- All
- Product Name
- Product Keyword
- Product Model
- Product Summary
- Product Description
- Multi Field Search
English
 |
| Quantity: | |
|---|---|
The electro-galvanizing (electroplating Zn) and hot-dip galvanizing (commonly known as hot-dip zinc) production lines are two core equipment types for zinc coating and corrosion protection of metal workpieces, adaptable to various materials, specifications, and corrosion resistance requirements. The electro-galvanizing production line utilizes electrolysis to achieve zinc layer deposition, emphasizing thin coatings, high precision, and aesthetic appeal, suitable for small and medium-sized precision workpieces. The hot-dip galvanizing production line employs high-temperature molten zinc immersion to form thick coatings, focusing on strong corrosion resistance, high wear resistance, and long-term durability, ideal for large structural components and outdoor applications. Both production lines adopt a three-stage layout of "pre-treatment-core coating-post-treatment," integrated with automated transfer and control systems to enable continuous production. They cover mainstream substrates such as carbon steel and low-alloy steel, with extensive applications in construction, automotive, hardware, power, and related industries.
The electro-galvanizing production line achieves an annual capacity of 50,000-100,000 tons per line, with a coating thickness of 5-20μm and a processing speed of 1-3m/min. The electrothermal zinc production line has an annual capacity of 30,000-80,000 tons per line, producing coatings 50-150μm thick with a dipping cycle of 30-120 seconds per piece. Customizable single-cell or continuous layouts are available to accommodate various production scales based on workpiece dimensions and capacity requirements.
- Feed conveying line: Equipped with belt/chain conveyors, compatible with workpiece dimensions (length 50-3000mm, width 50-1000mm, weight ≤50kg), operating speed 0.5-3m/min, featuring automatic positioning and material distribution devices with ±2mm repeat positioning accuracy to prevent workpiece stacking collisions.
- Pre-degreasing tank: Material: PP/FRP (thickness ≥15mm), capacity: 8-12m³, temperature: 40-50℃, NaOH concentration: 3-5%. Process: Ultrasonic-assisted spray agitation for 2-3 minutes to remove surface oil contaminants and prevent coating adhesion issues.
- Main degreasing tank: Connected in series with the pre-degreasing tank, with NaOH concentration of 5-8%, temperature of 50-60°C, and treatment time of 3-5 minutes to enhance degreasing efficiency. The tank is equipped with a level gauge and temperature sensor, featuring automatic liquid replenishment and temperature control, with a level fluctuation of ≤±50 mm.
- Pickling tank: Made of PP plate (thickness ≥20mm), with hydrochloric acid concentration of 10-15% and temperature ranging from room temperature to-40℃. The treatment duration is 2-4 minutes to remove surface scale and corrosion from the workpiece. Equipped with an acid circulation pump (flow rate 30-50m³/h) to achieve turbulent acid flow and enhance pickling uniformity.
- Neutralization and Water Washing Tank: 3-stage series countercurrent rinsing, with a 2-3% Na₂CO₃ concentration in the neutralization tank and pH controlled at 7-8, treatment time 1-2 minutes; the final rinse water conductivity in the washing tank should be ≤50μS/cm to remove residual acid solution and impurities, preventing pinholes and pitting in the plating layer.
- Galvanized tank: The main body is a steel tank lined with acid-resistant rubber (thickness ≥10mm), with a capacity of 15-25m³. The plating solution is an acidic zinc plating solution (ZnCl₂ 100-150g/L, NH₄Cl 200-250g/L), maintained at a temperature of 20-35℃ and pH 4.0-5.0. An air agitation system combined with a cathode moving device is employed to enhance coating uniformity.
- Electrode assembly: The anode is constructed from pure zinc plates (purity ≥99.99%), with an anode plate spacing of 100-200mm arranged according to workpiece dimensions. The cathode holder, made of brass/stainless steel, supports the workpiece and facilitates electrical conduction. The current density is maintained at 10-20A/dm², with the coating thickness precisely regulated by current density and time.
- Rectifier: High-frequency switching rectifier with output current 0-1000A and voltage 0-20V, featuring ±1% voltage regulation accuracy and ≤0.1s response time. It automatically adjusts current parameters based on workpiece specifications to ensure uniform coating thickness (deviation ≤±1μm).
