Flat file is used for: filing plane and outer surface;
Square file is used for: filing grooves and square holes;
Triangle file is used for: filing triangle groove, larger than 60. Inner corner surface;
Semicircular file is used for; File the inner curved surface and large round hole;
Round file is used for: filing round holes and small radius inner round holes.
(2) Plastic file (Shijin file). It is mainly used for fine machining and trimming the small parts on the workpiece that are difficult to machine. It consists of several files with various cross-section shapes.
(3) Special file. It is used for processing special surfaces of parts. It has two kinds: straight and curved, and its cross-section shapes are many.
