Fin tubes are core components in heat exchange equipment, and their manufacturing process aims to achieve a strong, low-thermal-resistance bond between fins and base tubes, ensuring efficient heat transfer and long-term durability. With the development of industrial technology, fin tube manufacturing has formed various mature processes, covering key technologies such as mechanical bonding, welding, winding, and integral forming. The following explanation focuses on three aspects: core processes, key procedures, and material selection.

 

Based on material properties and operating condition requirements, fin tube manufacturing mainly adopts the following processes:

1. Roll Forming (Mechanical Bonding)

This process is suitable for materials with good ductility such as aluminum and copper. Aluminum strips pass through a specialized rolling mill, where fin rolling and spiral winding are completed simultaneously under the action of dies. Mechanical interlocking between fins and the base tube is achieved through metal plastic deformation without solder, offering high forming efficiency and no joint, making it ideal for mass production in industries like air conditioning.

2. High-Frequency Welding

This is the mainstream process for stainless steel fin tubes. Eddy currents generated by a high-frequency induction coil instantly heat the contact area between fins and the base tube to a molten state (temperature reaching 1300-1500°C), and metallurgical bonding is achieved by applying pressure with pressure wheels. The weld strength can reach over 80% of the base material, with low thermal resistance, suitable for medium-high temperature and high-pressure working conditions, such as in chemical and power industries.

3. Wound Fixing

Metal strips are spirally wound around the outer surface of the base tube and fixed by mechanical pressure, sometimes supplemented with low-temperature welding to enhance stability. This process has lower costs but relatively weaker bonding strength, mostly used in low-temperature or less demanding scenarios.

4. Integral Rolling

Fins are directly rolled on the outer wall of the base tube using a specialized rolling mill, forming a seamless integral structure. This process offers optimal corrosion resistance and structural strength but is costly, or high-pressure special environments.

 

Fin tube manufacturing follows rigorous procedures to ensure quality and performance:

1. Raw Material Pretreatment

Base tubes (such as carbon steel, stainless steel, copper tubes, aluminum tubes) undergo derusting (sandblasting or pickling), degreasing cleaning to thoroughly remove surface oil and oxide layers, resulting in a clean surface with specific roughness. Fin raw materials (steel strips, aluminum strips, etc.) require flatness correction, annealing (to reduce hardness and increase plasticity), and surface cleaning.

2. Fin Forming and Bonding

This is the core. Through roll forming, welding, and other technologies, pretreated fin materials are bonded to the base tube at precise pitches and angles. The process requires precise control of temperature, pressure, tension, and speed to ensure uniform fin spacing (deviation ≤0.2mm) and tight.

3. Post-Processing and Enhancement

After bonding, hydraulic expansion is often performed, where high-pressure fluid (50-100MPa) radially expands the base tube to further tightly with the inner holes of the fins, achieving a of over 98%. For welded parts, annealing at 300-400°C may be added to eliminate processing stress and prevent deformation.

4. Surface Anticorrosion

Depending on the application scenario, finished products undergo treatments such as spraying environmentally friendly high-temperature resistant paint, galvanizing, phosphating, or passivation to enhance weather resistance and corrosion resistance.

5. Quality Inspection

Including appearance inspection (machine vision systems to identify fin cracks, deformation, and other defects), non-destructive testing (ultrasonic testing for gaps, requiring gap area to be less than 2% of total contact area), pressure testing (maintaining 1.5 times working pressure for 30 minutes to ensure no leakage), and performance testing (heat transfer efficiency on thermal test benches).

 

Material selection directly determines the performance and applicable scenarios of fin tubes:

- Base Tube: Pure copper tubes are optional for excellent thermal conductivity; aluminum tubes are optional for lightweight and cost considerations; carbon steel or seamless steel tubes are selected when needing to withstand high pressure and high temperature.

- Fin: Aluminum fins are lightweight and have good thermal conductivity, widely used in air conditioning and other industries; stainless steel fins are high-temperature and corrosion resistant, suitable for harsh environments such as chemical and power industries.

 

Currently, fin tube manufacturing processes are developing towards intelligence. By introducing AI visual inspection and automated production lines, product defect rates are controlled at extremely low levels (e.g., below 0.5%). Meanwhile, the application of new composite materials such as titanium alloys is also driving continuous progress in process technology, providing more solutions for efficient heat transfer.