- Plating solution filtration and purification: Utilizing a precision filter (with a filtration accuracy of 5μm) at a flow rate of 20-40m³/h to remove suspended impurities from the plating solution; equipped with an electroplating wastewater treatment system to recover zinc ions from the plating solution, ensuring the treated wastewater meets discharge standards (pH 6-9, Zn²⁺ ≤0.5mg/L).
- Passivation tank: Made of PP board, using chromate passivation solution (CrO₃ 5-10g/L) or chromium-free passivation solution (Zr/Ti series). Operated at room temperature for 30-60 seconds to form a dense passivation film on the zinc layer, enhancing corrosion resistance (neutral salt spray test ≥96 hours).
- Drying device: Hot air drying tunnel with temperature 60-80℃, air velocity 1-2m/s, drying time 1-2min, surface moisture content of workpiece ≤0.1%, preventing post-drying rusting, ensuring uniform gloss of the plating layer without sagging or color difference.
- Export material cutting and inspection line: Utilizes belt conveyors + manual cutting, equipped with coating thickness gauges (accuracy ±0.1μm) and adhesion testers to automatically inspect coating thickness and adhesion. Non-conforming products are automatically sorted, while qualified workpieces are stored in the warehouse.
- PLC Control System: Equipped with Siemens S7-1200/S7-1500 series, it coordinates all-line equipment for automated regulation of plating solution concentration, temperature, and current density. The system stores over 100 process parameters and supports rapid switching of workpiece specifications.
- Online monitoring system: Real-time monitoring of plating solution concentration, pH value, temperature, current, and voltage, with automatic data recording and upload to the central control room. Supports remote monitoring and historical data traceability, with fault alarm accuracy ≥99%.
- Safety interlocks: overfill/over-temperature alarms for plating tanks, automatic shutdown upon electroplating solution leakage, and emergency power cut for personnel entering hazardous zones, ensuring production safety.
- Coating parameters: thickness 5-20μm, adhesion (scratch test) ≥ grade 1, surface roughness Ra ≤ 1.6μm, neutral salt spray test (after passivation) ≥ 96h.
- Plating solution control: Acidic zinc plating solution (ZnCl₂ 100-150g/L, NH₄Cl 200-250g/L, pH 4.0-5.0, temperature 20-35℃). Conduct weekly concentration tests 1-2 times and replenish chemicals promptly to prevent solution aging.
- Current control: Maintain current density at 10-20A/dm², adjustable based on workpiece area and coating thickness, with electroplating duration of 1-5 minutes to ensure uniform and defect-free coating.
- Pre-treatment control: Ensure the workpiece surface is free of oxide scale and corrosion after pickling, and maintain the conductivity ≤50μS/cm after water washing to prevent residual impurities from causing pinholes or delamination in the coating.
- Material handling equipment: Utilizes gantry crane/hoist (5-50t lifting capacity) with specialized lifting devices (hooks/beam), compatible with workpiece dimensions (length 1-12m, width 0.5-3m, maximum weight ≤50t), operating at 0.1-0.5m/s, ensuring precise transfer to the pre-treatment area.
- De-oiling tank: Made of Q235 steel with acid-resistant rubber lining, capacity 50-100m³, operating temperature 60-80℃, NaOH concentration 8-12%. Steam heating combined with mechanical stirring is employed, with a treatment duration of 10-20 minutes to remove surface oil and grease from workpieces, ensuring optimal plating adhesion.
- Pickling tank: Material: PP/FRP (thickness ≥25mm), Hydrochloric acid concentration: 15-20%, Temperature: 40-50℃, Treatment time: 15-30min. This process removes surface scale and rust from workpieces. Large workpieces are equipped with a stirring device to ensure uniform pickling and prevent localized under-pickling.
- Plating bath: Made of PP board, using ZnCl₂-NH₄Cl mixed solution (ZnCl₂ 300-400g/L, NH₄Cl 100-150g/L) at 80-90℃ for 1-3 minutes to form a protective film on the workpiece surface, preventing pre-oxidation before zinc immersion and enhancing zinc layer adhesion.
- Water wash tank: Perform two-stage countercurrent rinsing at room temperature for 5-10 minutes to remove residual pickling and plating solutions from workpiece surfaces, preventing contamination of zinc bath by introduced residues.
- Galvanized pot: The main body is made of heat-resistant steel (Q345R + heat-resistant alloy lining), with a capacity of 100-500 m³, capable of holding molten zinc liquid (weight 50-250 t). The temperature is controlled at 445-460°C, using natural gas/electric heating with a heating power of 50-200 kW, and the temperature fluctuation is ≤±5°C.
