Definition
A sheet metal forming process in which a recess is pressed into thin aluminum alloy sheet at room temperature to allow a flush rivet head to sit level with the surface. Cold dimpling is generally limited to soft, ductile alloys and thinner gauges because harder or thicker materials may crack when dimpled without heat.
Plain English
Pressing a small cone-shaped dent into a piece of sheet metal — without heating it — so that a flush rivet can sit flat against the surface instead of sticking up.
Context Anchor
Seen in aircraft sheet-metal work, especially when preparing thin skin panels for flush rivets or flush screws.
Derivation
‘Dimple’ comes from Middle English, meaning a small natural hollow or depression (as in a cheek). ‘Cold’ here simply means the work is done at room temperature, in contrast to ‘hot dimpling,’ where the metal is heated to make it more workable.
Why Pilots Care
Pilots don’t perform this process, but understanding it helps when reviewing maintenance logs or repair work — flush rivets reduce drag, and proper dimpling is part of why a repaired skin panel is smooth and aerodynamically clean.
Analogy
It is like pressing a neat, planned hollow into thin metal so the top of a screw can sit level with the surface instead of sitting on top of it.
Intuition Check
Cold does not mean the part is chilled; it means the metal is formed without heating. Dimpling does not mean accidental denting; it means making a controlled recess for a fastener.
Example Sentence 1
The mechanic used cold dimpling on the thin aluminum skin so the flush rivets would sit level with the surface.
Example Sentence 2
Cold dimpling worked well on the thin fuselage panels without risking heat damage to the surrounding structure.