About aluminium brazing
Le brasage est un métal se joindre à la méthode qui fournit un lien permanent entre les parties, s’est joint à l’aide d’un métal d’apport brasage.
La composition de l’alliage-liner est telle que son point de fusion est légèrement inférieure à l’intervalle de fusion de l’alliage de base.
Matériel de soudure va être rejoint principalement avec tôle (soit nu ou vêtu) ou tubes (extrudé ou soudés en aluminium laminé).
Brasage s’effectue à propos 600 degrés Celsius.
Le revêtement peut être sur une ou deux faces et comprend 2-17 % of the thickness on each side.
Brazed aluminium heat exchangers have been increasingly introduced to the automotive industry. Examples include automotive radiators, condensers, evaporators, heat cores, oil coolers, transmission oil coolers, air charge coolers, and fuel-cooling systems.
Advantages of aluminium brazing
- Easy to recycle
- Cheaper than copper
- High heat transfer performance
- Better durability
- Lighter than copper, which was used for engine cooling in the past
Aluminium brazing material production
Complex assemblies can be turned into single unit by just one pass through a brazing furnace. Aluminium brazing facilitates the joining of parts with a near-eutectic Al-Si filler alloy, the liquidus temperature which is about 50°C lower than that of the core. In serial heat exchanger production the filler alloy is supplied via a thin clad on a core alloy. Compound Material Aluminium brazing material is a sophisticated multi layer compound consisting of a core alloy which provides the strength and life cycle requirements of the heat exchanger and a clad brazing filler. A one-sided protection layer can also be clad, in order to prevent water-side radiator corrosion.
During brazing, only the clad brazing alloy melts, while the core alloys remain solid. The design and the applied materials of the heat exchanger are adjusted to optimize the brazing result regarding the required post braze mechanical properties as well as the corrosion resistance.
Roll cladding
Aujourd'hui, two basic cladding techniques, roll bonding and cast cladding, have become established industrially. Roll cladding is a solid-state welding process, which is used to join similar and dissimilar aluminium alloys, and represents the primary method of manufacturing fuselage skin, sheet for aircraft, bright products and brazing sheet for automotive applications. The cladding layers are attached to the core slab by welding and metallurgical bonding using hot rolling. The cast cladding technique is based on a conventional direct chill mould modified in order to allow multiple metal streams to be casted into one single aluminium ingot.
Cladding thickness
Roll bonding process guarantees tight cladding thickness tolerances, which are essential for ensuring stable brazing results. Extremely thin clad layers of 1.5% can be manufactured, as well as brazing materials with a cladding thickness of 20%.