Metal finishing Q&As since 1989

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Removing laser scale for paint application

 

WHAT IS THE SIMPLEST WAY TO CLEAN LASER SCALE FROM STEEL PARTS? THESE PARTS GET PAINTED AND THE EDGES FLAKE OFF FROM THE LASER OXIDATION.

THANKS,

BRIAN PATTERSON
- St Paul, MN, USA

I don't know if this is the easiest or quickest way but at our shop we dip the parts into a tank of ambient temp 25% B.V. Hydrochloric acid. This removes the laser smut well but the parts have to be rinsed and dried well or flash rusting can occur soon after.

Lee Moss
- Calgary, Alberta, Canada
 

The two most common methods for removing laser smut are mechanically and chemically. You can use a grinding wheel or other abrasive to mechanically remove all traces of the laser smut. The other way is to use an acidic cleaner that will remove the oxide formed from the heat of the laser. If you are painting many parts, the chemical method will probably be easier to implement, since you may be able to clean many parts at the same time.

Dan Brewer
chemical process supplier - Gurnee, Illinois
 

Dear Brian:

The cleaning method very much depends on size, geometry and of course volume of parts, which you didn't pointed in your letter. As an example, small size rigid parts such as nuts, bolts, washers in high volume are mostly cleaned by vibratory machines or tumbled in chemical derusting solutions. Very large parts as plates, chassis, weldings, are most effectively cleaned by sand or shot blasting. Intermediate size parts can be degreased and pickled in acids.

Good luck.

Guillermo Marrufo
Monterrey, NL, Mexico
 

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I do not have direct experience with laser scale, and perhaps someone that does will post an answer for you. My suggestion is to see if hydrochloric acid will take it off. HCl generally does a good job removing oxides from steel, and is a very popular pretreatment step before coating or plating.

Tim Neveau
Rochester Hills, Michigan