A form of adhesive wear in which sliding surfaces, often of similar metals, bond and rip apart, leaving raised lumps and plucked craters instead of a smooth wear scar. Stainless steel, aluminum and titanium threads and slides are notorious for it, and galling can seize parts within a few strokes. Anti-seize compounds, dissimilar material pairs, hard coatings and lower contact stress prevent it.
Stainless nut galled on the stud halfway down, next time put anti-seize on the threads first.
Slow down on stainless fasteners: fast power-tool assembly heats the threads and makes galling far more likely.
Also heard as
- cold welding
Related terms
Adhesive wear
Wear where touching asperities weld together and tear, moving metal from one surface to the other.
Pickup
Metal transferred from one sliding surface onto another, seen as smeared lumps after adhesive wear.
Scuffing
Sudden, severe adhesive damage where the oil film fails and sliding surfaces locally weld and tear.
Solid lubricant
Dry film material such as graphite, molybdenum disulfide or PTFE that cuts friction without a liquid.