There are many fine teeth and strips on the surface, which are hand tools for filing workpieces. It is used for micro-processing of metal, wood, leather and other surfaces.
The application of the file is very early, the oldest file that has been found is the bronze file of Egypt around 1500 BC.
Modern files are generally made of carbon steel by rolling, forging, annealing, grinding, chopping and quenching. The file is made of t12 steel, which has a hardness of 62~64 after surface quenching.
There are many types of files.
① According to the use, there are: ordinary fitter file, used for general filing; wood file, used for filing soft materials such as wood and leather; plastic file (assorted file), used for filing small and fine metal parts , There are many files of various cross-sectional shapes to form a set; files for sharpening woodworking saws; special files, such as flat and bow-shaped special-shaped files (special files), which are straight and curved.
②The files are divided into flat files (flat files), square files, semi-circular files, round files, triangular files, diamond-shaped files and knife-shaped files according to the cross-sectional shape (see picture). Flat files are used to file flat surfaces, outer circular surfaces and convex curved surfaces; square files are used to file square holes, long square holes and narrow surfaces; triangular files are used to file inner corners, triangular holes and flat surfaces; semicircular files are used to file concave curved surfaces and flat surfaces; round files are used to file round holes, concave arc surfaces and elliptical surfaces with smaller radii.
③The file is divided into two types: single-grain file and double-grain file according to the file pattern. The teeth of the single-grain file are inclined at an angle to the axis, which is suitable for processing soft non-ferrous metals; the main and auxiliary files of the double-grain file are arranged in a cross, which is used for processing steel and non-ferrous metals. It can divide wide filings into many small segments, making filing easier.
④The files are divided into Nos. Ⅰ～Ⅴ according to the number of main file lines in each 10mm length, of which No. Ⅰ is a coarse-toothed file, No. Ⅱ is a medium-toothed file, No. Ⅲ is a fine-toothed file, and No. Ⅳ and Ⅴ are glossy files. , respectively for roughing and finishing. The diamond file has no file pattern, but a layer of diamond powder is electroplated on the surface of the file to file hardened metal.