Process for combined chemical cleaning and etching of parts made of
aluminum and/or aluminum alloys including: (a) providing a cleaning and
etching solution including 5 30 grams/liter of phosphoric acid; 5 30
grams/liter of hydrogen fluoride; 120 220 grams/liter of sulfamic acid;
55 85.0 grams/liter of glycol ether; and balance water; (b) contacting
the parts with the solution for a time sufficient to achieve the desired
amount of cleaning and etching; (c) periodically measuring the etching
rate of the solution; (d) when the etching rate is below the required
minimum rate, adding sufficient hydrogen fluoride to restore the etching
rate above the required minimum rate; and (e) periodically adding
sufficient sulfamic acid to prevent the formation of scale made of
hydrated aluminum fluoride.