During the processing, the phenomenon of failures is normal, but it will be solved in time, but sometimes, some failures will not be found, so it is only discovered during the later use, so many users are choosing It is very important to learn how to inspect the product at that time. If you find a problem after buying it back, some merchants are not responsible for it. Then let’s take a look at the methods for inspecting precision machining. 1. Measuring method of outer diameter When measuring the outer diameter, it is necessary to measure and record at two locations in the circumferential direction. When the length of the part with the same diameter is greater than 50mm, it should be checked for straightness. The working surface of the knife edge ruler is in contact with the outer diameter bus bar, and the width of the building is observed, and then judged against the standard optical gap. 2. Measuring method of inner diameter When measuring the inner diameter of a part, just measure it at three locations in the circumferential direction and make a record at the same time. When the length of the same diameter is greater than 40mm, the cylindricity should be checked. Within the range of the length of the same diameter, two positions with a larger interval should be taken for measurement. Calculate the cylindricity error. 3. Measuring method of external thread The middle diameter of the external thread is measured with a threaded ring gauge or three needles, and the small diameter is measured with a threaded ring gauge (through gauge). 4. Measuring method of internal thread The outer diameter of the internal thread is inspected with a threaded plug gauge (through gauge), and the middle diameter is inspected with a threaded plug gauge. 5. Surface roughness detection The sample block comparison method is used for comparison and judgment. 6. Test of flatness Use the metering method to detect, place three adjustable supports on the plate, place the part on the support point with the measuring surface facing up, adjust the support points so that the three points are equal, and the peak and valley values ​​measured by the meter are flat Flatness error.