1. Flat file

Flat filing is the most basic filing, and there are three commonly used filing methods:

(1) Forward filing method
The file moves horizontally or vertically along the surface of the workpiece, and the filing plane can get straight file marks, which is more beautiful. It is suitable for filing, smoothing or filing of the workpiece.

(2) Cross filing method
The workpiece is filed sequentially in two intersecting directions. Since the file marks are crossed, it is easy to judge the unevenness of the filing surface, so it is also easy to file the surface. The cross filing method removes chips faster and is suitable for flat filing.

(3) Push file method
Hold the file symmetrically in both hands and push the file with both thumbs to file. This method is suitable for narrower surfaces that have been filed and have a small machining allowance to correct and reduce surface roughness.

2. Inspection of the quality of the filing plane

(1) Check the straightness and flatness of the plane
Use a steel ruler and a square ruler to check by the light transmission method, and check several parts and perform a diagonal check.

(2) Check the verticality
Use a square ruler to check by the light transmission method, and the reference plane should be selected, and then other surfaces should be checked.

(3) Check the size
Use steel ruler and vernier ruler to measure several times at different size positions according to dimensional accuracy.

(4) Check the surface roughness
Generally, it can be observed with the eyes, and the surface roughness sample can also be used for control inspection.