- Zinc solution stirring and purification: Equipped with a mechanical stirring device (stirring speed 10-30 rpm) to prevent zinc solution stratification and oxidation; employs a zinc solution filter to remove Fe-Zn alloy residues (float residue, bottom residue) from the zinc solution, ensuring zinc solution purity ≥99.9%, thereby avoiding slag inclusion defects in the coating.
- Dip coating transfer system: Utilizes a overhead crane with an automated dip coating mechanism to control the workpiece dipping speed (0.5-1 m/min) and dipping duration (30-120 s), ensuring complete immersion in molten zinc and uniform coating. The system then elevates the workpiece at a speed of 1-2 m/min and is equipped with a molten zinc collection tank to recover the zinc liquid carried away by the workpiece.
- Zinc slag treatment device: Automatic scraper for periodic cleaning of floating slag on the surface of galvanizing pot. The slag is cooled and crushed to recover zinc resources, achieving a zinc recovery rate of ≥95% and reducing raw material loss.
- Cooling system: A combined air-water cooling method is employed. After plating, the workpiece undergoes 1-2 minutes of air cooling (3-5 m/s) followed by 3-5 minutes in a water bath (20-40°C). The final temperature is maintained below 60°C to prevent zinc layer oxidation and discoloration caused by high temperatures.
- Finishing and Cleaning: Equipped with manual/mechanical finishing tools to remove zinc nodules, burrs, and sagging on the workpiece surface, as well as to clean residual zinc liquid from the internal cavity, ensuring dimensional accuracy and surface quality of the workpiece.
- Passivation/encapsulation treatment (optional): Apply chromium-free passivation solution for 1-2 minutes to enhance the corrosion resistance of the zinc coating; or perform encapsulation treatment to improve the gloss and stain resistance of the coating, with a neutral salt spray test duration of ≥500 hours.
- Export inspection and material handling: Equipped with coating thickness gauges (accuracy ±1μm) and ultrasonic flaw detectors to inspect coating thickness and adhesion strength; qualified workpieces are transferred to the material handling area by overhead crane for classified storage, while non-conforming items undergo rework processing.
- PLC control system: Equipped with Siemens S7-1500 series, it regulates parameters including zinc pot temperature, dipping duration, and cooling rate. The system supports automated processes such as dipping, residue scraping, and zinc liquid replenishment, minimizing manual intervention and boosting production efficiency.
- Temperature Monitoring System: Multiple temperature sensors are installed inside the galvanized pot to monitor the zinc liquid temperature in real time. The heating system automatically starts and stops to ensure the temperature remains stable at 445-460°C.
- Safety interlocks: over-temperature/over-level alarms for galvanized pots, gas leakage-linked gas cutoff, high cooling water temperature alarms, and emergency stop buttons, ensuring safety during high-temperature operations.
- Coating parameters: Thickness 50-150μm, adhesion (hammer test) without peeling, coating uniformity deviation ≤±10μm, neutral salt spray test (after passivation) ≥500h.
- Zinc bath control: Maintain zinc bath temperature at 445-460°C, with purity ≥99.9% and Fe content ≤0.05%. Perform periodic zinc bath composition analysis, replenish zinc ingots as needed, and clean zinc slag to prevent zinc bath aging.
- Dip coating control: The dipping time is 30-120 seconds, adjusted according to the thickness of the workpiece, with shorter duration for thin workpieces and extended duration for thick workpieces; the dipping speed should be uniform to avoid collision between the workpiece and the zinc pot wall, preventing damage to the zinc coating.
- Pre-treatment control: The plating bath temperature should be maintained at 80-90°C with stable concentration. After plating, the workpiece surface must be free of moisture and impurities to prevent zinc ash formation from zinc liquid, which could compromise coating quality.
