Batch hot-dip galvanizing process

Hot-dip galvanizing is a surface chemical heat treatment process in which clean steel is immersed in molten zinc or zinc alloy to obtain a zinc-diffused layer. Steel strips, steel wires, etc. are galvanized by continuous hot-dip galvanizing. Steel parts (such as steel sections, fasteners and other mechanical parts) are galvanized by batch hot-dip galvanizing. 
The process flow of batch hot-dip galvanizing is: steel parts-degreasing-rust removal-plating agent-drying-hot-dip galvanizing-cooling-passivation-finished product. The main functions of the plating agent are: ① remove the residual iron oxide on the surface of steel; ② improve the wettability of the workpiece and the zinc liquid. The main components of the plating agent are ZnCI2 and NH4CI. After the steel parts enter the zinc solution through the assisted plating, the following reactions occur: 
NH₄CI==NH₃+HCI 
FeO +2HCI==FeCI₂+H₂0 
Fe₂O+6HCI==2FeCl₃ +3H₂O 
Zn+FeCI₂==ZnCI₂+Fe 
3Zn+2FeCI₃==3ZnCI₂ +2Fe 
In the zinc solution, the iron and zinc on the surface of the steel parts diffuse to form a diffusion layer, the main components of which are: η phase (Fe5Zn26), δ phase (FeZn17), ζ phase {(FeZn13). When the steel parts are taken out of the zinc solution, the surface is covered with a zinc coating, which is the η phase, and its main components are basically the same as those of the zinc solution. The hot-dip galvanized layer is composed of the above-mentioned diffusion layer and the galvanized layer.

Composition of large-scale intelligent batch hanging plating production line

● Main equipment: pre-treatment (oil removal, rust removal, plating aid) tank; drying furnace; galvanizing pot; zinc pot heating furnace; post-treatment (water washing, passivation) tank. 
● Environmental protection equipment: zinc fume dust collector, zinc fume closed hood; acid mist absorption tower; pre-treatment closed room. 
● Energy-saving equipment: waste heat heating plating aid tank; waste heat heating drying furnace; cold dewatering waste heat heating acid tank. 
● Consumption-reducing equipment: online iron removal equipment for plating aid. 
● Automated logistics: monorail or bridge crane, ground rail car, pit chain transmission mechanism, lifting station, chain transmission stand, fixed stand, hanger and hook. 
● Central automation, information, intelligent control system [composed of host computer (HMI), PLC, field instrument, etc. Among them, the automation system PLC mainly completes communication, data collection, important logic control, etc. The host computer plays a role in centralized monitoring and management. ]

Equipment selection suggestions for large-scale batch hanging plating production line

● The heating furnace can use electricity, natural gas, and liquefied petroleum gas as energy. 
● The length, width, and depth of the zinc pot are determined according to the three-dimensional size and production capacity of the workpiece: the length of the zinc pot is the length of the longest pre-plated workpiece plus 1 meter, the width is the width of the widest pre-plated workpiece plus 0.2 meters, and the depth is length x width x depth x 6.9 ÷ 40 = 1 hour of production capacity. 
● According to the investment, logistics can choose manually operated remote control cranes, semi-automatic logistics systems, and fully automatic logistics systems.

Small intelligent hot-dip galvanizing production line composition

● Main equipment: automatic loading, automatic pre-treatment (oil removal, rust removal, plating assistance); mesh belt (plate chain) drying furnace; high-temperature ceramic galvanizing pot; zinc throwing machine; mesh belt (plate chain) automatic post-treatment (water washing, passivation); mesh belt (plate chain) automatic drying furnace; automatic galvanizing manipulator (robot). 
● Environmental protection equipment: zinc fume dust collector; galvanizing furnace closed room; acid mist absorption tower, pre-treatment closed room. 
● Consumption reduction equipment: online iron removal equipment for plating agent. 
● Central automation, informationization, and intelligent control system (composed of host computer (HMI), PLC, field instruments, etc. Among them, the automation system PLC mainly completes communication, data collection, important logic control, etc. The host computer plays a role in centralized monitoring and management.)

Selection suggestions for equipment for small hot-dip galvanizing production line

● The heating furnace can generally use electricity as energy and adopt a high-temperature ceramic zinc pot. 
● The length, width, and depth of the zinc pot are determined according to the production capacity: length x width x depth x6.9÷15=1 hour production capacity. 
● According to the investment, manual galvanizing operation, manipulator galvanizing operation, and fully automatic robot operation can be selected.

Performance and application of hot-dip galvanizing

Hot-dip galvanizing has good corrosion resistance in various atmospheric environments and is widely used in the surface treatment of outdoor steel structures and mechanical parts. Such as: power transmission and transformation towers, communication tower materials, bridges, large steel components, special-shaped steel components, transportation facilities (high-speed railways, highway guardrails, sound barriers, columns, lamp poles, bridges); fasteners and parts for automobiles and engineering machinery; chemical equipment, oil processing, marine exploration, shipbuilding; agriculture: sprinkler irrigation, heating rooms; construction: water and gas transportation, wire casing, scaffolding, houses; various steel (channel steel, angle steel, steel bar, steel pipe, flat iron) metal products; various small components made of high carbon steel, ductile iron, malleable cast iron, and cast iron (such as power fittings, malleable cast iron parts, fasteners, steel nails). 
The hot-dip galvanized layer also has good corrosion resistance in soil, concrete, and water environments with pH6~pH11 (such as rivers, seawater, and some industrial water). It has been widely used in marine pipelines and parts, offshore drilling platform structural parts, oil extraction pumping pipes, civil and industrial water pipes, and building embedded parts.

Our company can provide the following services

Our company provides high-efficiency, energy-saving, low-consumption, environmentally friendly, highly intelligent batch structural steel hot-dip galvanizing production lines, small-piece hot-dip galvanizing fully automatic production lines, steel pipe hot-dip galvanizing production lines and supporting environmental protection equipment design, manufacturing, installation and commissioning; provides whole plant planning and design; production workshop layout design; energy and power equipment design; operators and managers galvanizing operation process skills, safe operation, workshop management, quality control, energy-saving and consumption reduction measures training, hot-dip galvanizing process technology consultation (from a flat land to the production of qualified products); traditional galvanizing furnace energy saving, consumption reduction, environmental protection, improve efficiency, improve the degree of intelligence (automation), change heating methods, replace energy, quality upgrade and other technical transformation.