File is the main tool for filing, made of carbon tool steel. The main part of the file is the special file tooth pattern on the surface of the file. Keying is a machining method to cut the surface of workpiece to make its size, shape, position and surface roughness meet the requirements. File types are in the length range of 10 mm, and can be divided into coarse file, medium file, fine file and smooth file according to the number of teeth. The more teeth, the finer the teeth. Commonly used files can be divided into ordinary files and plastic files (assorted keys). Ordinary files are divided into flat files, square files, semi-circular files, triangular files and round files according to different cross-sectional shapes. Threaded keys are often used in automobile maintenance. Mainly used to repair damaged threads. The thickness of the key tool should be selected according to the nature of the processed material, the size of machining allowance, machining accuracy and surface roughness. Rough file is used to rough file or file nonferrous metals; Machining with intermediate gear after rough machining; Fine files are used to file workpieces with small machining allowance and low surface roughness, while smooth files are only used to polish the final surface of workpieces. In addition, according to the shape of the part to be machined, files with different sections are selected. Square file has teeth on all sides, which can file square holes or process right-angle workpieces. A semicircular file can be used to file concave surfaces. Circular file can be used to file arc-shaped workpieces or large circular holes. When choosing a file, the hardness of the file must be higher than that of the material before filing; Moreover, ordinary files cannot be used to file materials with low hardness such as copper and aluminum, because copper and aluminum will block the file teeth. Correct use of the file Before using the file, install a handle with the appropriate size of the file and check whether the handle is loose. Some documents, such as the new key of Shida tool, have their own handles. Four ways to save files. When using a large file, the grip method is as follows: hold the handle with your right hand, the end of the handle is placed in the palm of your thumb, the thumb is placed on the upper part of the handle, and the rest fingers hold the handle from top to bottom. The muscle at the root of the left thumb is pressed against the file, so that the thumb is naturally straightened, and the other four points are bent in the direction of the palm. Hold the front end of the file between the middle finger and the ring finger. When filing, the right forearm should be flush with the filing body and the right elbow should be raised. When using a medium-sized file, hold the file: the thumb and forefinger of the left hand gently hold the front end of the file, just like holding the key in the right hand. When using a small file, how to hold the file: the thumb of the right hand is placed on the top of the handle, the index finger is placed on the side of the handle, and the other finger holds the file handle from below; Press the index finger, middle finger and ring finger of the left hand in the middle of the key body to prevent the file body from bending. When using a plastic file, just hold it with your right hand, with your thumb on one side of the file handle, your index finger on it, and the rest of your fingers holding the file handle from top to bottom. In the process of filing, it is not allowed to rub the cutting surface, filings and files by hand, because the metal powder produced during key cutting is difficult to remove after sticking to the hand, which will lead to hand slip. The standing posture when filing is shown on the right. Hold the file with both hands and put it on the workpiece. The left arm is bent, and the forearm is basically parallel to the left and right direction in front of the workpiece file; The natural right arm is basically parallel to the front and back direction of the workpiece file. The distance from the tip of the right foot to the heel of the left foot is approximately equal to the length of the file. The left foot forms an angle of about 30 degrees with the center line of the rasping needle, and the right foot forms an angle of about 75 degrees with the center line of the rasping needle. Filing shall be carried out according to the following steps. At the beginning of filing, the body leans forward about 10, and the right foot extends backward to make full use of the effective length of the filing body. When the gear is pushed to 1/3 stroke, the body leans forward about 15, and the left leg slightly bends. When the right elbow is pushed forward to 2/3 stroke, the body gradually leans forward to about 18. When cutting the last 1/3 stroke, push the file to the end with your wrist, and your body will be natural. In addition, the following points should be noted when using documents: (1) Use one side of the new key first, and then use the other side of the dull key. In addition, we should make full use of the effective full length of the file in use, which can not only improve the filing efficiency, but also avoid the local wear of the file teeth. (2) Don't touch the water and oil on the key knife. When the groove teeth of the file are blocked by chain chips, they should be removed along the tooth line with a special copper wire brush. (3) Hardening the unbonded blank and crust of the workpiece. If there is hard skin on the surface of the casting or blank, it should be ground off with a grinding wheel or filed off with an old file before normal chain cutting. (4) The file cannot be used as a crowbar or a hammer. (5) The file is hard and brittle. Whether it is used or stored, it cannot be stacked with other tools or workpieces. In addition, it is also necessary to prevent files from falling to the ground to avoid damage. (6) The file must be cleaned after use and stored in a dry and ventilated place to avoid rusting. The introduction of the above small series on how to use files correctly ends here. I believe everyone knows more or less how to use files. I hope Bian Xiao's introduction can help everyone. Please give me a compliment if you like it.