For a flawless appearance
When cans and aluminium tubes leave the cold extrusion press they do not meet the requirements for lacquering and printing yet. Burr-free cutting brings them to the desired size, the trimmed wall length. Still, the aluminium looks rough and striated, but additional brushing of the cans removes the tiny bumps and creates a smooth surface - the best preparation for lacquering.
In a second step aluminium tubes get a thread for the screw cap or a profile for the subsequent positioning of a threaded nozzle. In addition, the tube shoulder can be brushed.