PROCESS FOR REMOVING SOAP-CONTAMINATED CONVERSION LAYERS ON METAL WORKPIECES

摘要

In a process for removing soap-contaminated conversion layers on metal workpieces remaining after cold-forming, cleaning is effected with a cleaning agent containing dilute nitric, phosphoric and/or amidosulphonic acid at a temperature of above 60 ~C, the cleaning agent is cooled after sufficiently high load in the absence of the cleaned workpieces to a temperature below 55 ~C, the fatty acid layer floating up is separated and at least the greater portion of the aqueous phase is re-used for cleaning. Preferred embodiments of the invention include the re-use for cleaning of the aqueous phase by adjusting the active cleaning components to the nominal concentration, cleaning with a cleaning agent containing a tenside, especially alkyl amine ethoxlylate, and applying the process to the cleaning of soapy calcium aluminate coatings remaining on workpieces of aluminium or aluminium alloys after cold-forming.