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NOCOLOK® flux brazing is ideally suited for the large scale joining of Al heat-exchangers
The flux and its residue are non-hygroscopic and in standard applications non-corrosive. NOCOLOK® flux is easily applied by flooding, spraying or dipping and the flux loading easily controlled. Brazed parts are ideally suited for painting or other surface treatments if enhanced corrosion resistance is desired. Complex product designs, continuous production, and a variety of alloy selections make the NOCOLOK® flux brazing process the preferred choice for the following industries:
Aluminium brazing is now the preferred process for the production of automotive heat exchangers such as radiators, condensers, evaporators and heater cores. Good corrosion resistance in standard applications, formability and high thermal conductivity make aluminium an ideal material for the construction of these heat exchangers.
Aluminium brazing involves joining of components with a brazing alloy, that is an aluminium alloy (Al-Si) whose melting point is appreciably lower than that of the components. This brazing alloy is usually placed adjacent to or in between the components to be joined and the assembly is then heated to a temperature where the brazing alloy melts but not the components. Upon cooling, the brazing alloy forms a metallurgical bond between the joining surfaces of the components.
In automotive heat exchanger applications, this filler metal is supplied via a thin sheet or clad on a core alloy. The core provides structural integrity while the low melting point Al-Si cladding alloy melts and flows during the brazing process, to provide upon cooling a metallic bond between the components.
Commercial & Residential Air Conditioning
Air-conditioning market has been evolving dramatically over the past decades. The most important factors on system design and alternative technologies are:
- Legislation and phase-out schedules for ozone depleting refrigerants
- Increased demand for comfort cooling
- Rising energy costs
- Regulations on energy efficiency
There are multiple ways to improve the efficiency of a given air-conditioning system. A minimization of the temperature difference between the airflows and the phase change temperatures of the refrigerants can be achieved by increasing the heat transfer surface area or by improving the heat transfer efficiency of the heat exchangers. Brazed microchannel heat exchangers have already proven that they are able to provide an elegant and cost effective solution for the utilization of this optimization potential – while also providing a number of other benefits.
Why brazed heat exchangers?
- Improved heat transfer performance
- Pressure drop reduction
- Refrigerant charge reduction
- Reliability in performance
- Recycling advantages
- Noise reduction
- Lower weight
Flame brazing aluminium to copper is common in the refrigeration industry where copper tubes are brazed to aluminium roll-bond panels or tubes. Brazing copper to aluminium is very similar to brazing aluminium to aluminium, but some precautions are necessary. In flame brazing the inter-diffusion of copper and aluminium can be halted rapidly by simply removing the heat source - in this case simply removing the flame is sufficient to allow the joint to cool quickly.
Household & Electrical Appliances
It is possible to braze aluminium and steel or stainless steel and this is practiced in the household appliance industry for the manufacturing of pots an pans for example.
In the manufacturing of pots and pans where there is a large surface area between the aluminium base plate and the pot, a mixture of filler metal powder and flux is often used. In aluminium tube to steel or stainless steel tube joining, conventional flame brazing techniques can be used. Filler metal wire, either pre-placed or fed into the joint must be used.