| Comparison Dimension | Galvanizing Production Line Equipment | Electrothermal Zinc (Hot-Dip Galvanizing) Production Line Equipment | | ---- | ---- | ---- | | Core Principle | Electrolytic Deposition (Zinc Ion Reduction Deposition) | High-Temperature Immersion (Workpiece Immersion in Molten Zinc Liquid) | | Coating Thickness | 5-20μm (Thin Coating) | 50-150μm (Thick Coating) | | Corrosion Resistance | Moderate (Neutral Salt Spray ≥96h) | Excellent (Neutral Salt Spray ≥500h) | | Applicable Workpieces | Small to Medium Precision Workpieces (Weight ≤50kg) | Large Structural Components (Weight ≤50t) | | Production Efficiency | High (1-3m/min) | Moderate (30-120s/unit) | | Equipment Cost | Mid-to-Low (50-2 million RMB per Line) | Mid-to-High (200-10 million RMB per Line) | | Environmental Requirements | Electroplating Wastewater Treatment Required, No Significant Exhaust Gas | Zinc Fume and Gas Exhaust Treatment Required, High Environmental Investment | | Appearance Quality | Uniform Gloss, High Aesthetics | Slightly Rough Appearance, Optimizeable Through Post-Treatment | | Service Life | Coating Life 5-10 years (Indoor) | Coating Life 15-30 years (Outdoor) |
- Daily inspection: Check the liquid level, chemical concentration, and temperature of each tank before daily startup, confirm that the conveying equipment, pump sets, and valves are operating normally, and promptly address any leaks or abnormalities.
- Chemical Management: Prepare degreasing solution, pickling solution, and plating solution strictly in accordance with process requirements. Regularly test concentrations and replenish promptly to prevent chemical degradation from affecting treatment efficacy. Store hazardous chemicals (acids, alkalis, zinc ingots) separately and implement appropriate protective measures.
- Environmental compliance: Ensure the normal operation of wastewater and exhaust gas treatment facilities to achieve emission standards; regularly clean tank sediment and filter impurities, recover useful resources (zinc ions, zinc slag), and reduce environmental risks.
- Safety Protection: Operators must wear acid/heat-resistant gloves, face shields, and protective clothing. Violations of operating procedures are strictly prohibited. Warning signs shall be installed in high-temperature and high-pressure areas, and unauthorized personnel are forbidden to enter.
- Plating solution maintenance: Filter the plating solution 1-2 times per week to remove suspended impurities; replace part of the plating solution once per month to prevent accumulation of heavy metal ions, which may lead to coating defects.
- Electrode maintenance: Regularly inspect the wear of anode zinc plates and replace them promptly; clean the oxide layer and coating on the cathode holder surface to ensure good conductivity and prevent uneven coating due to poor contact.
- Current control: Strictly prohibit operation at overcurrent density to prevent coating scorching and peeling; precisely adjust current parameters according to workpiece specifications, and record process data for traceability.
- Maintenance of galvanized pots: Regularly inspect the wear condition of the pot lining, and promptly repair any damages to prevent zinc liquid leakage; clean the pot bottom residue once a month to avoid zinc residue accumulation that may affect the purity of the zinc liquid.
- Temperature control: Strictly maintain the zinc bath temperature within 445-460°C to prevent overheating-induced zinc oxidation, which generates excessive zinc ash. Conversely, low temperatures may result in insufficient zinc layer thickness and poor adhesion.
- Dip coating procedure: The workpiece must be completely dry prior to dipping to prevent moisture ingress that could cause zinc liquid splashing and lead to safety incidents; maintain uniform dipping speed to avoid workpiece collision with the pot wall, which may damage both the galvanizing pot and the workpiece.
- Electro-galvanizing production line: Suitable for automotive components (bolts, nuts, stamped parts), hardware products (door/window fittings, tools), electronic components, and precision instrument accessories, requiring thin coatings, high precision, and aesthetically pleasing appearance.
- Electric zinc production line: Suitable for construction steel structures (I-beams, angle steels, bolts), power equipment (utility poles, supports), transportation facilities (guardrails, streetlight poles), and large machinery components, requiring strong corrosion resistance and long-term durability for outdoor/heavy-duty applications.
- Capacity matching: Small hardware factories (annual capacity ≤50,000 tons) may opt for electro-galvanizing production lines; large steel structure factories (annual capacity ≥30,000 tons) may choose electrothermal zinc production lines, with single-cell/continuous layout customized according to workpiece dimensions.
- Cost considerations: For initial budget constraints and smaller workpieces, electro-galvanizing equipment is recommended; for long-term outdoor use with high corrosion resistance requirements, electrothermal zinc equipment is preferable, despite its higher initial investment, it offers lower maintenance costs and longer service life.
- Environmental requirements: The region enforces stringent environmental controls, necessitating prioritized installation of wastewater and exhaust gas treatment facilities. For electro-galvanizing, emphasis is placed on electroplating wastewater recovery, while for electrothermal zinc production, focus is on zinc mist and gas exhaust treatment.
