knurls
Textured metal bumps
Knurls are small ridges or beads forming a textured pattern, typically on metal surfaces.
The knurling on a tool handle or bottle cap provides grip, preventing slippage: The knurls on the flashlight made it easy to hold with wet hands.
To knurl is to create this pattern, usually by pressing a toothed wheel against rotating metal on a lathe.
ridged
Having raised lines
textured · crosshatched · grooved · dimpled · embossed · coarse · patterned · raised · serrated · diamond-shaped
lathe
Rotating shaping machine
grooving · crosshatch · mill · precision · threading · spindle · roller · tolerance · handle · press-fit
surface texture
knurlssmooth surface
Plane without irregularities
smooths · polished · polishes · sleek · smooth surfaces