Files are divided into ordinary files, special files and plastic files (assorted files). Generally divided into square files, triangular files and so on. There are many shapes of special files. The size and diameter of plastic files are 4 mm, and the length is160 mm. Rough files are 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. The file cuts the surface of the workpiece to make the workpiece reach the required size, shape and surface roughness.

File tooth texture thickness grade:

No. 1 andNo. 1: used for coarse tooth files with pitch of 2.3 ~ 0.83mm. ..

2.2 grain: use a middle tooth file, and the tooth spacing is 0.77 ~ 0.42 mm. ..

3.3 grain: used for fine-tooth file, with the pitch of 0.33 ~ 0.25mm. ..

4.4 grain: used for double fine tooth files (sometimes called smooth file), and the tooth pitch is 0.25 ~ 0.2 mm. ..

No.5 and No.5 marks: used for smooth file, with the pitch of 0.2 ~ 0.16mm. ..