The electro-galvanizing (electroplating Zn) and hot-dip galvanizing (commonly known as hot-dip zinc) production lines are two core equipment types for zinc coating and corrosion protection of metal workpieces, adaptable to various materials, specifications, and corrosion resistance requirements. The electro-galvanizing production line utilizes electrolysis to achieve zinc layer deposition, emphasizing thin coatings, high precision, and aesthetic appeal, suitable for small and medium-sized precision workpieces. The hot-dip galvanizing production line employs high-temperature molten zinc immersion to form thick coatings, focusing on strong corrosion resistance, high wear resistance, and long-term durability, ideal for large structural components and outdoor applications. Both production lines adopt a three-stage layout of "pre-treatment-core coating-post-treatment," integrated with automated transfer and control systems to enable continuous production. They cover mainstream substrates such as carbon steel and low-alloy steel, with extensive applications in construction, automotive, hardware, power, and related industries.
The electro-galvanizing production line achieves an annual capacity of 50,000-100,000 tons per line, with a coating thickness of 5-20μm and a processing speed of 1-3m/min. The electrothermal zinc production line has an annual capacity of 30,000-80,000 tons per line, producing coatings 50-150μm thick with a dipping cycle of 30-120 seconds per piece. Customizable single-cell or continuous layouts are available to accommodate various production scales based on workpiece dimensions and capacity requirements.
- Feed conveying line: Equipped with belt/chain conveyors, compatible with workpiece dimensions (length 50-3000mm, width 50-1000mm, weight ≤50kg), operating speed 0.5-3m/min, featuring automatic positioning and material distribution devices with ±2mm repeat positioning accuracy to prevent workpiece stacking collisions.
- Pre-degreasing tank: Material: PP/FRP (thickness ≥15mm), capacity: 8-12m³, temperature: 40-50℃, NaOH concentration: 3-5%. Process: Ultrasonic-assisted spray agitation for 2-3 minutes to remove surface oil contaminants and prevent coating adhesion issues.
- Main degreasing tank: Connected in series with the pre-degreasing tank, with NaOH concentration of 5-8%, temperature of 50-60°C, and treatment time of 3-5 minutes to enhance degreasing efficiency. The tank is equipped with a level gauge and temperature sensor, featuring automatic liquid replenishment and temperature control, with a level fluctuation of ≤±50 mm.
- Pickling tank: Made of PP plate (thickness ≥20mm), with hydrochloric acid concentration of 10-15% and temperature ranging from room temperature to-40℃. The treatment duration is 2-4 minutes to remove surface scale and corrosion from the workpiece. Equipped with an acid circulation pump (flow rate 30-50m³/h) to achieve turbulent acid flow and enhance pickling uniformity.
- Neutralization and Water Washing Tank: 3-stage series countercurrent rinsing, with a 2-3% Na₂CO₃ concentration in the neutralization tank and pH controlled at 7-8, treatment time 1-2 minutes; the final rinse water conductivity in the washing tank should be ≤50μS/cm to remove residual acid solution and impurities, preventing pinholes and pitting in the plating layer.
- Galvanized tank: The main body is a steel tank lined with acid-resistant rubber (thickness ≥10mm), with a capacity of 15-25m³. The plating solution is an acidic zinc plating solution (ZnCl₂ 100-150g/L, NH₄Cl 200-250g/L), maintained at a temperature of 20-35℃ and pH 4.0-5.0. An air agitation system combined with a cathode moving device is employed to enhance coating uniformity.
- Electrode assembly: The anode is constructed from pure zinc plates (purity ≥99.99%), with an anode plate spacing of 100-200mm arranged according to workpiece dimensions. The cathode holder, made of brass/stainless steel, supports the workpiece and facilitates electrical conduction. The current density is maintained at 10-20A/dm², with the coating thickness precisely regulated by current density and time.
- Rectifier: High-frequency switching rectifier with output current 0-1000A and voltage 0-20V, featuring ±1% voltage regulation accuracy and ≤0.1s response time. It automatically adjusts current parameters based on workpiece specifications to ensure uniform coating thickness (deviation ≤±1μm).
- Plating solution filtration and purification: Utilizing a precision filter (with a filtration accuracy of 5μm) at a flow rate of 20-40m³/h to remove suspended impurities from the plating solution; equipped with an electroplating wastewater treatment system to recover zinc ions from the plating solution, ensuring the treated wastewater meets discharge standards (pH 6-9, Zn²⁺ ≤0.5mg/L).
