1.Why is laser cutting suitable for galvanized coils?
High precision and high quality: Laser cutting achieves extremely high dimensional and contour accuracy, with narrow kerfs, making it ideal for cutting complex and intricate shapes.
Non-contact processing: The laser head does not contact the material, avoiding mechanical stress and preventing scratches on the galvanized surface.
High efficiency and speed: For thin sheets and medium-thickness galvanized coils, laser cutting is very fast, facilitating automated continuous production.
Good cut perpendicularity: With correct parameters, smooth, perpendicular cut surfaces can be obtained.
2.What are the causes and solutions for slag (burrs) forming when cutting galvanized coils?
Reason: The zinc layer melts and vaporizes before the steel. Molten zinc is not easily blown away completely and tends to adhere to the bottom and back of the cut, forming burrs that are difficult to remove.
Solution: Gas Selection and Pressure: Use high-purity, high-pressure oxygen or air as the auxiliary gas. Oxygen reacts exothermically with molten zinc, aiding in its further combustion and removal. High pressure effectively removes slag.
Optimize Cutting Parameters: Precisely adjust laser power, cutting speed, gas pressure, and focal point position. This typically requires higher gas pressure and faster speed than when cutting cold-rolled steel of the same thickness.
3.What are the causes and solutions for zinc vapor and splashing?
Cause: The zinc layer boils and vaporizes rapidly, producing a large amount of zinc vapor and high-energy splashes.
Solutions:
Enhanced Protection: Use high-quality protective lenses and increase replacement frequency.
Adopt Angled Cutting Heads: Or cutting heads with anti-splatter design can effectively prevent splatter from bouncing vertically and contaminating the lenses.
Parameter Optimization: Reasonable power and speed can reduce overburning and splattering.
4.What are the reasons for problems with the quality of the cut surface?
Due to the different physical properties of zinc and steel, the lower part of the cut surface may appear scorched, blackened, or rough.
High-speed cutting with nitrogen: For workpieces requiring a bright, oxidation-free cut, high-pressure nitrogen can be used. Nitrogen is an inert gas that inhibits combustion reactions, resulting in a clean, silvery-white cut surface; however, the gas is relatively expensive.
Focus control: Precisely controlling the focus within the sheet metal or on its surface to achieve optimal cutting results.
5.What are the key points for process control?
Laser Type: Fiber lasers are currently the best choice for cutting thin metal sheets (including galvanized sheets). They offer advantages such as high photoelectric conversion efficiency, fast cutting speed, low energy consumption, and simple maintenance, and are also more adaptable to highly reflective materials.
Auxiliary Gas:
Oxygen: Cost-effective and fast cutting speed. However, the cut will become black and rough due to oxidation, making it suitable for structural parts where the appearance of the cut is not critical.
Nitrogen: Produces oxidation-free, bright, and clean cuts with the best quality. However, it consumes a large amount of gas and is expensive, making it suitable for workpieces with strict appearance requirements.
Air: Lowest operating cost, but the cut will slightly oxidize. Its quality falls between oxygen and nitrogen, making it a compromise between cost and quality.
Parameter Optimization: Optimal parameters must be found through trial cuts. Professional laser cutting operators or programming software will set the appropriate power, speed, gas pressure, and focus position based on the thickness of the sheet and the weight of the zinc layer.