Hollow Copper Tube Manufacturers

What are the common manufacturing processes of hollow copper tube?

In modern manufacturing, Hollow Copper Tube is widely used in many fields such as air conditioning and refrigeration, heat exchangers, automotive parts, machinery manufacturing, electronic appliances, chemical equipment, etc. due to its excellent thermal conductivity, corrosion resistance and good processing performance. With the continuous improvement of downstream industries' requirements for copper tube precision, performance and environmental protection, the manufacturing process of copper tube is also constantly evolving and upgrading.
Since its establishment in 1994, Zhejiang Jingliang Copper-Tube Products Co., Ltd. has focused on the research and development and manufacturing of copper tubes, and has now formed a complete industrial chain covering smelting, extrusion, drawing, annealing, and precision rolling.
Analysis of key processes in copper tube manufacturing
1. Copper billet smelting (Melting & Casting)
The manufacture of hollow copper tubes begins with the selection and smelting of raw materials. High-purity cathode copper is heated to above 1200°C in Jingliang's efficient smelting workshop, and is cast into defect-free round copper billets after deoxidation, refining and other processes. This stage plays a decisive role in the metallographic structure and physical properties of the finished product.
2. Hot Extrusion
After the copper billet is heated and softened, it is hot extruded by a hydraulic extruder. This process is the key to achieving the hollow tube structure: the metal is pushed in a closed mold and extruded through a mold with a mandrel to form a hollow structure.
Zhejiang Jingliang has advanced automated extrusion equipment, which can produce hollow copper tubes of various specifications (round, square, special-shaped) according to different customer needs, and achieve precise control of inner and outer diameter dimensions and wall thickness distribution.
3. Cold Drawing
The copper tube after hot extrusion usually has a rough surface and large dimensional deviation. At this time, one or more cold drawing processes are required to further improve the dimensional accuracy and surface quality. Cold drawing can not only improve the grain arrangement direction and increase the strength of the tube, but also create conditions for subsequent annealing treatment.
Jingliang uses multi-channel drawing equipment in the cold processing stage, combined with self-developed lubrication and tension control systems to ensure the consistency and stability of each meter of copper tube, which is a key link for the product to meet high-end applications (such as heat exchangers and automotive refrigeration systems).
4. Intermediate Annealing
After multiple cold drawing, the copper material will gradually harden and become more brittle. At this time, it is necessary to restore its plasticity through intermediate annealing. The annealing temperature is usually controlled at 400~700°C, and the time and atmosphere need to be precisely controlled to avoid grain coarsening or oxide scale formation.
Jingliang is equipped with a high-precision controlled continuous annealing furnace, which can achieve efficient online annealing and provide sufficient machinability for subsequent deep processing such as bending and flaring.
5. Precision Rolling & Sizing
Some products that have extremely high requirements for size and wall thickness consistency (such as copper capillaries or high-precision copper tubes for refrigeration) also require precision rolling. This process uses multi-roll staggered rolling to effectively control wall thickness deviation, improve roundness, and eliminate residual stress.
6. Surface treatment and non-destructive testing
In order to improve the oxidation resistance and appearance quality of copper tubes, some products need to be phosphated, coated or brightened. At the same time, in order to ensure that there are no pores, inclusions or cracks inside the product, Jingliang fully introduces eddy current testing, ultrasonic testing and water pressure testing before leaving the factory to ensure that the quality of each hollow copper tube is up to standard.