- Passivation tank: Made of PP board, using chromate passivation solution (CrO₃ 5-10g/L) or chromium-free passivation solution (Zr/Ti series). Operated at room temperature for 30-60 seconds to form a dense passivation film on the zinc layer, enhancing corrosion resistance (neutral salt spray test ≥96 hours).
- Drying device: Hot air drying tunnel with temperature 60-80℃, air velocity 1-2m/s, drying time 1-2min, surface moisture content of workpiece ≤0.1%, preventing post-drying rusting, ensuring uniform gloss of the plating layer without sagging or color difference.
- Export material cutting and inspection line: Utilizes belt conveyors + manual cutting, equipped with coating thickness gauges (accuracy ±0.1μm) and adhesion testers to automatically inspect coating thickness and adhesion. Non-conforming products are automatically sorted, while qualified workpieces are stored in the warehouse.
- PLC Control System: Equipped with Siemens S7-1200/S7-1500 series, it coordinates all-line equipment for automated regulation of plating solution concentration, temperature, and current density. The system stores over 100 process parameters and supports rapid switching of workpiece specifications.
- Online monitoring system: Real-time monitoring of plating solution concentration, pH value, temperature, current, and voltage, with automatic data recording and upload to the central control room. Supports remote monitoring and historical data traceability, with fault alarm accuracy ≥99%.
- Safety interlocks: overfill/over-temperature alarms for plating tanks, automatic shutdown upon electroplating solution leakage, and emergency power cut for personnel entering hazardous zones, ensuring production safety.
- Coating parameters: thickness 5-20μm, adhesion (scratch test) ≥ grade 1, surface roughness Ra ≤ 1.6μm, neutral salt spray test (after passivation) ≥ 96h.
- Plating solution control: Acidic zinc plating solution (ZnCl₂ 100-150g/L, NH₄Cl 200-250g/L, pH 4.0-5.0, temperature 20-35℃). Conduct weekly concentration tests 1-2 times and replenish chemicals promptly to prevent solution aging.
- Current control: Maintain current density at 10-20A/dm², adjustable based on workpiece area and coating thickness, with electroplating duration of 1-5 minutes to ensure uniform and defect-free coating.
- Pre-treatment control: Ensure the workpiece surface is free of oxide scale and corrosion after pickling, and maintain the conductivity ≤50μS/cm after water washing to prevent residual impurities from causing pinholes or delamination in the coating.
- Material handling equipment: Utilizes gantry crane/hoist (5-50t lifting capacity) with specialized lifting devices (hooks/beam), compatible with workpiece dimensions (length 1-12m, width 0.5-3m, maximum weight ≤50t), operating at 0.1-0.5m/s, ensuring precise transfer to the pre-treatment area.
- De-oiling tank: Made of Q235 steel with acid-resistant rubber lining, capacity 50-100m³, operating temperature 60-80℃, NaOH concentration 8-12%. Steam heating combined with mechanical stirring is employed, with a treatment duration of 10-20 minutes to remove surface oil and grease from workpieces, ensuring optimal plating adhesion.
- Pickling tank: Material: PP/FRP (thickness ≥25mm), Hydrochloric acid concentration: 15-20%, Temperature: 40-50℃, Treatment time: 15-30min. This process removes surface scale and rust from workpieces. Large workpieces are equipped with a stirring device to ensure uniform pickling and prevent localized under-pickling.
- Plating bath: Made of PP board, using ZnCl₂-NH₄Cl mixed solution (ZnCl₂ 300-400g/L, NH₄Cl 100-150g/L) at 80-90℃ for 1-3 minutes to form a protective film on the workpiece surface, preventing pre-oxidation before zinc immersion and enhancing zinc layer adhesion.
- Water wash tank: Perform two-stage countercurrent rinsing at room temperature for 5-10 minutes to remove residual pickling and plating solutions from workpiece surfaces, preventing contamination of zinc bath by introduced residues.
- Galvanized pot: The main body is made of heat-resistant steel (Q345R + heat-resistant alloy lining), with a capacity of 100-500 m³, capable of holding molten zinc liquid (weight 50-250 t). The temperature is controlled at 445-460°C, using natural gas/electric heating with a heating power of 50-200 kW, and the temperature fluctuation is ≤±5°C.
