The Importance of Surface Dust Test for Quality Assurance after Sandblasting

Sandblasting jobs remove fine layers of surface material from steel workpieces. Think about that for a moment, this is a subtractive operation. Not like shears or cutting blades, of course. Still, there’s no getting around the fact, metal is being removed, and it has to go somewhere. Abraded by a high-force, super-fine stream of scratchy sand, the surface dust formed here can be next to invisible.

What’s Surface Dust? 

In a hobbyist shop, a weekend warrior has got his hands on a fine sandblasting cabinet. The equipment is feature-rich, loaded with all the latest bells-and-whistles, as they say. Jobs are done in the garage while the DIY-er wears a respirator mask. Afterwards, he wipes away a thin film of steel dust. That’s perfectly fine for a home project, but it’s absolutely unacceptable in a commercial operation. First of all, compressed air pressure removes the film in fabrication shops, not a handyman’s brush. Secondly, the gear could be headed for one of the following installation sites:

• A kitchen or catering establishment
• A material-sensitive production environment
• A laboratory or hospital
• A residence or commercial property

Invisible to the naked eye or not, those coarse-edged grains can’t be left to their own devices.

Surface Dust Hazards 

Forming a surface contaminating film, the particles hamper the next stage of the post-production cycle. Protective coatings and polishing actions don’t work, topology optimizing processes seem destined to fail, and the workpiece is characterized as a troublemaker. The real troublemaker, though, is the microscopic film, the surface dust that’s interfering with the post-processing.

Released from the fabrication plant with steel and sand residue still adhering to the workpiece surface, the issue worsens. The iron filings could be slightly magnetic, so they’ll end up coating an electrical circuit. A short-circuit becomes inevitable. In food-safe applications, the dust is a contaminant. In air conditioning ducts, dust on sheet metal becomes a nasty respiratory irritant. Clean rooms, chemical processing facilities, even in labs and hospitals, the surface dust represents an unacceptable risk factor.

After the sandblasting operation and the pressurized jets of cleaning air have finished their work, the next order of business is the surface dust test. There to double-down on quality assurance guidelines, including the ISO 8502-3 regs, the test utilizes pressure sensitive adhesives tapes. Transparent to the eye, any remaining dust, be it metal or sand, can be viewed through a testing microscope. The inspection expert views dust density, type, and form. If the dust levels surpass acceptability levels, back the workpiece goes for another round of air blasting.

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