Steel wire phosphating can generally be classified into two categories based on the production line configuration:

• Batch (Immersion) Phosphating Line

• Continuous Phosphating Line

The structure of the production line determines the phosphating process and operating conditions.

1. Batch (Immersion) Phosphating Line

Batch phosphating lines are characterized by:

• Steel wire is processed in coil form.

• The wire remains immersed in the phosphating solution for a certain period.

• Sufficient reaction time allows for stable phosphate film formation.

Two common phosphating processes are used.

01 Traditional Medium-Temperature Phosphating

Typical operating temperature: 65–75°C

This is one of the most widely used phosphating processes due to its mature technology and stable coating performance.

Depending on the scale removal method, it can be divided into:

• Acid pickling

• Mechanical descaling

• Shot blasting

02 Low-Temperature Tank-External Phosphating

Typical operating temperature: 50–60°C

This is an emerging phosphating technology that has gained popularity in recent years.

Compared with conventional medium-temperature phosphating, it offers:

• Lower operating temperature

• Reduced energy consumption

  
  

  

2. Continuous Phosphating Line

Continuous phosphating lines feature:

• Continuous wire movement through the production line

• Short reaction time

• High requirements for rapid phosphate film formation

Two common processes are used.

01 Traditional High-Temperature Phosphating

Typical operating temperature: 75–85°C

Main characteristics:

• Fast chemical reaction

• High coating formation efficiency

• Typically combined with acid pickling for scale removal

This remains the conventional phosphating process for many continuous wire production lines.

02 Electrolytic Phosphating

Typical operating temperature: 40–60°C

Electrolytic phosphating is a newer online phosphating technology designed for continuous production.

The descaling method generally depends on the production line configuration:

• Mechanical descaling (commonly used for single-wire lines)

• Acid pickling (commonly used for 28–48 wire multi-wire lines)

Compared with traditional high-temperature continuous phosphating, electrolytic phosphating offers:

• Lower operating temperature

• Different process control principles

• Higher requirements for system integration and process control