- Zinc solution stirring and purification: Equipped with a mechanical stirring device (stirring speed 10-30 rpm) to prevent zinc solution stratification and oxidation; employs a zinc solution filter to remove Fe-Zn alloy residues (float residue, bottom residue) from the zinc solution, ensuring zinc solution purity ≥99.9%, thereby avoiding slag inclusion defects in the coating.
- Dip coating transfer system: Utilizes a overhead crane with an automated dip coating mechanism to control the workpiece dipping speed (0.5-1 m/min) and dipping duration (30-120 s), ensuring complete immersion in molten zinc and uniform coating. The system then elevates the workpiece at a speed of 1-2 m/min and is equipped with a molten zinc collection tank to recover the zinc liquid carried away by the workpiece.
- Zinc slag treatment device: Automatic scraper for periodic cleaning of floating slag on the surface of galvanizing pot. The slag is cooled and crushed to recover zinc resources, achieving a zinc recovery rate of ≥95% and reducing raw material loss.
- Cooling system: A combined air-water cooling method is employed. After plating, the workpiece undergoes 1-2 minutes of air cooling (3-5 m/s) followed by 3-5 minutes in a water bath (20-40°C). The final temperature is maintained below 60°C to prevent zinc layer oxidation and discoloration caused by high temperatures.
- Finishing and Cleaning: Equipped with manual/mechanical finishing tools to remove zinc nodules, burrs, and sagging on the workpiece surface, as well as to clean residual zinc liquid from the internal cavity, ensuring dimensional accuracy and surface quality of the workpiece.
- Passivation/encapsulation treatment (optional): Apply chromium-free passivation solution for 1-2 minutes to enhance the corrosion resistance of the zinc coating; or perform encapsulation treatment to improve the gloss and stain resistance of the coating, with a neutral salt spray test duration of ≥500 hours.
- Export inspection and material handling: Equipped with coating thickness gauges (accuracy ±1μm) and ultrasonic flaw detectors to inspect coating thickness and adhesion strength; qualified workpieces are transferred to the material handling area by overhead crane for classified storage, while non-conforming items undergo rework processing.
- PLC control system: Equipped with Siemens S7-1500 series, it regulates parameters including zinc pot temperature, dipping duration, and cooling rate. The system supports automated processes such as dipping, residue scraping, and zinc liquid replenishment, minimizing manual intervention and boosting production efficiency.
- Temperature Monitoring System: Multiple temperature sensors are installed inside the galvanized pot to monitor the zinc liquid temperature in real time. The heating system automatically starts and stops to ensure the temperature remains stable at 445-460°C.
- Safety interlocks: over-temperature/over-level alarms for galvanized pots, gas leakage-linked gas cutoff, high cooling water temperature alarms, and emergency stop buttons, ensuring safety during high-temperature operations.
- Coating parameters: Thickness 50-150μm, adhesion (hammer test) without peeling, coating uniformity deviation ≤±10μm, neutral salt spray test (after passivation) ≥500h.
- Zinc bath control: Maintain zinc bath temperature at 445-460°C, with purity ≥99.9% and Fe content ≤0.05%. Perform periodic zinc bath composition analysis, replenish zinc ingots as needed, and clean zinc slag to prevent zinc bath aging.
- Dip coating control: The dipping time is 30-120 seconds, adjusted according to the thickness of the workpiece, with shorter duration for thin workpieces and extended duration for thick workpieces; the dipping speed should be uniform to avoid collision between the workpiece and the zinc pot wall, preventing damage to the zinc coating.
- Pre-treatment control: The plating bath temperature should be maintained at 80-90°C with stable concentration. After plating, the workpiece surface must be free of moisture and impurities to prevent zinc ash formation from zinc liquid, which could compromise coating quality.
