Need to thoroughly remove the workpiece surface oil, oxides and rust, using degreasing solution (chemical de-greasing or water-based cleaning agent) and pickling solution (H₂SO₄/HCl containing corrosion inhibitor) treatment, to ensure that the surface is clean and completely Wetted.
Author: Anna
I. Preparation before operation
Pre-treatment of the workpiece
Need to thoroughly remove the workpiece surface oil, oxides and rust, using degreasing solution (chemical de-greasing or water-based cleaning agent) and pickling solution (H₂SO₄/HCl containing corrosion inhibitor) treatment, to ensure that the surface is clean and completely Wetted.
Rinse well after pickling to avoid contamination of the galvanizing solution by residual acid.
Equipment Inspection and Preheating
Check that the heating system and transmission system of the galvanizing pan are normal, and that the power cord is properly grounded to eliminate the risk of short circuit.
Before starting the galvanizing pot, it should be preheated according to the heating curve, and the temperature should not be increased more than 10℃ per hour to prevent the equipment from being damaged by thermal stress.
II. The galvanizing process control
Temperature management
Zinc liquid temperature is strictly controlled at 445 ~ 460 ℃, keep 435 ± 5 ℃ when shutdown insulation, to avoid the temperature is too high resulting in increased zinc slag or workpiece deformation.
Furnace temperature should be ≥750℃, and the heating surface should be uniform, to prevent local high temperature corrosion of the zinc pot.
Optimization of dipping and plating parameters
The dipping and plating time is usually 0.5~1.5 minutes, and the temperature is 450~470℃, which is too short to lead to uneven plating, and too long to increase iron loss and zinc consumption.
The workpiece should be dried and preheated to 120~180℃ before immersing into the zinc solution to avoid sudden heat deformation or zinc explosion.
Zinc liquid and coating maintenance
The thickness of zinc slag at the bottom of the zinc liquid is ≤150mm, which needs to be cleaned up in time; the liquid surface needs to be covered with heating surface to avoid the formation of high temperature corrosion zone.
Adding pure aluminum (0.01~0.02%) can improve the fluidity of the zinc liquid, reduce the plating layer hanging and wrinkled skin.
III. Safety and Maintenance
Operational Safety Regulations
It is prohibited to touch the high temperature parts (e.g. galvanized pots, conveyor belts) during operation, and wear protective equipment to prevent burns.
Keep clean around the equipment, strictly prohibit stacking of flammable materials, and regularly check the fire and explosion prevention measures.
Equipment Maintenance
Stop the furnace for maintenance every 12 months to repair the corroded parts of the zinc pot. When stopping the furnace, it is necessary to pump zinc or pre-expansion treatment to prevent damage by thermal expansion.
Regularly lubricate bearings and gears, and replace worn parts; clean pipes and water tanks, and keep equipment dry and ventilated.
IV. QUALITY AND EFFICIENCY ASSURANCE
PLATING INSPECTION
Check the thickness, uniformity and adhesion of zinc layer after plating, abnormal situation requires temperature adjustment or dip plating time.
Production management
Control the ratio of production volume to zinc pot volume, keep the heat input stable and avoid overload operation.
Configuration of high-precision temperature control instrumentation, real-time monitoring and recording data to ensure process stability.
Hot-dip galvanizing equipment needs to focus on pretreatment cleanliness, precise temperature control, zinc maintenance and equipment overhaul. Through standardized operation (e.g., temperature ≤ 460°C), regular maintenance (e.g., 12-month furnace shutdown for maintenance) and strict safety measures (e.g., fire and explosion prevention), the quality of the coating can be guaranteed and the life of the equipment can be extended.