Ultrasonic cleaning is performed in oscillating tanks made of stainless steel with aqueous cleaning liquids. The optimal effect of the ultrasound presupposes the application of suitable cleaning agents, ⇒ STAMMOPUR or TICKOPUR agents.
Some household cleaners such as commercially available dishwashing liquids are not suitable for ultrasonic cleaning, because they may contain chlorine ions. They destroy the passive protective layer of the stainless steel surface in the oscillating tank, and are therefore the cause of corrosion. Dark holes the size of pinholes arise, known as pitting /1, 2/.
Besides cleaners containing chlorine ions, rust sedimentation (known as extraneous rust), saline water, acidiferous contamination and acids on the stainless steel surface may be the cause of pitting. Extraneous rust arises from abnormal factors coming from outside, such as
• rust particles from the mains piping system or from a rusty part to be cleaned,
• metal parts, such as screws, metal filings, metallic powder and similar material remaining on the stainless steel surface.
How can pitting be avoided?
• Do not put any cleaning liquids containing chlorine ions in the stainless steel oscillating tank. STAMMOPUR and TICKOPUR cleaning agents from DR. H. STAMM GmbH,
Berlin, are free of chlorine ions and have been specially developed for ultrasonic cleaning. Observing the dosing and application instructions respectively, they guarantee thorough, rapid and gentle cleaning with ultrasound.
• Only use water of at least drinking water quality for preparing the cleaning liquid. Apply any water with salt content only in inset beakers.
• Clean parts with acidiferous contamination in inset beakers only.
• Do not use any acids or acidic cleaning fluids that are not permitted for ultrasonic cleaning.
• Remove any metal parts, filings and suchlike left lying in the oscillating tank. Eliminate small patches of rust immediately with a soft cloth and commercially available stainless
steel-cleaning products containing no abrasive additive. Do not use any steel wool, scraper or shaver for this.
/1/ Special Stainless Steel – Properties, Use, Edition 1989, published by the Special Stainless Steel Information Office, Düsseldorf.
/2/ Special Steel Cleaning Registered Association, Association of German Metallurgists.
“Non-rusting Steels”. Verlag Stahleisen mbH, Düsseldorf 1977.