What is a File -

File is one of the oldest and simplest, yet most useful hand tool for metal finishing, when it is applied with pressure against the surface of metal, it removes small bits of metal.

File is a hand cutting tool, designed with multiple teeth to remove stock by aberration and produce desired finish on different types of materials.

File is a “Very Useful” tool, however, it requires skill and practice to obtain good results.

Working principle of a File -
Any rough surface, if moved by using pressure along the surface of a work piece, will clean, polish, remove, erase or obliterate by friction, provided the rough surface is biting and harder than the work piece.