1. Application of filing

Use a file to cut the surface of the workpiece to make it reach the shape, size and surface roughness required by the part drawing. This processing method is called filing. The filing is simple and has a wide range of work. It is mostly used after cutting and sawing. , Filing can process planes, curved surfaces, inner and outer arcs, grooves and other complex surfaces on the workpiece. The highest precision of filing can reach IT7-IT8, and the surface roughness can reach Ra1.6-0.8μm. It can be used for forming prototypes, mold cavities and parts, and repairing workpieces during machine assembly. It is one of the main operating methods of fitter.

Second, the file

1. The material and structure of the file

Files are commonly made of carbon tool steel T10 and T12, and are hardened to HRC62～67 after heat treatment.

The file is composed of file surface, file edge, file tongue, file tail, wooden handle and other parts. The size of the file is expressed by the working length of the file surface. The teeth of the file are chopped out on the file cleaver.

2. Types of files

According to different purposes, files are divided into three categories: ordinary files (or fitter files), special files and plastic files (or mixed files). Among them, ordinary files are used the most.

Ordinary files are divided into five types according to the different cross-sectional shapes: flat files, square files, round files, semicircular files and triangular files; according to their lengths, they can be divided into seven types: 100, 200, 250, 300, 350 and 400mm; according to them The tooth pattern can be divided into: single tooth pattern, double tooth pattern (mostly used double tooth pattern); according to the tooth pattern and vegetable density, it can be divided into: coarse tooth, fine tooth and polished file, etc. (the thickness of the file is every 10mm long tooth The number of teeth on the surface is expressed by the number of teeth, the rough file is 4-12 teeth, the fine tooth is 13-24 teeth, and the polished file is 30-36 teeth).

3. Selection of files

Reasonable selection of files has a great impact on ensuring processing quality, improving work efficiency and prolonging the service life of files. The general principle of choosing a file is:

(1) Choose the shape and specification of the file according to the shape of the workpiece and the size of the processing surface:

(2) Choose the thickness of the file according to the requirements of the processing material's hardness, machining allowance, precision and surface roughness. Rough files have a large tooth pitch and are not easy to be blocked. They are suitable for rough machining (that is, large machining allowances, low precision grades and low surface quality requirements) and soft metals such as copper and aluminum; fine files are suitable for steel, cast iron and surface quality Filing of demanding workpieces; oil-shine files are only used to smooth the machined surface. The thinner the file, the smoother the surface of the filed workpiece, but the lower the productivity.