Why hollow copper tubes are better than aluminum tubes in refrigeration systems

In today's rapid development of refrigeration systems, the choice of pipeline materials is directly related to the energy efficiency, life and reliability of equipment. Copper tubes and aluminum tubes, as two commonly used materials, have long been widely discussed in the industry. In actual applications, hollow copper tubes have shown comprehensive advantages over aluminum tubes in many key dimensions such as heat transfer performance, mechanical strength, corrosion resistance and maintenance convenience. As a professional manufacturer with more than 30 years of experience in the copper tube industry, Zhejiang Jingliang Copper-Tube Products Co., Ltd. has relied on advanced technology and a complete industrial chain to continuously provide high-quality hollow copper tubes to global customers, safeguarding the operation of refrigeration systems.
Excellent thermal conductivity, improving system energy efficiency
The thermal conductivity of copper is about 398 W/m·K, much higher than that of aluminum, which is about 237 W/m·K. This means that under the same working conditions, copper tubes can complete heat exchange more efficiently, thereby speeding up the refrigeration process and improving the energy efficiency ratio (COP) and energy-saving performance of the whole machine. This is especially critical in equipment such as air conditioners, refrigerators, and chillers that have increasingly stringent requirements for energy efficiency.
The hollow copper tubes produced by Zhejiang Jingliang are processed through precision extrusion and cold drawing processes to ensure uniform wall thickness and smooth inner wall, greatly improving the refrigerant flow rate and heat exchange efficiency, and are widely used in various high-end condensers and evaporators.
Excellent mechanical strength to ensure stable operation of the system
Compared with aluminum tubes, copper tubes have higher tensile strength and ductility, and are not easy to deform or break when subjected to high system pressure and thermal expansion and contraction. Under high-load conditions such as variable frequency compressors and heat pump systems, copper tubes can work stably for a long time, significantly reducing the failure rate.
Zhejiang Jingliang relies on a complete production system to fully control every quality checkpoint from copper ingot smelting, extrusion, drawing, annealing to finished product inspection. The hollow copper tubes produced can meet the working pressure of up to 70 bar and fully meet the current application requirements of new high-pressure refrigerants such as R410A and R32.
Excellent corrosion resistance to extend the service life of equipment
Copper will naturally form a dense oxide film in the air, which has extremely strong corrosion resistance, especially in humid, high-salt or acidic environments. Aluminum tubes are more prone to pitting, perforation and other problems, especially in the outdoor unit of the air conditioner where condensed water is attached for a long time.
In order to further improve the corrosion resistance of copper tubes, Zhejiang Jingliang can provide a variety of deep processing services such as surface phosphating, degreasing, cleaning annealing, etc., which effectively extend the service life of the product and reduce the frequency of later replacement and maintenance costs.
Installation convenience and maintenance advantages
The flexibility and welding performance of copper tubes make them more advantageous in installation and maintenance. Copper tubes can be bent with a small radius without breaking, which is suitable for internal machine layout with limited space; at the same time, copper can be easily connected through silver soldering or brazing processes to form joints with excellent sealing, which is far better than aluminum tubes that require special ferrules or welding auxiliary parts.
In the later maintenance of equipment, once the copper tube leaks or is damaged, it can be repaired or replaced on site, greatly improving the efficiency of after-sales processing. Zhejiang Jingliang provides customers with personalized customization including fixed-length cutting, port expansion, and precision straightening to further optimize installation convenience.

How to avoid collapse or deformation of hollow copper tubes during processing

Scientifically designing wall thickness and structural parameters is the first line of defense to prevent collapse
Whether the hollow copper tube is easy to collapse depends on the ratio of its wall thickness to diameter (D/t). When the ratio is too large, that is, the tube wall is too thin or the diameter is too large, a slight lateral force may cause structural instability. In the product design stage, Zhejiang Jingliang uses finite element analysis (FEA) to simulate the stress of the tube structure and reasonably plan the wall thickness parameters in combination with customer applications and pressure levels.
In the Φ6.35mm and Φ9.52mm capillaries widely used in the air-conditioning and refrigeration industry, Zhejiang Jingliang strictly controls the wall thickness to be above 0.5mm, and ensures the uniformity of the wall thickness through precise extrusion die design and high-precision rolling equipment, so as to avoid the "hose effect" or local bulging in subsequent processing to the greatest extent.
Adopting multi-pass progressive cold drawing technology to improve the strength of the tube
Drawing is the key process for copper tubes to become thinner from thick, and it is also the link that is most likely to deform. Zhejiang Jingliang introduced a continuous cold drawing line and a hydraulic tension control system, and implemented a multi-pass, low deformation rate cold processing strategy to avoid weak points in the tube body caused by excessive one-time stretching.
During the cold drawing process, the surface of the copper tube is lubricated with precision oil, and protective gas or inert medium is introduced into the inside for support to form a balanced force field of "inner support and outer lead", which effectively suppresses the axial buckling and lateral collapse of the hollow structure during deformation.
Precisely control the annealing temperature to ensure structural rebound and flexibility
Annealing is used to eliminate the work hardening of the copper tube and improve its plasticity and bendability. However, if the annealing temperature is not properly controlled, it is easy to make the metal grains coarse, causing the copper tube to collapse or flatten laterally during bending or spinning.
Zhejiang Jingliang uses a fully automatic continuous bright annealing furnace to heat treat the copper tube in an oxygen-free environment. The annealing temperature is precisely controlled at 600°C±5°C to ensure that the tube body restores flexibility while maintaining sufficient structural strength to meet the high-precision process requirements of U-bends, coils, fin tubes, etc.
High-precision mold system to ensure symmetry and support stability during processing
The design and precision of the mold play a decisive role in whether the hollow copper tube collapses asymmetrically. Zhejiang Jingliang independently developed and optimized a set of high-precision mold management systems for a long time. Each set of molds is processed by imported mold steel CNC, with the precision error controlled within 0.005mm. Different inner core structures are matched according to product models and uses to effectively support the inner wall of the hollow tube.
During the stretching or expansion process, the mold core is always centered, and the degree of wear is regularly checked to ensure that the hollow copper tube is always in an axially symmetrical force field during each processing to avoid deformation caused by eccentricity of the tube body.