What Is a Knife File?

The file is made of carbon tool steel T12 or T13 after heat treatment, and then the working part is quenched. It is a small production tool. It is a hand tool for filing out workpieces. Used for micro processing of metal, wood, leather and other surface layers.

Many fine teeth and strips on the surface of the file

There are many types of files.

File body: The part between the file tip end and the file shoulder is the file body. For those without file shoulders

Selection of profile shape of file

The cross-sectional shape of the file should be selected according to the shape of the part being filed, so that the shapes of the two can be adapted. When filing the inner arc surface, choose a semi-circular file or a round file (small diameter workpiece); when filing the inner corner surface, choose

The characteristics of the file inspection hardness are: easy operation, easy to carry, not restricted by the size and shape of the workpiece, rapid detection, and good reliability. Therefore, in production practice, some workpieces whose appearance is not suitable for testing with a hardness tester, and workpieces with decarburized surfaces are often tested with a file.

The hardness test with a file in China began in the 1950s. Later, in the mechanical industry standard "General Rules for the Hardness Test of Steel Heat Treatment Parts", the file hardness test method was allowed to test steel quenched and tempered parts, carburizing, carbonitriding and carbon-nitrogen co-existence. Surface hardness of nitrided parts and nitrided parts. The inspection standard GB / T 13321-1991 "Steel Hardness File Inspection Method" was formulated and has been cancelled. Foreign countries such as the United States, Japan, Germany Garden, the former Soviet Union and other countries have also adopted this detection method within a certain range for many years. At the beginning of the 21st century, the United States, Japan and other countries have completed inspection standards and inspection specifications, and have a series of standard files. And standard test block supply.

File inspection hardness is suitable for quality inspection of various types of steels after heat treatment. Commonly used steels are structural steel, alloy structural steel, carbon and alloy tool steel, high-speed steel, mold steel, and carburized steel; heat treatment processes include ordinary quenching, high Frequency quenching, vacuum quenching, carburizing, carbonitriding, nitriding, etc. In addition, it is also suitable for the quality inspection of steel parts, especially in the mass production process, a certain percentage of products are often sampled and tested for hardness with a hardness tester, and the remaining products are 100% inspected with a file. ^[1]

1. There are burrs on the teeth of the new file. If you use Song file to cut hard metal, the burrs will be abraded and the file will be dulled at an early stage. Therefore, you cannot use a new file to harden the iron and steel.

2. The surface of oxidized or cast hard skin and unannealed hard steel parts can not be filed with new files. The oxidized scale and cast hard skin must be ground on the grinding wheel first. Only use it if it cannot be used. File off.

3. Do not use soft files to file soft metals (lead, tin, etc.), because the soft metal file layer is easily embedded in the tooth grooves of the file teeth, making the file slip on the surface of the workpiece.

4. Do not stack files together to avoid damage to the teeth.

5. Do not allow the file to get wet or put in a damp place to prevent rust.

6. When filing soft metal, the file teeth are often blocked by the file layer. At this time, the file layer can be brushed away with a wire file brush. In order to prevent the file teeth from being dulled by the wire brush, the wire brush should be brushed toward the hooked side of the wire in the direction of the file tooth. If the large filings are embedded, use a copper scraper to remove them, but remove them in the direction of the file teeth (ie, the direction of the arrow on the figure). ^[2]

To extend the life of the file, the following rules must be followed:

Do not use new files to defeat hard metals;

Do not use hard files to thwart hardened materials;

Forgings and castings with hard skin or sticky sand must be ground on a grinder before they can be filed with a semi-sharp file;

Use one side of the new file first, and then use the other side when the side is blunt;

When filing, always use a wire brush to remove chips on the file teeth;

Files must not overlap or be stacked with other tools;

Do not use the file too fast when using the file, otherwise it will be easy to wear prematurely;

The file should be protected from water, oil or other dirt;

Fine files are not allowed to file soft metals;

Use assorted files should not be too strong, so as not to break.