power, speed, air pressure) need to be optimized to obtain a good section and reduce slag and zinc layer gasification/oxidation.
Plasma cutting: Suitable for thicker plates, faster speed, but large heat-affected zone, the cut quality (roughness, slope) is usually not as good as laser, and the zinc layer is severely ablated, and the edge needs additional processing.
Water jet cutting: Cold cutting, no heat effect, no damage to the zinc layer, suitable for heat-sensitive or extremely high edge quality occasions, but slower speed and higher cost.
3.What are the key points to pay attention to when processing SECC galvanized sheets?
Protect the zinc layer: The core goal of all processing steps is to minimize physical damage (scratches, indentations, peeling) and chemical damage (corrosion) to the surface zinc layer.
Tools and molds: Use special or compatible tools and molds in good condition (clean, sharp, smooth), and optimize parameters (gap, pressure, speed).
Lubrication: Use correct and sufficient compatible lubricants in forming (especially stamping and stretching) and some cutting processes.
Welding: Pay special attention to the problems caused by zinc evaporation (spatter, pores, smoke, electrode adhesion), and adjust process parameters and equipment.
Pretreatment: Before any subsequent surface treatment (especially spraying), strict and effective cleaning and chemical conversion treatment must be carried out to ensure adhesion.
Environment and safety: Zinc smoke generated during welding and grinding is harmful, and ventilation and personal protection must be done. The handling of chromium-containing passivating agents must comply with environmental regulations.
4.What is the surface treatment process of SECC?
Passivation: SECC itself is usually chromated (chromium-free passivation is also increasing) to provide temporary protection and enhance paint film adhesion. Phosphating or non-phosphating conversion treatment (such as zirconium and titanium) is sometimes performed before subsequent spraying.
Phosphating: Traditionally used to enhance corrosion resistance and paint film adhesion, but zinc phosphating is not as effective for galvanized sheets as iron phosphating for cold-rolled sheets, and the treatment of zinc-containing wastewater is complicated. Now it is gradually being replaced by more environmentally friendly non-phosphorus conversion films such as zirconium and titanium.
5.In addition to the basic process, what are the auxiliary processes?
Deburring: The burrs produced after cutting and punching must be removed to prevent scratches and affect assembly and appearance. Files, sandpaper, scrapers, deburring machines or vibration grinding can be used (pay attention to the wear of the zinc layer).
Cleaning: Thorough cleaning is required during processing and before painting to remove oil, dust, metal chips, etc. The cleaning agent should be mild to avoid corrosion of the zinc layer (neutral or weakly alkaline pH is preferred).
Leveling: Eliminate deformation of the plate or during processing.