| Comparison Dimension | Galvanizing Production Line Equipment | Electrothermal Zinc (Hot-Dip Galvanizing) Production Line Equipment | | ---- | ---- | ---- | | Core Principle | Electrolytic Deposition (Zinc Ion Reduction Deposition) | High-Temperature Immersion (Workpiece Immersion in Molten Zinc Liquid) | | Coating Thickness | 5-20μm (Thin Coating) | 50-150μm (Thick Coating) | | Corrosion Resistance | Moderate (Neutral Salt Spray ≥96h) | Excellent (Neutral Salt Spray ≥500h) | | Applicable Workpieces | Small to Medium Precision Workpieces (Weight ≤50kg) | Large Structural Components (Weight ≤50t) | | Production Efficiency | High (1-3m/min) | Moderate (30-120s/unit) | | Equipment Cost | Mid-to-Low (50-2 million RMB per Line) | Mid-to-High (200-10 million RMB per Line) | | Environmental Requirements | Electroplating Wastewater Treatment Required, No Significant Exhaust Gas | Zinc Fume and Gas Exhaust Treatment Required, High Environmental Investment | | Appearance Quality | Uniform Gloss, High Aesthetics | Slightly Rough Appearance, Optimizeable Through Post-Treatment | | Service Life | Coating Life 5-10 years (Indoor) | Coating Life 15-30 years (Outdoor) |
- Daily inspection: Check the liquid level, chemical concentration, and temperature of each tank before daily startup, confirm that the conveying equipment, pump sets, and valves are operating normally, and promptly address any leaks or abnormalities.
- Chemical Management: Prepare degreasing solution, pickling solution, and plating solution strictly in accordance with process requirements. Regularly test concentrations and replenish promptly to prevent chemical degradation from affecting treatment efficacy. Store hazardous chemicals (acids, alkalis, zinc ingots) separately and implement appropriate protective measures.
- Environmental compliance: Ensure the normal operation of wastewater and exhaust gas treatment facilities to achieve emission standards; regularly clean tank sediment and filter impurities, recover useful resources (zinc ions, zinc slag), and reduce environmental risks.
- Safety Protection: Operators must wear acid/heat-resistant gloves, face shields, and protective clothing. Violations of operating procedures are strictly prohibited. Warning signs shall be installed in high-temperature and high-pressure areas, and unauthorized personnel are forbidden to enter.
- Plating solution maintenance: Filter the plating solution 1-2 times per week to remove suspended impurities; replace part of the plating solution once per month to prevent accumulation of heavy metal ions, which may lead to coating defects.
- Electrode maintenance: Regularly inspect the wear of anode zinc plates and replace them promptly; clean the oxide layer and coating on the cathode holder surface to ensure good conductivity and prevent uneven coating due to poor contact.
- Current control: Strictly prohibit operation at overcurrent density to prevent coating scorching and peeling; precisely adjust current parameters according to workpiece specifications, and record process data for traceability.
- Maintenance of galvanized pots: Regularly inspect the wear condition of the pot lining, and promptly repair any damages to prevent zinc liquid leakage; clean the pot bottom residue once a month to avoid zinc residue accumulation that may affect the purity of the zinc liquid.
- Temperature control: Strictly maintain the zinc bath temperature within 445-460°C to prevent overheating-induced zinc oxidation, which generates excessive zinc ash. Conversely, low temperatures may result in insufficient zinc layer thickness and poor adhesion.
- Dip coating procedure: The workpiece must be completely dry prior to dipping to prevent moisture ingress that could cause zinc liquid splashing and lead to safety incidents; maintain uniform dipping speed to avoid workpiece collision with the pot wall, which may damage both the galvanizing pot and the workpiece.
- Electro-galvanizing production line: Suitable for automotive components (bolts, nuts, stamped parts), hardware products (door/window fittings, tools), electronic components, and precision instrument accessories, requiring thin coatings, high precision, and aesthetically pleasing appearance.
- Electric zinc production line: Suitable for construction steel structures (I-beams, angle steels, bolts), power equipment (utility poles, supports), transportation facilities (guardrails, streetlight poles), and large machinery components, requiring strong corrosion resistance and long-term durability for outdoor/heavy-duty applications.
- Capacity matching: Small hardware factories (annual capacity ≤50,000 tons) may opt for electro-galvanizing production lines; large steel structure factories (annual capacity ≥30,000 tons) may choose electrothermal zinc production lines, with single-cell/continuous layout customized according to workpiece dimensions.
- Cost considerations: For initial budget constraints and smaller workpieces, electro-galvanizing equipment is recommended; for long-term outdoor use with high corrosion resistance requirements, electrothermal zinc equipment is preferable, despite its higher initial investment, it offers lower maintenance costs and longer service life.
- Environmental requirements: The region enforces stringent environmental controls, necessitating prioritized installation of wastewater and exhaust gas treatment facilities. For electro-galvanizing, emphasis is placed on electroplating wastewater recovery, while for electrothermal zinc production, focus is on zinc mist and gas exhaust treatment.
