What kind of quality defects do screws often encounter

What kind of quality defects do screws often encounter
In the process of pan head screws production, various quality defects are often caused by machine problems or employee negligence. Let's share the quality problems that screws often encounter.
1. The screw head is deformed and the head is skewed. The possible cause is improper installation of the first punch of the screw mold and improper adjustment of the machine.
2. The head of the screw is not round. The reason is the improper selection of the first die of the screw die or the insufficient filling of the first die.
3. The screws have burrs or burrs. The reason is that the first punch is poorly formed, which is mainly caused by the excessive gap between the punch rod and the die hole or the too short punch rod.
4. The screw head is cracked, and the screw head has cracks.
The reason for the damage of the compressor connecting rod screw and how to check it?
The main reasons for the damage of the compressor connecting rod screw, including breakage, elongation, and loose thread, are as follows:
1. The manufacturing quality of the screw is not good (including material processing, heat treatment, etc.);
2. When replacing the connecting rod screw or nut, it is not replaced as a set;
3. The screw cannot fit tightly with the screw hole at the big end of the connecting rod, and the gap is too large;
4. When tightening the connecting rod nut, please use too much force. Or on the same connecting rod, the torque of the two nuts is inconsistent;
5. The screw head and the nut are not evenly attached to the supporting surface of the connecting rod, and the screw is skewed after the nut is tightened;
6. The gap of the connecting rod bushing is too large or the ellipticity of the crank is too large. Normally, the connecting rod screw will not be damaged immediately, but due to the long-term existence of some of the above elements, it cannot be discovered in time. Caused by material fatigue. Therefore, in the maintenance process, the inspection of connecting rod screws and nuts should be strengthened, and attention should be paid to reasonable assembly to avoid accidents caused by damage to the connecting rod screws and nuts. Check whether the connecting rod screw is damaged. The following methods are usually used: 1. Use a magnifying glass five or ten times to carefully check the rounded corners of the screw and the vicinity of the screw for damage; 2. Use a magnetic powder flaw detector to check for cracks; 3. Check the tension of the gauge screw ; Check if the wire gauge is damaged.