Technical Resources
Can Washer Process By Andy Raynor, Stolle Why do we clean the cans? We must chemically clean aluminium formed products. The aluminium cleaning is to remove residual aluminium swarf, oil, smut, surface oxides and, most importantly, the near-surface disturbed layer as to provide a uniform surface to receive further treatment. The metal forming processes create the near-surface disturbed layer. This is due to the severe shear strain in the near-surface region from the interaction between the aluminium surface and the steel surfaces.
The disturbed layer nano-sized grains with grain boundaries decorated and pinned by oxide particles and lubricant residues. The removal of the near-surface disturbed layer is critical for the pre-treatment to be successful.
Where does the can washer sit in the line? The beverage can washer and dryer systems sits in the can making line between the Body Makers and the lacquer sprays and/or Basecoater. The washer has a number of tasks, the first is to clean the loose residues off the can following the metal forming processes. These residues include swarf and organic oils which are applied to keep the metal surfaces lubricated and cool during the intense mechanical pressures used to form the aluminum sheet into containers. The washer also prepares the aluminum
cans using acidic washing processes and rinsing to produce a bright shinny can that is dried prior to the cans being presented to the lacquer sprays/basecoater and decorating processes down stream. It is very important that the washer processes, both mechanical and chemical, are fully understood to ensure that the ever increasing production demands are satisfied. The washer system is a complex integration of mechanical spraying technology and chemical control to ensure the washer is as efficient as possible therefore reducing the cost of can manufacture.
FUNDAMETALS Newsletter
[ 10 ] Q1 2023
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