A file (or hand-file) is a metalworking hand tool used to shape material by abrasion. A file typically takes the shape of a steel bar, most of which is covered with an array of crisscrossing steel ridges. One end of the bar, called the tang, is pointed and narrow and attaches to a round handle. Files should never be used without a handle, as the pointed tang can easily injure the operator.

Files come in a wide variety of sizes, shapes, and tooth sizes. File cross-sections can be flat, triangular, round, or half-round to suit the workpiece shape. Files can be very large and coarse (such as a rasp) or small and fine (such as a needle file).

Files have forward-facing cutting teeth, which means that the file only effectively cuts when pushed over the workpiece. Pulling a file over a workpiece or rapidly scraping a file back-and-forth is ineffective and will reduce the life of a file.

The grooves in a file may became clogged during use, causing the file to loose its cutting ability. A file card can be used to clean the file.

Diamond files

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Instead of having teeth cut into the file's working surface, diamond files (pictured to the right) have small particles of industrial diamonds embedded in their surface (or into a softer material that is bonded to the underlying surface of the file). The use of diamonds in this manner allows the file to be used effectively against extremely hard materials, materials that would blunt an ordinary high carbon steel file quickly.

Needle files

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The image to the left shows a selection of needle files in an assortment of cross sectional shapes.
A set usually consist of 12 files that are packaged in a soft pouch, both for ease of handling and protection of the files' teeth. They are small files that are used in applications where the surface finish takes priority over metal removal rates but they are most suited for smaller work pieces.
They are often used as pictured, however, like all files, they are safest when used with a handle. The handle is often designed around the collet principle which allows the files and handle to be interchanged quickly.

Riffler files

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Riffler files, as pictured to the right, are small to medium sized files in an assortment of cross sectional shapes and profiles. The varying profiles and shapes enable them to be used in hard to reach, or unusually shaped areas. They are often used as an intermediate step in die making where the surface finish of a cavity die may need to be improved. - eg; plastic injection moulding or die casting

Machine files

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The files pictured on the left are designed for use in a filing machine.

A filing machine is similar in appearance to a scroll saw or band saw in that the file is mounted vertically in the middle of a table. When in operation the file reciprocates vertically while the workpiece is presented to the file's face and manipulated around the table/file as the shape requires.

The cone point of the pictured, top two files allows the files to center themselves firmly in the bottom file holder. The pictured, lower two files are required to be inserted into the bottom file holder and physically restrained with set screws, an identical process as for the top holder.

Filing machines are useful tools as they reduce fatigue and improve product accuracy, and although not usually seen in modern production environments, they may be found in older toolrooms or diemaking shops as an aid in the manufacture of specialist tooling.

Metalworking hand tools

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