Files are divided into ordinary files, special files and plastic files (assorted files). Generally divided into square files, triangular files and so on. Special files with many shapes. You can check for yourself. The size, diameter and length of plastic file are 4 mm and 160 mm respectively, which are generally used for the correction of metal processing. File rough file is used for machining allowance of 0.5-1mm. The machining allowance of medium file is between 0.2 and 0.5. The machining allowance of the fine file is between 0.05 and 0.2, and the surface roughness can reach RA 1.6. When cutting the surface of a workpiece with a file, the workpiece can reach the required size, shape and surface roughness.

The thickness of the file depends on the size (pitch) of the teeth. The tooth thickness of the file is divided into the following categories:

1 pattern: used for coarse tooth files with a pitch of 2.3 ~ 0.83 mm. ..

No.2 grain: middle tooth file is used, and the tooth spacing is 0.77 ~ 0.42 mm

No.3 grain: used for fine-tooth file, with tooth pitch of 0.33 ~ 0.25mm. ..

No.4 grain: used for double fine-tooth files (sometimes called smooth files) with a pitch of 0.25 ~ 0.2 mm. ..

No.5 grain: used for smooth file, with the pitch of 0.2 ~ 0. 16mm.