Filing is an important basic operation of fitter. The scope of filing is; that is, the outer surface of the workpiece can be filed, and the inner hole, groove, curved surface and various complicated surfaces can be filed. In addition, there are some inconvenient mechanical processing, but also need to file to complete. For example, in the process of collision and matching, the trimming and repairing of individual parts are all solved by filing. Therefore, filing is an important basic operation of fitter.
1. The structure of the file
The file material is made of carbon tool steel (T12A, T13A). After heat treatment, the hardness is HRC62～67. It is a standard tool produced by a professional factory.
The tooth pattern of the file has two kinds of single pattern and double pattern. The double pattern is a cross-arranged file pattern to form cutting teeth and empty chip grooves, which is convenient for chip breaking and chip removal. Single-grain files are generally used for filing thin and soft aluminum materials.
The working part of the file is divided into the knife surface and the knife edge. The edge of the knife refers to the two sides of the file. Some have no teeth, and some have teeth on one of the sides. The edge without filing teeth is called the smooth edge, which can make the adjacent face not hurt when filing the inner right-angled side.
2. File types
File shapes are flat, square, triangular, semicircular, and round. Files are long or short, large and small.
Files are divided into three categories: fitter files, special files, and plastic files. There are two commonly used files;
Flat file: File is suitable for filing flat and outer surfaces.
Square file: suitable for filing grooves and square holes.
Locksmith's file, triangle file: suitable for filing triangle grooves and angles greater than 60 degrees.
Half-circle file: suitable for filing inner curved surfaces, large round holes and planes that connect with arcs.
3. File specifications
File specification grade
File specifications are expressed in terms of the pitch of the teeth of the file. There are five types of tooth patterns.
Ⅰ Coarse tooth file: The pitch is 2.3～0.83mm. Use coarse-tooth files for machining allowances greater than 0.5 ~ 1.0mm.
Ⅱ Middle tooth file: Tooth pitch is 0.77～0.42mm. The machining allowance is 0.2 ~ 05.mm and the middle tooth file is selected.
Ⅲ Fine-tooth files: the pitch is 0.33～0.25mm. Fine-tooth files are selected for machining allowance of 0.1 ～ 02.mm.
Ⅳ Coarse oil file: Tooth pitch is 0.25～0.2mm. The machining allowance is 0.05 ~ 01.mm, and the rough oil polished file is used.
Ⅴ Fine polished file: Tooth pitch is 0.2～0.16mm. Use fine polished files for machining allowance between 0.02 and 0.05mm.
4. File method
The filing method refers to filing the surface. The filing surface is mainly flat filing and curved filing.
Flat filing is the most basic filing. Cross filing method: It is a filing method for roughing flat surfaces with a large margin.
Plane filing and smooth filing method: It is a filing method for small flat surfaces and finishing files.
Filing method Push filing method: It is a filing method for small planes, finishing and polishing.
Curved surface filing: Curved surface filing is based on the surface characteristics of the workpiece, and the movement of the file should be done
Curved filing can also be called rolling filing.
5. Filing operation requirements
Standing posture and position. Stand with two feet facing the vise, and the distance between the upper and lower arms of the vise is perpendicular to the upper and lower arms of the arm. The file is flat, the tip of the file can be placed on the workpiece, and then the left foot is taken. The distance from the right toe to the left heel is approximately equal to the length of the file , The left foot and the center line of the vise form an angle of about 30°, and the right foot and the center line of the vise form an angle of about 75 degrees. File posture. Flat file with both hands, left leg bent, right leg straight, body weight is on the left foot, both feet should always stand still, reciprocating movement by the flexion and extension of the left leg. Keep the file straight. When advancing the file, the pressure of both hands on the file should be kept stable and not swinging up and down. Have a goal when filing. Do not file blindly. In the process of filing, you must check the surface of the file with a measuring tool or a pallet frequently, so that the place to be filed must be cut with iron.
