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Lines and machinery in the production of automotive air conditioning ducts (1)

Air conditioning in the car is associated with comfortable use of the vehicle, especially in summer. The guarantee of its proper functioning is not only regular servicing, but also the quality of workmanship of the various components of the system: compressor, evaporator, radiator and tubes. Air conditioning hoses should ensure the tightness of the refrigerant circuit and proper pressure and temperature resistance.

Briefly about refrigerants

Until 2017, R-134a refrigerant was very popular due to its good thermodynamic properties and high auto-ignition temperature (770°C). Unfortunately, it turned out that its GWP factor [1] is as high as 1430. This resulted in Directive 2006/40/EC, which banned the use of the refrigerant in newly manufactured vehicles from January 1, 2017. R134a was replaced by R1234yf with a GWP=4 and very similar cooling efficiency, unfortunately at the cost of a dangerously lower auto-ignition temperature (about 405°C). Alternative green compounds have also been selected for use in automotive air conditioning systems. The leading alternative here is paradoxically CO2 (R744), which ranks among the so-called natural refrigerants. It is non-toxic, non-flammable, colorless, inert and has no negative impact on the ozone layer. However, it places greater demands on the pressures and temperatures found in air conditioning components.

Production of air conditioning tubes

The various components of the air conditioning system are attached to various body or engine components. This exposes them to vibrations and mutual displacement, so sections of flexible ducting are used to connect them. The hoses can come in bundles of different numbers with the appropriate mounting flange. The cable consists of a rubber hose, metal ends (usually aluminum) and various types of connectors that allow their subsequent installation.

The metal end is formed from a tube so that it can be connected to the rubber hose. Mounting blocks are soldered to facilitate attachment and ensure tightness. An important stage of production is bending the aluminum tubing to the appropriate shape. It is determined by the vehicle model, type of engine, etc. Sometimes the tubes are equipped with heat exchangers to further accelerate the cooling of the air and thus reduce the load on the engine. After the metal tubes are formed, sealant is sprayed onto them. A vision system verifies the correct application of the sealant. The next step is to connect the metal parts to the rubber hose by means of clamping with metal bands.

The grade of rubber used should be characterized by its ability to dampen vibrations and ensure the tightness of the connection. The finished hoses undergo flow and leakage tests. Tightness is important due to high environmental standards, hence air is pumped out of a special chamber and helium is injected into the tubes. A spectrometer is used to detect leaks.

ELPLC air conditioning duct assembly and testing lines

Over the course of more than a dozen years, ELPLC has gained extensive experience in implementing stations and entire lines for manufacturers of automotive air conditioning components. They handle a range of processes found in the production of air conditioning ducts: induction brazing of aluminum components, chipless cutting of corrugated steel hose, TIG orbital welding with electrochemical passivation, band crimping, bundle completion or flow testing. In addition, lines built by ELPLC are equipped with ELPLC’s proprietary Smart Factory system. One of its functionalities is that the full production history of each piece is available and can be analyzed. This can be done with respect to various criteria and selected filters, such as efficiency analysis by station or operator. Data export is also available. Read more about ELPLC Smart Factory.


[1] GWP – Global Warming Potential – a coefficient of the potential to create a greenhouse effect, determined by comparing the amount of heat absorbed by a specific mass of gas to the amount of heat retained by a similar mass of carbon dioxide. GWP for CO2 is 1. The coefficient is recalculated for a specific time interval – usually 100 years

ELPLC SA machines and lines

We specialize in designing and building machines, complete robotic assembly lines and developing software for industry. We offer our expertise to many industries. We provide Industry 4.0 / Smart Factory solutions.

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