Vacuum brazing machine VAB

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Overview
VAB vacuum brazing technology provides a fluxless solution for aluminum brazing by using magnesium as an alloy addition or as a solid charge. Magnesium evaporates in the vacuum to bind oxygen and water vapor, improving vacuum purity and reducing aluminum oxide on part surfaces. This enables rapid and uniform wetting of details. Vacuum aluminum brazing requires precise temperature control because the filler must liquefy before the base metal reaches solidus; the allowable temperature window is typically very small (~5–10 °C). VAB is suitable for complex geometries, internal and multi-surface joints, and a wide range of aluminum alloys and thicknesses.

Benefits

• Flux-free brazing removes the need for flux application and disposal
• Part pre-washing limited to pre-process cleaning
• Post-process parts are clean with a dull gray finish
• Eliminates corrosion spots associated with flux residues
• Environmentally friendly process atmosphere
• Repeatable joints due to uniform temperature and high vacuum
• No flux contamination or residue on components
• Consistent high-quality brazed assemblies

Processes

• Brazing (vacuum aluminum brazing, fluxless, magnesium-assisted)

Industries

• HVAC&R (heating, ventilation, air conditioning & refrigeration)
• Automotive
• Aerospace
• Railway
• Electronics and home appliances
• Power generation and power plant equipment manufacturers

Materials
All aluminum alloys that are suitable for flux brazing can be vacuum brazed. Some magnesium-containing alloys (for example in the 5xxx series) that are difficult to flux-braid can be processed by VAB. With proper technique, alloys from the 1xxx, 3xxx, 5xxx, 6xxx and 7xxx series can be vacuum brazed.

Product types / Options
VAB solutions are available in three main configurations:

• Batch VAB with suspended load and dedicated transport system
• Batch VAB for aerospace and commercial heat treatment, tray-loaded
• Multi-chamber VAB — continuous line

Additional/ancillary equipment in the VAB line:

• Vacuum deoiling furnace for removing oil from stamped parts before main brazing (pre-heat ~370–400 °C)
• Vacuum oil separator to accelerate deoiling and provide pre-heating before brazing
• Air cooling chamber with air exchangers for staged post-braze cooling: parts cooled below ~500 °C before transfer for final air cooling (after brazing at ~600 °C)

Environmental & energy-saving features

• Vacuum atmosphere eliminates need for harmful process gases and related emissions
• No CO2 emissions from brazing atmosphere; no fossil fuel combustion in process atmosphere
• Cooling gases (nitrogen, argon) can be recovered and returned to the system
• Reinforced thermal insulation reduces electrical consumption (≈20%)
• High-efficiency electrical components (IE3 motors, inverter control)
• Control systems and algorithms to limit pumping, heating and cooling energy use
• No harmful emissions; elimination of post-treatment washing linked to flux use

Technical specifications

• Process: Vacuum aluminum brazing (fluxless, magnesium-assisted)
• Flux substitute / activator: Magnesium (evaporates to bind oxygen and water vapor)
• Critical temperature control window (filler liquefaction to base metal solidus): approx. 5–10 °C
• Oil separator pre-heat: ~370–400 °C
• Main VAB heating range (examples): ~400 °C to ~600 °C (brazing around 600 °C)
• Post-braze cooling: cooled below ~500 °C before transfer to air cooling chamber
• Configurations: batch (suspended), batch (tray-loaded for aerospace/commercial HT), multi-chamber continuous line
• Auxiliary equipment: vacuum deoiling furnace, vacuum oil separator, air cooling chamber with exchangers
• Energy efficiency: reinforced insulation, IE3 motors, inverter controls, energy-limiting algorithms
• Suitable alloys: series 1xxx, 3xxx, 5xxx (including some Mg-containing), 6xxx, 7xxx