Definition
A hand tool consisting of a hardened steel bar with rows of cutting teeth on its surface, used to shape, smooth, deburr, or remove small amounts of metal and other materials by abrasion. Files come in various shapes (flat, half-round, round, triangular, square), cuts (single-cut, double-cut), and coarseness grades (rough, coarse, bastard, second-cut, smooth, dead smooth).
Plain English
A metal tool with rough, ridged surfaces used to grind down or smooth metal by hand. You push it across the work and the small teeth shave off tiny bits of material.
Context Anchor
Seen in aircraft sheet metal, repair, and fitting work when a mechanic needs controlled material removal by hand.
Derivation
From the Old English 'feol,' meaning a tool with a roughened surface for smoothing. The word has carried the same basic meaning for over a thousand years.
Why Pilots Care
In aircraft maintenance, sharp edges and burrs left on metal parts can cause stress cracks, cut wiring or hands, and lead to part failure. A file is one of the primary tools used to remove these hazards and produce a safe, properly fitted component.
Intuition Check
Do not read file here as a computer document or as filing paperwork. In this maintenance context, a file is a cutting hand tool used on a physical part.
Example Sentence 1
After cutting the aluminum sheet to size, the technician used a flat file to remove the burrs along the edge.
Example Sentence 2
A fine-tooth file leaves a smoother finish when dressing rivet heads on the control surface.