4.3.2.1 Mechanical Cleaning by Hand

Mechanical cleaning by hand involves small-scale abrasion with a wire brush, sandpaper or other handheld abrasive media, all available in a range of roughnesses for everything from the removal of bulk material to polishing. Mechanical cleaning by hand requires no extra tools. The operator must control dimensional and roughness tolerances. As a rule of thumb, 120 to 180 grit sandpaper for metals and fine-to-medium abrasive fleece for plastics are recommended to prepare a surface for adhesive bonding.

4.3.2.2 Abrasion with Power Tools

Small handheld power tools or larger shop tools can speed the cleaning/roughening of surfaces. As in manual mechanical cleaning, a belt, rotary and orbital sanders may be used with abrasive media in a range of roughnesses; the operator must control the amount of material removed and, usually, one part is cleaned at a time.

Bristle blasting is abrasion using a rotary wire brush tool. The angle of the bristles and their acceleration as they are ‘snapped’ over a perpendicular bar give the bristle tips a speed and angle more like a particle-blasting treatment than a traditional rotary brush, leaving a pitted, clean surface.