A vacuum coater, also referred to as a vacuum metallizer or barrier coating machine, consists of a vacuum chamber that has been evacuated to, typically, 0.0005 mbar.
Inside this chamber, aluminum wire is fed onto individual, resistance-heated inter-metallic evaporators, where the aluminum becomes molten and evaporates.
The flexible substrate, supported on a chilled process drum, passes over the evaporation source at speeds of up to 1000 m/min. The aluminum vapor condenses onto the substrate and so creates the coating layer.