1. According to the shape of file section, ordinary files are divided into five types: flat file, square file, triangular file, semi-circular file and round file. Flat files are used to file curved surfaces, cylindrical surfaces and convex curved surfaces. Square files are used to file square holes, long square holes and narrow planes. Triangular files are used to file internal corners, triangular holes and planes. Semi-circular file is used to file concave surfaces and planes. Circular file is used to file round holes, concave cambered surfaces with smaller radius and elliptical surfaces.
2. Special files are used to file special surfaces of parts, including straight files and curved files.
3. Plastic files (assorted files) are suitable for trimming small parts of workpieces, and there are files with various cross-sectional shapes.